[PATCH] checkout: add --autostash option for branch switching

[PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches, local modifications in the working tree can
prevent the checkout from succeeding.  While "git rebase" and "git
merge" already support --autostash to handle this case automatically,
"git checkout" and "git switch" require users to manually stash and
unstash their changes.

Teach "git checkout" and "git switch" to accept --autostash and
--no-autostash options that automatically create a temporary stash
entry before the branch switch begins and apply it after the switch
completes.  If the stash application results in conflicts, the stash
entry is saved to the stash list so the user can resolve them later.

Also add a checkout.autoStash configuration option that enables this
behavior by default, which can be overridden with --no-autostash on
the command line.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: 'autostash' for branch switching

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v1
Pull-Request: https://github.com/git/git/pull/2234

 Documentation/config/checkout.adoc |  12 ++
 Documentation/git-checkout.adoc    |   9 ++
 Documentation/git-switch.adoc      |   9 ++
 builtin/checkout.c                 |  16 +++
 t/meson.build                      |   1 +
 t/t2061-switch-autostash.sh        | 181 +++++++++++++++++++++++++++++
 t/t9902-completion.sh              |   1 +
 7 files changed, 229 insertions(+)
 create mode 100755 t/t2061-switch-autostash.sh

diff --git a/Documentation/config/checkout.adoc b/Documentation/config/checkout.adoc
index e35d212969..2e157c5398 100644
--- a/Documentation/config/checkout.adoc
+++ b/Documentation/config/checkout.adoc
@@ -36,6 +36,18 @@ with a small number of cores, the default sequential checkout often performs
 better. The size and compression level of a repository might also influence how
 well the parallel version performs.
 
+`checkout.autoStash`::
+	When set to true, automatically create a temporary stash entry
+	before the operation begins, and apply it after the operation
+	ends.  This means that you can run `git checkout` or `git switch`
+	on a dirty worktree.  However, use with care: the final stash
+	application after a successful branch switch might result in
+	non-trivial conflicts.
+	This option can be overridden by the `--no-autostash` and
+	`--autostash` options of linkgit:git-checkout[1] and
+	linkgit:git-switch[1].
+	Defaults to false.
+
 `checkout.thresholdForParallelism`::
 	When running parallel checkout with a small number of files, the cost
 	of subprocess spawning and inter-process communication might outweigh
diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..96d9bf9203 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -272,6 +272,15 @@ When switching branches with `--merge`, staged changes may be lost.
 	`merge.conflictStyle` configuration variable.  Possible values are
 	`merge` (default), `diff3`, and `zdiff3`.
 
+`--autostash`::
+`--no-autostash`::
+	When switching branches, automatically create a temporary stash
+	entry before the operation begins, and apply it after the
+	operation ends.  This means that you can switch branches on a
+	dirty worktree.  However, use with care: the final stash
+	application after a successful branch switch might result in
+	non-trivial conflicts.
+
 `-p`::
 `--patch`::
 	Interactively select hunks in the difference between the
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..b296df2a0b 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -142,6 +142,15 @@ should result in deletion of the path).
 	`merge.conflictStyle` configuration variable.  Possible values are
 	`merge` (default), `diff3`, and `zdiff3`.
 
+`--autostash`::
+`--no-autostash`::
+	Automatically create a temporary stash entry before the
+	operation begins, and apply it after the operation ends.
+	This means that you can switch branches on a dirty worktree.
+	However, use with care: the final stash application after a
+	successful branch switch might result in non-trivial
+	conflicts.
+
 `-q`::
 `--quiet`::
 	Quiet, suppress feedback messages.
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 1d1667fa4c..453dbe3230 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,6 +30,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -68,6 +69,7 @@ struct checkout_opts {
 	int only_merge_on_switching_branches;
 	int can_switch_when_in_progress;
 	int orphan_from_empty_tree;
+	int autostash;
 	int empty_pathspec_ok;
 	int checkout_index;
 	int checkout_worktree;
@@ -1202,9 +1204,16 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (opts->autostash) {
+		if (repo_read_index(the_repository) < 0)
+			die(_("index file corrupt"));
+		create_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 		if (ret) {
+			apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
 			branch_info_release(&old_branch_info);
 			return ret;
 		}
@@ -1215,6 +1224,8 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
 
@@ -1236,6 +1247,10 @@ static int git_checkout_config(const char *var, const char *value,
 		opts->dwim_new_local_branch = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "checkout.autostash")) {
+		opts->autostash = git_config_bool(var, value);
+		return 0;
+	}
 
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
@@ -1745,6 +1760,7 @@ static struct option *add_common_switch_branch_options(
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
 			 N_("do not check if another worktree is using this branch")),
+		OPT_AUTOSTASH(&opts->autostash),
 		OPT_END()
 	};
 	struct option *newopts = parse_options_concat(prevopts, options);
diff --git a/t/meson.build b/t/meson.build
index f66a73f8a0..0645253d25 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -275,6 +275,7 @@ integration_tests = [
   't2030-unresolve-info.sh',
   't2050-git-dir-relative.sh',
   't2060-switch.sh',
+  't2061-switch-autostash.sh',
   't2070-restore.sh',
   't2071-restore-patch.sh',
   't2072-restore-pathspec-file.sh',
diff --git a/t/t2061-switch-autostash.sh b/t/t2061-switch-autostash.sh
new file mode 100755
index 0000000000..6409a2afbf
--- /dev/null
+++ b/t/t2061-switch-autostash.sh
@@ -0,0 +1,181 @@
+#!/bin/sh
+
+test_description='checkout/switch --autostash tests'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	echo file0content >file0 &&
+	echo file1content >file1 &&
+	git add . &&
+	test_tick &&
+	git commit -m "initial commit" &&
+	git branch other-branch &&
+	echo file1main >file1 &&
+	git add . &&
+	test_tick &&
+	git commit -m "modify file1 on main" &&
+	git checkout other-branch &&
+	echo file1other >file1 &&
+	git add . &&
+	test_tick &&
+	git commit -m "modify file1 on other-branch" &&
+	echo file2content >file2 &&
+	git add . &&
+	test_tick &&
+	git commit -m "add file2 on other-branch" &&
+	git checkout main
+'
+
+test_expect_success 'switch --autostash on dirty worktree' '
+	git branch branch1 other-branch &&
+	echo dirty >file0 &&
+	git switch --autostash branch1 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'checkout --autostash on dirty worktree' '
+	git branch branch2 other-branch &&
+	echo dirty >file0 &&
+	git checkout --autostash branch2 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git checkout main
+'
+
+test_expect_success 'switch: checkout.autostash config' '
+	git branch branch3 other-branch &&
+	echo dirty >file0 &&
+	test_config checkout.autostash true &&
+	git switch branch3 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'checkout: checkout.autostash config' '
+	git branch branch4 other-branch &&
+	echo dirty >file0 &&
+	test_config checkout.autostash true &&
+	git checkout branch4 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git checkout main
+'
+
+test_expect_success '--no-autostash overrides checkout.autostash' '
+	git branch branch5 other-branch &&
+	echo dirty >file1 &&
+	test_config checkout.autostash true &&
+	test_must_fail git switch --no-autostash branch5 2>stderr &&
+	test_grep ! "Created autostash" stderr &&
+	git checkout -- file1
+'
+
+test_expect_success '--autostash overrides checkout.autostash=false' '
+	git branch branch6 other-branch &&
+	echo dirty >file0 &&
+	test_config checkout.autostash false &&
+	git switch --autostash branch6 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'autostash with dirty index' '
+	git branch branch7 other-branch &&
+	echo dirty-index >file0 &&
+	git add file0 &&
+	git switch --autostash branch7 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty-index >expected &&
+	test_cmp expected file0 &&
+	git checkout -- file0 &&
+	git switch main
+'
+
+test_expect_success 'autostash bypasses conflicting local changes' '
+	git branch branch8 other-branch &&
+	echo dirty >file1 &&
+	test_must_fail git switch branch8 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git switch --autostash branch8 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard &&
+	git switch main
+'
+
+test_expect_success 'autostash is a no-op with clean worktree' '
+	git branch branch9 other-branch &&
+	git switch --autostash branch9 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git switch main
+'
+
+test_expect_success '--autostash with --merge stashes and switches' '
+	git branch branch10 other-branch &&
+	echo dirty >file0 &&
+	git switch --autostash --merge branch10 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'autostash with staged conflicting changes' '
+	git branch branch11 other-branch &&
+	echo staged-change >file1 &&
+	git add file1 &&
+	git switch --autostash branch11 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard &&
+	git switch main
+'
+
+test_expect_success '--autostash with --force preserves dirty changes' '
+	git branch branch12 other-branch &&
+	echo dirty-force >file1 &&
+	git switch --autostash --force branch12 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard &&
+	git switch main
+'
+
+test_expect_success '--autostash with new branch creation' '
+	echo dirty >file0 &&
+	git switch --autostash -c branch13 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main &&
+	git branch -D branch13
+'
+
+test_done
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 2f9a597ec7..f33ca543a9 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -2602,6 +2602,7 @@ test_expect_success 'double dash "git checkout"' '
 	--ignore-other-worktrees Z
 	--recurse-submodules Z
 	--auto-advance Z
+	--autostash Z
 	--progress Z
 	--guess Z
 	--no-guess Z

base-commit: 7f19e4e1b6a3ad259e2ed66033e01e03b8b74c5e
-- 
gitgitgadget

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> When switching branches, local modifications in the working tree can
> prevent the checkout from succeeding.  While "git rebase" and "git
> merge" already support --autostash to handle this case automatically,
> "git checkout" and "git switch" require users to manually stash and
> unstash their changes.
>
> Teach "git checkout" and "git switch" to accept --autostash and
> --no-autostash options that automatically create a temporary stash
> entry before the branch switch begins and apply it after the switch
> completes.  If the stash application results in conflicts, the stash
> entry is saved to the stash list so the user can resolve them later.
>
> Also add a checkout.autoStash configuration option that enables this
> behavior by default, which can be overridden with --no-autostash on
> the command line.

Unconditionally always stash when checkout happens?  This feature as
implemented does not have to be a separate feature.  It can be done
by end-users as a short-cut for "stash" followed by "checkout" via
alias or custom command.

Perhaps doing it this way would make it more worth doing?

 - At the beginning of branch switching, ask a new helper function
   that takes the branch we are switching to as an argument this
   question:

   Do any paths that are different between the current branch and
   the branch we are switching to have local (i.e., either in the
   index or in the working tree) change [Yes/No]?

 - When the answer is "yes", save the local changes to a new stash
   entry, and clear the local changes from the index and from the
   working tree.  If not, do not bother with stash at all.

 - Switch to other branch the usual way.  This will never conflict.

 - If we created a stash entry earlier, try to unstash it.  It may
   conflict or it may not.  

   - If it does not conflict, then we are done.  We drop that stash
     entry, and tell nothing about the stash to the user, as there
     is nothing they can do to the now-consumed stash.

   - If it does conflict, tell the user that the original change is
     in the stash, and can be used to recover if you botch the
     conflict resolution, and also tell the user that they need to
     drop the stash entry once they are done with the change that
     caused this current conflict.

Essentially, the new "autostaash only when needed" would become a
much better reimplementation of the "-m" option.  From the point of
view of a user who is used to "checkout -m", the basic workflow
would be the same, only with vast improvement.

 - It may not conflict and merge cleanly, in which case they do not
   have to do anything.  This is the same as status quo.

 - It may conflict and they find it too involved to resolve right at
   the moment, in which case they now have a choiceto say "git reset
   --hard", essentially declaring "I prioritize working on this new
   branch; I'll deal with the work in progress I started on the
   previous branch later", and then later they can "git stash pop"
   to deal with it.

   Which is a vast improvement over the current "-m" that gives you
   only one chance to resolve it right.

 - It may conflict and they may be able to resolve cleanly, in which
   case they have to remember that they need to do an extra thing
   (i.e., drop the stash we created just in case) but that may not
   be too bad a tradeoff.

If we can sell it as an improved implementation of "-m", we probably
can lose some code that the current "-m" implementation uses to do
its merge; we'd be instead using the "unstash" code paths.

And the new helper function to detect if switching from one commit
to another commit would never conflict can later be used to enhance
"git rebase" as well---we could call it N times to rebase a branch
with N commits and if all steps are clear, we do not have to insist
that there is no local changes like we do currently.

Hmm?

Re: [PATCH v31 0/2] status: add status.compareBranches config for multiple branch comparisons

[Harald Nordgren]

Good point! I have been running this today, and it gets a bit annoying when
it's stashing and unstashing needlessly.

I updated the code!


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Phillip Wood]

On 12/03/2026 14:40, Junio C Hamano wrote:
> 
> Perhaps doing it this way would make it more worth doing?
> 
>   - At the beginning of branch switching, ask a new helper function
>     that takes the branch we are switching to as an argument this
>     question:
> 
>     Do any paths that are different between the current branch and
>     the branch we are switching to have local (i.e., either in the
>     index or in the working tree) change [Yes/No]?
> 
>   - When the answer is "yes", save the local changes to a new stash
>     entry, and clear the local changes from the index and from the
>     working tree.  If not, do not bother with stash at all.

Can we avoid the extra check and stash if the user passed "--autostash" 
and unpack_trees() fails because it would overwrite local changes in 
merge_working_tree()?

> If we can sell it as an improved implementation of "-m", we probably
> can lose some code that the current "-m" implementation uses to do
> its merge; we'd be instead using the "unstash" code paths.

That would be nice but I think "git checkout --recurse-submodules -m 
<branch>" currently updates submodules whereas "git stash" does not know 
how to recurse submodules.

It would be nice to teach "git stash" to recurse submodules but I don't 
think it is completly straight forward as we'd need to store the object 
id of the submodule's stash commit in the parent stash.

Thanks

Phillip

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Phillip Wood <phillip.wood123@gmail.com> writes:

> On 12/03/2026 14:40, Junio C Hamano wrote:
>> 
>> Perhaps doing it this way would make it more worth doing?
>> 
>>   - At the beginning of branch switching, ask a new helper function
>>     that takes the branch we are switching to as an argument this
>>     question:
>> 
>>     Do any paths that are different between the current branch and
>>     the branch we are switching to have local (i.e., either in the
>>     index or in the working tree) change [Yes/No]?
>> 
>>   - When the answer is "yes", save the local changes to a new stash
>>     entry, and clear the local changes from the index and from the
>>     working tree.  If not, do not bother with stash at all.
>
> Can we avoid the extra check and stash if the user passed "--autostash" 
> and unpack_trees() fails because it would overwrite local changes in 
> merge_working_tree()?

Sorry, but I couldn't quite figure out what you are saying here.

My guess on one part of what it says is that an explicit
"--autostash", we should stash without second guessing the user
(i.e., avoid chedk and stash).  But then the latter part of the
sentence "and unpack_trees() fails ..." do not quite parse.

If the user gave "--autostash" and we check with unpack_trees()
dry-run and find out that a normal branch switch will be interfered
by the local changes, then we would stash, but that check made by a
dry-run unpack_trees() is not an "extra" check, so, that does not
work as a guess of what you are saying, either.

>> If we can sell it as an improved implementation of "-m", we probably
>> can lose some code that the current "-m" implementation uses to do
>> its merge; we'd be instead using the "unstash" code paths.
>
> That would be nice but I think "git checkout --recurse-submodules -m 
> <branch>" currently updates submodules whereas "git stash" does not know 
> how to recurse submodules.

Hmph, I do not do submodules outside what we already have, and I
certainly do not do "checkout --recurse-submodules" with or without
"-m" with local changes in our submodule.

But does "git stash" even need to know about recursing into
submodules for this?  When checkout recurses into a submodule, that
checkout that is working in the repository of the submodule can
handle "-m" itself, which may stash the local changes made in the
submodule, no?

> It would be nice to teach "git stash" to recurse submodules but I don't 
> think it is completly straight forward as we'd need to store the object 
> id of the submodule's stash commit in the parent stash.

No, let's not add more commands that take "--recurse-submodules", if
we do not have to.

Thanks.

Re: [PATCH] checkout: add --autostash option for branch switching

[Phillip Wood]

On 14/03/2026 17:17, Junio C Hamano wrote:
> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
>> On 12/03/2026 14:40, Junio C Hamano wrote:
>>>
>>> Perhaps doing it this way would make it more worth doing?
>>>
>>>    - At the beginning of branch switching, ask a new helper function
>>>      that takes the branch we are switching to as an argument this
>>>      question:
>>>
>>>      Do any paths that are different between the current branch and
>>>      the branch we are switching to have local (i.e., either in the
>>>      index or in the working tree) change [Yes/No]?
>>>
>>>    - When the answer is "yes", save the local changes to a new stash
>>>      entry, and clear the local changes from the index and from the
>>>      working tree.  If not, do not bother with stash at all.
>>
>> Can we avoid the extra check and stash if the user passed "--autostash"
>> and unpack_trees() fails because it would overwrite local changes in
>> merge_working_tree()?
> 
> Sorry, but I couldn't quite figure out what you are saying here.
> 
> My guess on one part of what it says is that an explicit
> "--autostash", we should stash without second guessing the user
> (i.e., avoid chedk and stash).  But then the latter part of the
> sentence "and unpack_trees() fails ..." do not quite parse.
> 
> If the user gave "--autostash" and we check with unpack_trees()
> dry-run and find out that a normal branch switch will be interfered
> by the local changes, then we would stash, but that check made by a
> dry-run unpack_trees() is not an "extra" check, so, that does not
> work as a guess of what you are saying, either.

Why is the dry-run of unpack_trees() not an extra check? I was assuming 
that it was because we do the dry-run and then do it for real after 
possibly stashing any local changes. That's why I was wondering if we 
could avoid the dry-run by creating the stash if the non-dry-run 
unpack_trees() failed. Looking at the unpack_trees() implementation it 
can fail for a variety of reasons, only some (one?) of which can be 
addressed by stashing local changes but there does not seem to be a way 
for the caller to determine what caused it to fail.

>>> If we can sell it as an improved implementation of "-m", we probably
>>> can lose some code that the current "-m" implementation uses to do
>>> its merge; we'd be instead using the "unstash" code paths.
>>
>> That would be nice but I think "git checkout --recurse-submodules -m
>> <branch>" currently updates submodules whereas "git stash" does not know
>> how to recurse submodules.
> 
> Hmph, I do not do submodules outside what we already have, and I
> certainly do not do "checkout --recurse-submodules" with or without
> "-m" with local changes in our submodule.
> 
> But does "git stash" even need to know about recursing into
> submodules for this?  When checkout recurses into a submodule, that
> checkout that is working in the repository of the submodule can
> handle "-m" itself, which may stash the local changes made in the
> submodule, no?

Oh, because this all happens in a single command then yes, I think we 
can. When I wrote that I'd been thinking about a recent question about 
rebase not recursing submodules on discord and what it would take to 
make "git rebase --recurse-submodules --autostash" work. There we need 
to be able to retrive the stash in a different process to the one that 
created it so we need some way of tracking the stashed changes in each 
submodule.

It turns out I'd misremembered what "git checkout -m 
--recurse-submodules" does at the moment - after testing it, it seems to 
simply nuke an uncommitted submodule changes rather than merging them.

Thanks

Phillip

>> It would be nice to teach "git stash" to recurse submodules but I don't
>> think it is completly straight forward as we'd need to store the object
>> id of the submodule's stash commit in the parent stash.
> 
> No, let's not add more commands that take "--recurse-submodules", if
> we do not have to.
> 
> Thanks.
> 

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Phillip Wood <phillip.wood123@gmail.com> writes:

> Why is the dry-run of unpack_trees() not an extra check? I was assuming 
> that it was because we do the dry-run and then do it for real after 
> possibly stashing any local changes. That's why I was wondering if we 
> could avoid the dry-run by creating the stash if the non-dry-run 
> unpack_trees() failed.

Ah, I didn't even think about that possibility.

Try to unpack anyway, and if unpack_trees() branch switching
succeeds, we are done.  Otherwise, we can trust that unpack_trees()
did not do _anything_ to the index or the working tree files, so we
can create the stash at that time.

Makes sense.

> It turns out I'd misremembered what "git checkout -m 
> --recurse-submodules" does at the moment - after testing it, it seems to 
> simply nuke an uncommitted submodule changes rather than merging them.

Makes sense.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

>> Why is the dry-run of unpack_trees() not an extra check? I was assuming 
>> that it was because we do the dry-run and then do it for real after 
>> possibly stashing any local changes. That's why I was wondering if we 
>> could avoid the dry-run by creating the stash if the non-dry-run 
>> unpack_trees() failed.
>
> Ah, I didn't even think about that possibility.
>
> Try to unpack anyway, and if unpack_trees() branch switching
> succeeds, we are done.  Otherwise, we can trust that unpack_trees()
> did not do _anything_ to the index or the working tree files, so we
> can create the stash at that time.
>
> Makes sense.

Interesting idea, and thanks for your help with this! I gave it a shot with
this simplification.

It passes the tests, which either means it works, or just that the test
coverage is not good enough to detect new issues introduced by me here.


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

Hi Junio and Jeff!

Did you get a chance to look at the latest changes?

The scope of this grew a lot from my original idea of auto-stashing, so I'm
not 100% convinced that changing '-m' is necessary here. My fear is to
break something, especially since 'checkout -m' is a feature I never used
before touching it here, so I don't have a good sense of how it should
work.


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Harald Nordgren <haraldnordgren@gmail.com> writes:

> Hi Junio and Jeff!
>
> Did you get a chance to look at the latest changes?
>
> The scope of this grew a lot from my original idea of auto-stashing, so I'm
> not 100% convinced that changing '-m' is necessary here. My fear is to
> break something, especially since 'checkout -m' is a feature I never used
> before touching it here, so I don't have a good sense of how it should
> work.

FWIW, I very much like what I see in 

   $ git checkout hn/git-checkout-m-with-stash && git diff @{1}

output.  It is great that we do not have to do any dry-run, because
the "real" run safely aborts, we can do the "stash && merge && unstash"
dance as a fallback instead.  All the credit goes to Phillip and you
for the idea and the execution of this.

I do use "checkout -m" a few times a week, but I do not do anything
complex with submodules or run the command with unrelated local
modifications, so there may be changes in behaviour I haven't seen
in corner cases that I do not exercise.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> FWIW, I very much like what I see in 
> 
>    $ git checkout hn/git-checkout-m-with-stash && git diff @{1}
> 
> output.  It is great that we do not have to do any dry-run, because
> the "real" run safely aborts, we can do the "stash && merge && unstash"
> dance as a fallback instead.  All the credit goes to Phillip and you
> for the idea and the execution of this.
> 
> I do use "checkout -m" a few times a week, but I do not do anything
> complex with submodules or run the command with unrelated local
> modifications, so there may be changes in behaviour I haven't seen
> in corner cases that I do not exercise.

I wonder if my implementation is not really up to par. I have ran into a
few "conflicts", were 'git stash pop' simply worked afterwards.

So not quite production ready.


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

>> FWIW, I very much like what I see in 
>> 
>>    $ git checkout hn/git-checkout-m-with-stash && git diff @{1}
>> 
>> output.  It is great that we do not have to do any dry-run, because
>> the "real" run safely aborts, we can do the "stash && merge && unstash"
>> dance as a fallback instead.  All the credit goes to Phillip and you
>> for the idea and the execution of this.
>> 
>> I do use "checkout -m" a few times a week, but I do not do anything
>> complex with submodules or run the command with unrelated local
>> modifications, so there may be changes in behaviour I haven't seen
>> in corner cases that I do not exercise.
>
> I wonder if my implementation is not really up to par. I have ran into a
> few "conflicts", were 'git stash pop' simply worked afterwards.
> 
> So not quite production ready.

Update on this: I realized that the issues I ran into was happening
because of a sub-shell, so it's resolved by running like this:

    export GIT_EXEC_PATH=/Users/Harald/git-repos/github.com/git/git && \
      /Users/Harald/git-repos/github.com/git/git/git checkout -m -

So thus, it's not a real problem.

I think this is ready to be reviewed, does anyone have time to take a look?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

>> FWIW, I very much like what I see in 
>> 
>>    $ git checkout hn/git-checkout-m-with-stash && git diff @{1}
>> 
>> output.  It is great that we do not have to do any dry-run, because
>> the "real" run safely aborts, we can do the "stash && merge && unstash"
>> dance as a fallback instead.  All the credit goes to Phillip and you
>> for the idea and the execution of this.
>> 
>> I do use "checkout -m" a few times a week, but I do not do anything
>> complex with submodules or run the command with unrelated local
>> modifications, so there may be changes in behaviour I haven't seen
>> in corner cases that I do not exercise.
>
> I wonder if my implementation is not really up to par. I have ran into a
> few "conflicts", were 'git stash pop' simply worked afterwards.
> 
> So not quite production ready.

Update on this: I realized that the issues I ran into was happening
because of a sub-shell, so it's resolved by running like this:

    export GIT_EXEC_PATH=/Users/Harald/git-repos/github.com/git/git && \
      /Users/Harald/git-repos/github.com/git/git/git checkout -m -

So thus, it's not a real problem.

I think this is ready to be reviewed, does anyone have time to take a look?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Harald Nordgren <haraldnordgren@gmail.com> writes:

> Update on this: I realized that the issues I ran into was happening
> because of a sub-shell, so it's resolved by running like this:
>
>     export GIT_EXEC_PATH=/Users/Harald/git-repos/github.com/git/git && \
>       /Users/Harald/git-repos/github.com/git/git/git checkout -m -
>
> So thus, it's not a real problem.

In other words, you were not consistently trying the version of Git
you just built?

Thanks for a good news.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> In other words, you were not consistently trying the version of Git
you just built?

I was, but the difference here is the this logic calls another instance of
Git halfway through, and I didn't realize until today that that other
instance ended up being the system Git instead. So technically, I was only
half-using it -- but accident.

Maybe I should consider installing it globally on my machine, via PATH or
otherwise!


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

>> FWIW, I very much like what I see in 
>> 
>>    $ git checkout hn/git-checkout-m-with-stash && git diff @{1}
>> 
>> output.  It is great that we do not have to do any dry-run, because
>> the "real" run safely aborts, we can do the "stash && merge && unstash"
>> dance as a fallback instead.  All the credit goes to Phillip and you
>> for the idea and the execution of this.
>> 
>> I do use "checkout -m" a few times a week, but I do not do anything
>> complex with submodules or run the command with unrelated local
>> modifications, so there may be changes in behaviour I haven't seen
>> in corner cases that I do not exercise.
>
> I wonder if my implementation is not really up to par. I have ran into a
> few "conflicts", were 'git stash pop' simply worked afterwards.
> 
> So not quite production ready.

Update on this: I realized that the issues I ran into was happening
because of a sub-shell, so it's resolved by running like this:

    export GIT_EXEC_PATH=/Users/Harald/git-repos/github.com/git/git && \
      /Users/Harald/git-repos/github.com/git/git/git checkout -m -

So thus, it's not a real problem.

I think this is ready to be reviewed, does anyone have time to take a look?


Harald

[PATCH v2] checkout: add --autostash option for branch switching

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches, local modifications in the working tree can
prevent the checkout from succeeding.  While "git rebase" and "git
merge" already support --autostash to handle this case automatically,
"git checkout" and "git switch" require users to manually stash and
unstash their changes.

Teach "git checkout" and "git switch" to accept --autostash and
--no-autostash options that automatically create a temporary stash
entry before the branch switch begins and apply it after the switch
completes.  If the stash application results in conflicts, the stash
entry is saved to the stash list so the user can resolve them later.

Also add a checkout.autoStash configuration option that enables this
behavior by default, which can be overridden with --no-autostash on
the command line.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: 'autostash' for branch switching

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v2
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v1:

 1:  12194f6fbe ! 1:  be2b697c54 checkout: add --autostash option for branch switching
     @@ Documentation/config/checkout.adoc: with a small number of cores, the default se
       well the parallel version performs.
       
      +`checkout.autoStash`::
     -+	When set to true, automatically create a temporary stash entry
     -+	before the operation begins, and apply it after the operation
     -+	ends.  This means that you can run `git checkout` or `git switch`
     -+	on a dirty worktree.  However, use with care: the final stash
     -+	application after a successful branch switch might result in
     -+	non-trivial conflicts.
     ++	When set to true, enable autostash for `git checkout` and
     ++	`git switch` branch switching operations.  When a branch
     ++	switch would fail because local changes (in the index or the
     ++	working tree) overlap with paths that differ between the
     ++	current and target branch, a temporary stash entry is
     ++	automatically created before the switch and applied after
     ++	it completes.  If the local changes do not overlap with the
     ++	branch difference, the switch proceeds normally without
     ++	stashing.
      +	This option can be overridden by the `--no-autostash` and
      +	`--autostash` options of linkgit:git-checkout[1] and
      +	linkgit:git-switch[1].
     @@ Documentation/git-checkout.adoc: When switching branches with `--merge`, staged
       
      +`--autostash`::
      +`--no-autostash`::
     -+	When switching branches, automatically create a temporary stash
     -+	entry before the operation begins, and apply it after the
     -+	operation ends.  This means that you can switch branches on a
     -+	dirty worktree.  However, use with care: the final stash
     -+	application after a successful branch switch might result in
     -+	non-trivial conflicts.
     ++	When switching branches, if any of the paths that differ
     ++	between the current branch and the target branch have local
     ++	changes (in the index or the working tree), automatically
     ++	create a temporary stash entry before the operation begins,
     ++	and apply it after the operation ends.  If the local changes
     ++	do not overlap with the branch difference, the switch proceeds
     ++	without stashing.  When a stash entry is created and the
     ++	subsequent application results in conflicts, the stash entry
     ++	is saved so that you can use `git stash pop` to recover and
     ++	`git stash drop` when done.  Use with `--force` to always
     ++	stash local changes regardless of conflicts.
      +
       `-p`::
       `--patch`::
     @@ Documentation/git-switch.adoc: should result in deletion of the path).
       
      +`--autostash`::
      +`--no-autostash`::
     -+	Automatically create a temporary stash entry before the
     -+	operation begins, and apply it after the operation ends.
     -+	This means that you can switch branches on a dirty worktree.
     -+	However, use with care: the final stash application after a
     -+	successful branch switch might result in non-trivial
     -+	conflicts.
     ++	When switching branches, if any of the paths that differ
     ++	between the current branch and the target branch have local
     ++	changes (in the index or the working tree), automatically
     ++	create a temporary stash entry before the operation begins,
     ++	and apply it after the operation ends.  If the local changes
     ++	do not overlap with the branch difference, the switch proceeds
     ++	without stashing.  When a stash entry is created and the
     ++	subsequent application results in conflicts, the stash entry
     ++	is saved so that you can use `git stash pop` to recover and
     ++	`git stash drop` when done.  Use with `--force` to always
     ++	stash local changes regardless of conflicts.
      +
       `-q`::
       `--quiet`::
     @@ builtin/checkout.c: struct checkout_opts {
       	int empty_pathspec_ok;
       	int checkout_index;
       	int checkout_worktree;
     +@@ builtin/checkout.c: static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
     + 	release_revisions(&revs);
     + }
     + 
     ++static int checkout_would_clobber_changes(struct branch_info *old_branch_info,
     ++					  struct branch_info *new_branch_info)
     ++{
     ++	struct tree_desc trees[2];
     ++	struct tree *old_tree, *new_tree;
     ++	struct unpack_trees_options topts;
     ++	struct index_state tmp_index = INDEX_STATE_INIT(the_repository);
     ++	const struct object_id *old_commit_oid;
     ++	int ret;
     ++
     ++	if (!new_branch_info->commit)
     ++		return 0;
     ++
     ++	old_commit_oid = old_branch_info->commit ?
     ++		&old_branch_info->commit->object.oid :
     ++		the_hash_algo->empty_tree;
     ++	old_tree = repo_parse_tree_indirect(the_repository, old_commit_oid);
     ++	if (!old_tree)
     ++		return 0;
     ++
     ++	new_tree = repo_get_commit_tree(the_repository,
     ++					new_branch_info->commit);
     ++	if (!new_tree)
     ++		return 0;
     ++	if (repo_parse_tree(the_repository, new_tree) < 0)
     ++		return 0;
     ++
     ++	memset(&topts, 0, sizeof(topts));
     ++	topts.head_idx = -1;
     ++	topts.src_index = the_repository->index;
     ++	topts.dst_index = &tmp_index;
     ++	topts.initial_checkout = is_index_unborn(the_repository->index);
     ++	topts.merge = 1;
     ++	topts.update = 1;
     ++	topts.dry_run = 1;
     ++	topts.quiet = 1;
     ++	topts.fn = twoway_merge;
     ++
     ++	init_tree_desc(&trees[0], &old_tree->object.oid,
     ++		       old_tree->buffer, old_tree->size);
     ++	init_tree_desc(&trees[1], &new_tree->object.oid,
     ++		       new_tree->buffer, new_tree->size);
     ++
     ++	ret = unpack_trees(2, trees, &topts);
     ++	discard_index(&tmp_index);
     ++
     ++	return ret != 0;
     ++}
     ++
     + static int switch_branches(const struct checkout_opts *opts,
     + 			   struct branch_info *new_branch_info)
     + {
      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       			do_merge = 0;
       	}
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +	if (opts->autostash) {
      +		if (repo_read_index(the_repository) < 0)
      +			die(_("index file corrupt"));
     -+		create_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
     ++		if (opts->discard_changes ||
     ++		    checkout_would_clobber_changes(&old_branch_info,
     ++						   new_branch_info))
     ++			create_autostash_ref(the_repository,
     ++					     "CHECKOUT_AUTOSTASH");
      +	}
      +
       	if (do_merge) {
     @@ t/t2061-switch-autostash.sh (new)
      +	git checkout main
      +'
      +
     -+test_expect_success 'switch --autostash on dirty worktree' '
     ++test_expect_success 'switch --autostash skips stash when no conflict' '
      +	git branch branch1 other-branch &&
      +	echo dirty >file0 &&
      +	git switch --autostash branch1 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty >expected &&
      +	test_cmp expected file0 &&
      +	git switch main
      +'
      +
     -+test_expect_success 'checkout --autostash on dirty worktree' '
     ++test_expect_success 'checkout --autostash skips stash when no conflict' '
      +	git branch branch2 other-branch &&
      +	echo dirty >file0 &&
      +	git checkout --autostash branch2 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty >expected &&
      +	test_cmp expected file0 &&
      +	git checkout main
      +'
      +
     -+test_expect_success 'switch: checkout.autostash config' '
     ++test_expect_success 'switch: checkout.autostash config skips stash when no conflict' '
      +	git branch branch3 other-branch &&
      +	echo dirty >file0 &&
      +	test_config checkout.autostash true &&
      +	git switch branch3 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty >expected &&
      +	test_cmp expected file0 &&
      +	git switch main
      +'
      +
     -+test_expect_success 'checkout: checkout.autostash config' '
     ++test_expect_success 'checkout: checkout.autostash config skips stash when no conflict' '
      +	git branch branch4 other-branch &&
      +	echo dirty >file0 &&
      +	test_config checkout.autostash true &&
      +	git checkout branch4 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty >expected &&
      +	test_cmp expected file0 &&
      +	git checkout main
     @@ t/t2061-switch-autostash.sh (new)
      +	echo dirty >file0 &&
      +	test_config checkout.autostash false &&
      +	git switch --autostash branch6 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty >expected &&
      +	test_cmp expected file0 &&
      +	git switch main
      +'
      +
     -+test_expect_success 'autostash with dirty index' '
     ++test_expect_success 'autostash with non-conflicting dirty index' '
      +	git branch branch7 other-branch &&
      +	echo dirty-index >file0 &&
      +	git add file0 &&
      +	git switch --autostash branch7 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty-index >expected &&
      +	test_cmp expected file0 &&
      +	git checkout -- file0 &&
     @@ t/t2061-switch-autostash.sh (new)
      +	git switch main
      +'
      +
     -+test_expect_success '--autostash with --merge stashes and switches' '
     ++test_expect_success '--autostash with --merge skips stash when no conflict' '
      +	git branch branch10 other-branch &&
      +	echo dirty >file0 &&
      +	git switch --autostash --merge branch10 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty >expected &&
      +	test_cmp expected file0 &&
      +	git switch main
     @@ t/t2061-switch-autostash.sh (new)
      +	git switch main
      +'
      +
     -+test_expect_success '--autostash with new branch creation' '
     ++test_expect_success '--autostash with new branch creation skips stash' '
      +	echo dirty >file0 &&
      +	git switch --autostash -c branch13 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	echo dirty >expected &&
      +	test_cmp expected file0 &&
      +	git switch main &&
      +	git branch -D branch13
      +'
      +
     ++test_expect_success 'autostash with conflicting changes that apply cleanly' '
     ++	git branch branch14 other-branch &&
     ++	echo file1other >file1 &&
     ++	git switch --autostash branch14 >actual 2>&1 &&
     ++	test_grep "Created autostash" actual &&
     ++	test_grep "Applied autostash" actual &&
     ++	echo file1other >expected &&
     ++	test_cmp expected file1 &&
     ++	git switch main
     ++'
     ++
      +test_done
      
       ## t/t9902-completion.sh ##


 Documentation/config/checkout.adoc |  15 +++
 Documentation/git-checkout.adoc    |  14 +++
 Documentation/git-switch.adoc      |  14 +++
 builtin/checkout.c                 |  69 +++++++++++
 t/meson.build                      |   1 +
 t/t2061-switch-autostash.sh        | 184 +++++++++++++++++++++++++++++
 t/t9902-completion.sh              |   1 +
 7 files changed, 298 insertions(+)
 create mode 100755 t/t2061-switch-autostash.sh

diff --git a/Documentation/config/checkout.adoc b/Documentation/config/checkout.adoc
index e35d212969..268b7b1b8b 100644
--- a/Documentation/config/checkout.adoc
+++ b/Documentation/config/checkout.adoc
@@ -36,6 +36,21 @@ with a small number of cores, the default sequential checkout often performs
 better. The size and compression level of a repository might also influence how
 well the parallel version performs.
 
+`checkout.autoStash`::
+	When set to true, enable autostash for `git checkout` and
+	`git switch` branch switching operations.  When a branch
+	switch would fail because local changes (in the index or the
+	working tree) overlap with paths that differ between the
+	current and target branch, a temporary stash entry is
+	automatically created before the switch and applied after
+	it completes.  If the local changes do not overlap with the
+	branch difference, the switch proceeds normally without
+	stashing.
+	This option can be overridden by the `--no-autostash` and
+	`--autostash` options of linkgit:git-checkout[1] and
+	linkgit:git-switch[1].
+	Defaults to false.
+
 `checkout.thresholdForParallelism`::
 	When running parallel checkout with a small number of files, the cost
 	of subprocess spawning and inter-process communication might outweigh
diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..19da63c5be 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -272,6 +272,20 @@ When switching branches with `--merge`, staged changes may be lost.
 	`merge.conflictStyle` configuration variable.  Possible values are
 	`merge` (default), `diff3`, and `zdiff3`.
 
+`--autostash`::
+`--no-autostash`::
+	When switching branches, if any of the paths that differ
+	between the current branch and the target branch have local
+	changes (in the index or the working tree), automatically
+	create a temporary stash entry before the operation begins,
+	and apply it after the operation ends.  If the local changes
+	do not overlap with the branch difference, the switch proceeds
+	without stashing.  When a stash entry is created and the
+	subsequent application results in conflicts, the stash entry
+	is saved so that you can use `git stash pop` to recover and
+	`git stash drop` when done.  Use with `--force` to always
+	stash local changes regardless of conflicts.
+
 `-p`::
 `--patch`::
 	Interactively select hunks in the difference between the
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..6028479fef 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -142,6 +142,20 @@ should result in deletion of the path).
 	`merge.conflictStyle` configuration variable.  Possible values are
 	`merge` (default), `diff3`, and `zdiff3`.
 
+`--autostash`::
+`--no-autostash`::
+	When switching branches, if any of the paths that differ
+	between the current branch and the target branch have local
+	changes (in the index or the working tree), automatically
+	create a temporary stash entry before the operation begins,
+	and apply it after the operation ends.  If the local changes
+	do not overlap with the branch difference, the switch proceeds
+	without stashing.  When a stash entry is created and the
+	subsequent application results in conflicts, the stash entry
+	is saved so that you can use `git stash pop` to recover and
+	`git stash drop` when done.  Use with `--force` to always
+	stash local changes regardless of conflicts.
+
 `-q`::
 `--quiet`::
 	Quiet, suppress feedback messages.
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 1d1667fa4c..4a251a8732 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,6 +30,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -68,6 +69,7 @@ struct checkout_opts {
 	int only_merge_on_switching_branches;
 	int can_switch_when_in_progress;
 	int orphan_from_empty_tree;
+	int autostash;
 	int empty_pathspec_ok;
 	int checkout_index;
 	int checkout_worktree;
@@ -1157,6 +1159,55 @@ static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
 	release_revisions(&revs);
 }
 
+static int checkout_would_clobber_changes(struct branch_info *old_branch_info,
+					  struct branch_info *new_branch_info)
+{
+	struct tree_desc trees[2];
+	struct tree *old_tree, *new_tree;
+	struct unpack_trees_options topts;
+	struct index_state tmp_index = INDEX_STATE_INIT(the_repository);
+	const struct object_id *old_commit_oid;
+	int ret;
+
+	if (!new_branch_info->commit)
+		return 0;
+
+	old_commit_oid = old_branch_info->commit ?
+		&old_branch_info->commit->object.oid :
+		the_hash_algo->empty_tree;
+	old_tree = repo_parse_tree_indirect(the_repository, old_commit_oid);
+	if (!old_tree)
+		return 0;
+
+	new_tree = repo_get_commit_tree(the_repository,
+					new_branch_info->commit);
+	if (!new_tree)
+		return 0;
+	if (repo_parse_tree(the_repository, new_tree) < 0)
+		return 0;
+
+	memset(&topts, 0, sizeof(topts));
+	topts.head_idx = -1;
+	topts.src_index = the_repository->index;
+	topts.dst_index = &tmp_index;
+	topts.initial_checkout = is_index_unborn(the_repository->index);
+	topts.merge = 1;
+	topts.update = 1;
+	topts.dry_run = 1;
+	topts.quiet = 1;
+	topts.fn = twoway_merge;
+
+	init_tree_desc(&trees[0], &old_tree->object.oid,
+		       old_tree->buffer, old_tree->size);
+	init_tree_desc(&trees[1], &new_tree->object.oid,
+		       new_tree->buffer, new_tree->size);
+
+	ret = unpack_trees(2, trees, &topts);
+	discard_index(&tmp_index);
+
+	return ret != 0;
+}
+
 static int switch_branches(const struct checkout_opts *opts,
 			   struct branch_info *new_branch_info)
 {
@@ -1202,9 +1253,20 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (opts->autostash) {
+		if (repo_read_index(the_repository) < 0)
+			die(_("index file corrupt"));
+		if (opts->discard_changes ||
+		    checkout_would_clobber_changes(&old_branch_info,
+						   new_branch_info))
+			create_autostash_ref(the_repository,
+					     "CHECKOUT_AUTOSTASH");
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 		if (ret) {
+			apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
 			branch_info_release(&old_branch_info);
 			return ret;
 		}
@@ -1215,6 +1277,8 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
 
@@ -1236,6 +1300,10 @@ static int git_checkout_config(const char *var, const char *value,
 		opts->dwim_new_local_branch = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "checkout.autostash")) {
+		opts->autostash = git_config_bool(var, value);
+		return 0;
+	}
 
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
@@ -1745,6 +1813,7 @@ static struct option *add_common_switch_branch_options(
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
 			 N_("do not check if another worktree is using this branch")),
+		OPT_AUTOSTASH(&opts->autostash),
 		OPT_END()
 	};
 	struct option *newopts = parse_options_concat(prevopts, options);
diff --git a/t/meson.build b/t/meson.build
index f66a73f8a0..0645253d25 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -275,6 +275,7 @@ integration_tests = [
   't2030-unresolve-info.sh',
   't2050-git-dir-relative.sh',
   't2060-switch.sh',
+  't2061-switch-autostash.sh',
   't2070-restore.sh',
   't2071-restore-patch.sh',
   't2072-restore-pathspec-file.sh',
diff --git a/t/t2061-switch-autostash.sh b/t/t2061-switch-autostash.sh
new file mode 100755
index 0000000000..d37d6f4b8b
--- /dev/null
+++ b/t/t2061-switch-autostash.sh
@@ -0,0 +1,184 @@
+#!/bin/sh
+
+test_description='checkout/switch --autostash tests'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	echo file0content >file0 &&
+	echo file1content >file1 &&
+	git add . &&
+	test_tick &&
+	git commit -m "initial commit" &&
+	git branch other-branch &&
+	echo file1main >file1 &&
+	git add . &&
+	test_tick &&
+	git commit -m "modify file1 on main" &&
+	git checkout other-branch &&
+	echo file1other >file1 &&
+	git add . &&
+	test_tick &&
+	git commit -m "modify file1 on other-branch" &&
+	echo file2content >file2 &&
+	git add . &&
+	test_tick &&
+	git commit -m "add file2 on other-branch" &&
+	git checkout main
+'
+
+test_expect_success 'switch --autostash skips stash when no conflict' '
+	git branch branch1 other-branch &&
+	echo dirty >file0 &&
+	git switch --autostash branch1 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'checkout --autostash skips stash when no conflict' '
+	git branch branch2 other-branch &&
+	echo dirty >file0 &&
+	git checkout --autostash branch2 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git checkout main
+'
+
+test_expect_success 'switch: checkout.autostash config skips stash when no conflict' '
+	git branch branch3 other-branch &&
+	echo dirty >file0 &&
+	test_config checkout.autostash true &&
+	git switch branch3 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'checkout: checkout.autostash config skips stash when no conflict' '
+	git branch branch4 other-branch &&
+	echo dirty >file0 &&
+	test_config checkout.autostash true &&
+	git checkout branch4 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git checkout main
+'
+
+test_expect_success '--no-autostash overrides checkout.autostash' '
+	git branch branch5 other-branch &&
+	echo dirty >file1 &&
+	test_config checkout.autostash true &&
+	test_must_fail git switch --no-autostash branch5 2>stderr &&
+	test_grep ! "Created autostash" stderr &&
+	git checkout -- file1
+'
+
+test_expect_success '--autostash overrides checkout.autostash=false' '
+	git branch branch6 other-branch &&
+	echo dirty >file0 &&
+	test_config checkout.autostash false &&
+	git switch --autostash branch6 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'autostash with non-conflicting dirty index' '
+	git branch branch7 other-branch &&
+	echo dirty-index >file0 &&
+	git add file0 &&
+	git switch --autostash branch7 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty-index >expected &&
+	test_cmp expected file0 &&
+	git checkout -- file0 &&
+	git switch main
+'
+
+test_expect_success 'autostash bypasses conflicting local changes' '
+	git branch branch8 other-branch &&
+	echo dirty >file1 &&
+	test_must_fail git switch branch8 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git switch --autostash branch8 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard &&
+	git switch main
+'
+
+test_expect_success 'autostash is a no-op with clean worktree' '
+	git branch branch9 other-branch &&
+	git switch --autostash branch9 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git switch main
+'
+
+test_expect_success '--autostash with --merge skips stash when no conflict' '
+	git branch branch10 other-branch &&
+	echo dirty >file0 &&
+	git switch --autostash --merge branch10 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main
+'
+
+test_expect_success 'autostash with staged conflicting changes' '
+	git branch branch11 other-branch &&
+	echo staged-change >file1 &&
+	git add file1 &&
+	git switch --autostash branch11 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard &&
+	git switch main
+'
+
+test_expect_success '--autostash with --force preserves dirty changes' '
+	git branch branch12 other-branch &&
+	echo dirty-force >file1 &&
+	git switch --autostash --force branch12 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard &&
+	git switch main
+'
+
+test_expect_success '--autostash with new branch creation skips stash' '
+	echo dirty >file0 &&
+	git switch --autostash -c branch13 >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	echo dirty >expected &&
+	test_cmp expected file0 &&
+	git switch main &&
+	git branch -D branch13
+'
+
+test_expect_success 'autostash with conflicting changes that apply cleanly' '
+	git branch branch14 other-branch &&
+	echo file1other >file1 &&
+	git switch --autostash branch14 >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	echo file1other >expected &&
+	test_cmp expected file1 &&
+	git switch main
+'
+
+test_done
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 2f9a597ec7..f33ca543a9 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -2602,6 +2602,7 @@ test_expect_success 'double dash "git checkout"' '
 	--ignore-other-worktrees Z
 	--recurse-submodules Z
 	--auto-advance Z
+	--autostash Z
 	--progress Z
 	--guess Z
 	--no-guess Z

base-commit: 7f19e4e1b6a3ad259e2ed66033e01e03b8b74c5e
-- 
gitgitgadget

Re: [PATCH v2] checkout: add --autostash option for branch switching

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> When switching branches, local modifications in the working tree can
> prevent the checkout from succeeding.  While "git rebase" and "git
> merge" already support --autostash to handle this case automatically,
> "git checkout" and "git switch" require users to manually stash and
> unstash their changes.
>
> Teach "git checkout" and "git switch" to accept --autostash and
> --no-autostash options that automatically create a temporary stash
> entry before the branch switch begins and apply it after the switch
> completes.  If the stash application results in conflicts, the stash
> entry is saved to the stash list so the user can resolve them later.
>
> Also add a checkout.autoStash configuration option that enables this
> behavior by default, which can be overridden with --no-autostash on
> the command line.

With this, shouldn't "-m" become a synonym for "--autostash"?
For users of "checkout -m", this is a strictly improved version of
the same feature, it seems.

Also, "stash" is merely an implementation detail of how we make the
merge safer, so from end-user's point of view, this feature is more
like "switch to the other branch, while merging the local changes
there", so calling it "--merge" or something may be much better than
calling it "--autostash".

Other than that, I like the implementation in general.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> With this, shouldn't "-m" become a synonym for "--autostash"?
> For users of "checkout -m", this is a strictly improved version of
> the same feature, it seems.
>
> Also, "stash" is merely an implementation detail of how we make the
> merge safer, so from end-user's point of view, this feature is more
> like "switch to the other branch, while merging the local changes
> there", so calling it "--merge" or something may be much better than
> calling it "--autostash".

That's an interesting idea and I gave it a shot! I do worry about breaking
the existing '-m' flow because I don't understand its fundamentals.

But tests old seem to be passing (well, they did break and then I fixed the
code to make them pass again), so that's promising. Although hard for me to
say if the old test coverage protects against all possible regressions.

> Other than that, I like the implementation in general.

Thanks for all your support, Junio!


Harald

[PATCH v3] checkout: add --autostash option for branch switching

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches, local modifications in the working tree can
prevent the checkout from succeeding.  While "git rebase" and "git
merge" already support --autostash to handle this case automatically,
"git checkout" and "git switch" require users to manually stash and
unstash their changes.

Teach "git checkout" and "git switch" to accept --autostash and
--no-autostash options that automatically create a temporary stash
entry before the branch switch begins and apply it after the switch
completes.  If the stash application results in conflicts, the stash
entry is saved to the stash list so the user can resolve them later.

Also add a checkout.autoStash configuration option that enables this
behavior by default, which can be overridden with --no-autostash on
the command line.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: 'autostash' for branch switching

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v3
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v2:

 1:  be2b697c54 ! 1:  05f1e53163 checkout: add --autostash option for branch switching
     @@ Commit message
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     - ## Documentation/config/checkout.adoc ##
     -@@ Documentation/config/checkout.adoc: with a small number of cores, the default sequential checkout often performs
     - better. The size and compression level of a repository might also influence how
     - well the parallel version performs.
     - 
     -+`checkout.autoStash`::
     -+	When set to true, enable autostash for `git checkout` and
     -+	`git switch` branch switching operations.  When a branch
     -+	switch would fail because local changes (in the index or the
     -+	working tree) overlap with paths that differ between the
     -+	current and target branch, a temporary stash entry is
     -+	automatically created before the switch and applied after
     -+	it completes.  If the local changes do not overlap with the
     -+	branch difference, the switch proceeds normally without
     -+	stashing.
     -+	This option can be overridden by the `--no-autostash` and
     -+	`--autostash` options of linkgit:git-checkout[1] and
     -+	linkgit:git-switch[1].
     -+	Defaults to false.
     -+
     - `checkout.thresholdForParallelism`::
     - 	When running parallel checkout with a small number of files, the cost
     - 	of subprocess spawning and inter-process communication might outweigh
     -
       ## Documentation/git-checkout.adoc ##
     -@@ Documentation/git-checkout.adoc: When switching branches with `--merge`, staged changes may be lost.
     - 	`merge.conflictStyle` configuration variable.  Possible values are
     - 	`merge` (default), `diff3`, and `zdiff3`.
     +@@ Documentation/git-checkout.adoc: working tree, by copying them from elsewhere, extracting a tarball, etc.
     + 	are different between the current branch and the branch to
     + 	which you are switching, the command refuses to switch
     + 	branches in order to preserve your modifications in context.
     +-	However, with this option, a three-way merge between the current
     +-	branch, your working tree contents, and the new branch
     +-	is done, and you will be on the new branch.
     +-+
     +-When a merge conflict happens, the index entries for conflicting
     +-paths are left unmerged, and you need to resolve the conflicts
     +-and mark the resolved paths with `git add` (or `git rm` if the merge
     +-should result in deletion of the path).
     ++	With this option, the conflicting local changes are
     ++	automatically stashed before the switch and reapplied
     ++	afterwards.  If the local changes do not overlap with the
     ++	differences between branches, the switch proceeds without
     ++	stashing.  If reapplying the stash results in conflicts, the
     ++	entry is saved to the stash list so you can use `git stash
     ++	pop` to recover and `git stash drop` when done.
     + +
     + When checking out paths from the index, this option lets you recreate
     + the conflicted merge in the specified paths.  This option cannot be
     + used when checking out paths from a tree-ish.
     +-+
     +-When switching branches with `--merge`, staged changes may be lost.
     + 
     + `--conflict=<style>`::
     + 	The same as `--merge` option above, but changes the way the
     +@@ Documentation/git-checkout.adoc: $ git checkout mytopic
     + error: You have local changes to 'frotz'; not switching branches.
     + ------------
     + 
     +-You can give the `-m` flag to the command, which would try a
     +-three-way merge:
     ++You can give the `-m` flag to the command, which would save the local
     ++changes in a stash entry and reset the working tree to allow switching:
     + 
     + ------------
     + $ git checkout -m mytopic
     +-Auto-merging frotz
     ++Created autostash: 7a9afa3
     ++Applied autostash.
     + ------------
     + 
     +-After this three-way merge, the local modifications are _not_
     ++After the switch, the local modifications are reapplied and are _not_
     + registered in your index file, so `git diff` would show you what
     + changes you made since the tip of the new branch.
     + 
     + === 3. Merge conflict
     + 
     +-When a merge conflict happens during switching branches with
     +-the `-m` option, you would see something like this:
     ++When the locally modified files overlap with files that need to be
     ++updated by the branch switch, the changes are stashed and reapplied
     ++after the switch.  If the stash application results in conflicts,
     ++they are not resolved and the stash is saved to the stash list:
     + 
     + ------------
     + $ git checkout -m mytopic
     +-Auto-merging frotz
     +-ERROR: Merge conflict in frotz
     +-fatal: merge program failed
     ++Created autostash: 7a9afa3
     ++Applying autostash resulted in conflicts.
     ++Your changes are safe in the stash.
     ++You can run "git stash pop" or "git stash drop" at any time.
     + ------------
       
     -+`--autostash`::
     -+`--no-autostash`::
     -+	When switching branches, if any of the paths that differ
     -+	between the current branch and the target branch have local
     -+	changes (in the index or the working tree), automatically
     -+	create a temporary stash entry before the operation begins,
     -+	and apply it after the operation ends.  If the local changes
     -+	do not overlap with the branch difference, the switch proceeds
     -+	without stashing.  When a stash entry is created and the
     -+	subsequent application results in conflicts, the stash entry
     -+	is saved so that you can use `git stash pop` to recover and
     -+	`git stash drop` when done.  Use with `--force` to always
     -+	stash local changes regardless of conflicts.
     -+
     - `-p`::
     - `--patch`::
     - 	Interactively select hunks in the difference between the
     +-At this point, `git diff` shows the changes cleanly merged as in
     +-the previous example, as well as the changes in the conflicted
     +-files.  Edit and resolve the conflict and mark it resolved with
     +-`git add` as usual:
     +-
     +-------------
     +-$ edit frotz
     +-$ git add frotz
     +-------------
     ++At this point, `git stash pop` can be used to recover and resolve
     ++the conflicts, and `git stash drop` to discard the stash when done.
     + 
     + CONFIGURATION
     + -------------
      
       ## Documentation/git-switch.adoc ##
     -@@ Documentation/git-switch.adoc: should result in deletion of the path).
     - 	`merge.conflictStyle` configuration variable.  Possible values are
     - 	`merge` (default), `diff3`, and `zdiff3`.
     +@@ Documentation/git-switch.adoc: variable.
     + 	If you have local modifications to one or more files that are
     + 	different between the current branch and the branch to which
     + 	you are switching, the command refuses to switch branches in
     +-	order to preserve your modifications in context.  However,
     +-	with this option, a three-way merge between the current
     +-	branch, your working tree contents, and the new branch is
     +-	done, and you will be on the new branch.
     +-+
     +-When a merge conflict happens, the index entries for conflicting
     +-paths are left unmerged, and you need to resolve the conflicts
     +-and mark the resolved paths with `git add` (or `git rm` if the merge
     +-should result in deletion of the path).
     ++	order to preserve your modifications in context.  With this
     ++	option, the conflicting local changes are automatically
     ++	stashed before the switch and reapplied afterwards.  If the
     ++	local changes do not overlap with the differences between
     ++	branches, the switch proceeds without stashing.  If
     ++	reapplying the stash results in conflicts, the entry is
     ++	saved to the stash list so you can use `git stash pop` to
     ++	recover and `git stash drop` when done.
     + 
     + `--conflict=<style>`::
     + 	The same as `--merge` option above, but changes the way the
     +@@ Documentation/git-switch.adoc: $ git switch mytopic
     + error: You have local changes to 'frotz'; not switching branches.
     + ------------
     + 
     +-You can give the `-m` flag to the command, which would try a three-way
     +-merge:
     ++You can give the `-m` flag to the command, which would save the local
     ++changes in a stash entry and reset the working tree to allow switching:
     + 
     + ------------
     + $ git switch -m mytopic
     +-Auto-merging frotz
     ++Created autostash: 7a9afa3
     ++Applied autostash.
     + ------------
     + 
     +-After this three-way merge, the local modifications are _not_
     ++After the switch, the local modifications are reapplied and are _not_
     + registered in your index file, so `git diff` would show you what
     + changes you made since the tip of the new branch.
       
     -+`--autostash`::
     -+`--no-autostash`::
     -+	When switching branches, if any of the paths that differ
     -+	between the current branch and the target branch have local
     -+	changes (in the index or the working tree), automatically
     -+	create a temporary stash entry before the operation begins,
     -+	and apply it after the operation ends.  If the local changes
     -+	do not overlap with the branch difference, the switch proceeds
     -+	without stashing.  When a stash entry is created and the
     -+	subsequent application results in conflicts, the stash entry
     -+	is saved so that you can use `git stash pop` to recover and
     -+	`git stash drop` when done.  Use with `--force` to always
     -+	stash local changes regardless of conflicts.
     -+
     - `-q`::
     - `--quiet`::
     - 	Quiet, suppress feedback messages.
      
       ## builtin/checkout.c ##
     +@@
     + #include "merge-ll.h"
     + #include "lockfile.h"
     + #include "mem-pool.h"
     +-#include "merge-ort-wrappers.h"
     + #include "object-file.h"
     + #include "object-name.h"
     + #include "odb.h"
      @@
       #include "repo-settings.h"
       #include "resolve-undo.h"
     @@ builtin/checkout.c
       #include "setup.h"
       #include "submodule.h"
       #include "symlinks.h"
     -@@ builtin/checkout.c: struct checkout_opts {
     - 	int only_merge_on_switching_branches;
     - 	int can_switch_when_in_progress;
     - 	int orphan_from_empty_tree;
     -+	int autostash;
     - 	int empty_pathspec_ok;
     - 	int checkout_index;
     - 	int checkout_worktree;
     +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     + 
     + 		ret = unpack_trees(2, trees, &topts);
     + 		clear_unpack_trees_porcelain(&topts);
     +-		if (ret == -1) {
     +-			/*
     +-			 * Unpack couldn't do a trivial merge; either
     +-			 * give up or do a real merge, depending on
     +-			 * whether the merge flag was used.
     +-			 */
     +-			struct tree *work;
     +-			struct tree *old_tree;
     +-			struct merge_options o;
     +-			struct strbuf sb = STRBUF_INIT;
     +-			struct strbuf old_commit_shortname = STRBUF_INIT;
     +-
     +-			if (!opts->merge)
     +-				return 1;
     +-
     +-			/*
     +-			 * Without old_branch_info->commit, the below is the same as
     +-			 * the two-tree unpack we already tried and failed.
     +-			 */
     +-			if (!old_branch_info->commit)
     +-				return 1;
     +-			old_tree = repo_get_commit_tree(the_repository,
     +-							old_branch_info->commit);
     +-
     +-			if (repo_index_has_changes(the_repository, old_tree, &sb))
     +-				die(_("cannot continue with staged changes in "
     +-				      "the following files:\n%s"), sb.buf);
     +-			strbuf_release(&sb);
     +-
     +-			/* Do more real merge */
     +-
     +-			/*
     +-			 * We update the index fully, then write the
     +-			 * tree from the index, then merge the new
     +-			 * branch with the current tree, with the old
     +-			 * branch as the base. Then we reset the index
     +-			 * (but not the working tree) to the new
     +-			 * branch, leaving the working tree as the
     +-			 * merged version, but skipping unmerged
     +-			 * entries in the index.
     +-			 */
     +-
     +-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
     +-					0, 0);
     +-			init_ui_merge_options(&o, the_repository);
     +-			o.verbosity = 0;
     +-			work = write_in_core_index_as_tree(the_repository);
     +-
     +-			ret = reset_tree(new_tree,
     +-					 opts, 1,
     +-					 writeout_error, new_branch_info);
     +-			if (ret)
     +-				return ret;
     +-			o.ancestor = old_branch_info->name;
     +-			if (!old_branch_info->name) {
     +-				strbuf_add_unique_abbrev(&old_commit_shortname,
     +-							 &old_branch_info->commit->object.oid,
     +-							 DEFAULT_ABBREV);
     +-				o.ancestor = old_commit_shortname.buf;
     +-			}
     +-			o.branch1 = new_branch_info->name;
     +-			o.branch2 = "local";
     +-			o.conflict_style = opts->conflict_style;
     +-			ret = merge_ort_nonrecursive(&o,
     +-						     new_tree,
     +-						     work,
     +-						     old_tree);
     +-			if (ret < 0)
     +-				die(NULL);
     +-			ret = reset_tree(new_tree,
     +-					 opts, 0,
     +-					 writeout_error, new_branch_info);
     +-			strbuf_release(&o.obuf);
     +-			strbuf_release(&old_commit_shortname);
     +-			if (ret)
     +-				return ret;
     +-		}
     ++		if (ret == -1)
     ++			return 1;
     + 	}
     + 
     + 	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
     +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     + 	if (write_locked_index(the_repository->index, &lock_file, COMMIT_LOCK))
     + 		die(_("unable to write new index file"));
     + 
     +-	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
     +-		show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
     +-
     + 	return 0;
     + }
     + 
      @@ builtin/checkout.c: static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
       	release_revisions(&revs);
       }
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       			do_merge = 0;
       	}
       
     -+	if (opts->autostash) {
     ++	if (opts->merge) {
      +		if (repo_read_index(the_repository) < 0)
      +			die(_("index file corrupt"));
     -+		if (opts->discard_changes ||
     -+		    checkout_would_clobber_changes(&old_branch_info,
     ++		if (checkout_would_clobber_changes(&old_branch_info,
      +						   new_branch_info))
      +			create_autostash_ref(the_repository,
      +					     "CHECKOUT_AUTOSTASH");
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       
       	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
       
     ++	if (opts->conflict_style >= 0) {
     ++		struct strbuf cfg = STRBUF_INIT;
     ++		strbuf_addf(&cfg, "merge.conflictStyle=%s",
     ++			    conflict_style_name(opts->conflict_style));
     ++		git_config_push_parameter(cfg.buf);
     ++		strbuf_release(&cfg);
     ++	}
      +	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
     ++
     ++	discard_index(the_repository->index);
     ++	if (repo_read_index(the_repository) < 0)
     ++		die(_("index file corrupt"));
     ++
     ++	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
     ++		show_local_changes(&new_branch_info->commit->object,
     ++				   &opts->diff_options);
      +
       	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
       	branch_info_release(&old_branch_info);
       
     -@@ builtin/checkout.c: static int git_checkout_config(const char *var, const char *value,
     - 		opts->dwim_new_local_branch = git_config_bool(var, value);
     - 		return 0;
     - 	}
     -+	if (!strcmp(var, "checkout.autostash")) {
     -+		opts->autostash = git_config_bool(var, value);
     -+		return 0;
     -+	}
     - 
     - 	if (starts_with(var, "submodule."))
     - 		return git_default_submodule_config(var, value, NULL);
     -@@ builtin/checkout.c: static struct option *add_common_switch_branch_options(
     - 			   PARSE_OPT_NOCOMPLETE),
     - 		OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
     - 			 N_("do not check if another worktree is using this branch")),
     -+		OPT_AUTOSTASH(&opts->autostash),
     - 		OPT_END()
     - 	};
     - 	struct option *newopts = parse_options_concat(prevopts, options);
      
     - ## t/meson.build ##
     -@@ t/meson.build: integration_tests = [
     -   't2030-unresolve-info.sh',
     -   't2050-git-dir-relative.sh',
     -   't2060-switch.sh',
     -+  't2061-switch-autostash.sh',
     -   't2070-restore.sh',
     -   't2071-restore-patch.sh',
     -   't2072-restore-pathspec-file.sh',
     + ## sequencer.c ##
     +@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     + 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
     + 		}
     + 
     +-		printf(_("Created autostash: %s\n"), buf.buf);
     ++		fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
     + 		if (reset_head(r, &ropts) < 0)
     + 			die(_("could not reset --hard"));
     + 		discard_index(r->index);
      
     - ## t/t2061-switch-autostash.sh (new) ##
     -@@
     -+#!/bin/sh
     -+
     -+test_description='checkout/switch --autostash tests'
     -+
     -+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
     -+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
     -+
     -+. ./test-lib.sh
     -+
     -+test_expect_success 'setup' '
     -+	echo file0content >file0 &&
     -+	echo file1content >file1 &&
     -+	git add . &&
     -+	test_tick &&
     -+	git commit -m "initial commit" &&
     -+	git branch other-branch &&
     -+	echo file1main >file1 &&
     -+	git add . &&
     -+	test_tick &&
     -+	git commit -m "modify file1 on main" &&
     -+	git checkout other-branch &&
     -+	echo file1other >file1 &&
     -+	git add . &&
     -+	test_tick &&
     -+	git commit -m "modify file1 on other-branch" &&
     -+	echo file2content >file2 &&
     -+	git add . &&
     -+	test_tick &&
     -+	git commit -m "add file2 on other-branch" &&
     -+	git checkout main
     + ## t/t7201-co.sh ##
     +@@ t/t7201-co.sh: test_expect_success 'format of merge conflict from checkout -m' '
     + 	test_cmp expect current &&
     + 
     + 	cat <<-EOF >expect &&
     +-	<<<<<<< simple
     ++	<<<<<<< Updated upstream
     + 	a
     + 	c
     + 	e
     + 	=======
     + 	b
     + 	d
     +-	>>>>>>> local
     ++	>>>>>>> Stashed changes
     + 	EOF
     + 	test_cmp expect two
     + '
     +@@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
     + 	git checkout --merge --conflict=diff3 simple &&
     + 
     + 	cat <<-EOF >expect &&
     +-	<<<<<<< simple
     ++	<<<<<<< Updated upstream
     + 	a
     + 	c
     + 	e
     +-	||||||| main
     ++	||||||| Stash base
     + 	a
     + 	b
     + 	c
     +@@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
     + 	=======
     + 	b
     + 	d
     +-	>>>>>>> local
     ++	>>>>>>> Stashed changes
     + 	EOF
     + 	test_cmp expect two
     + '
     + 
     ++test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
     ++	git checkout -f main &&
     ++	git reset --hard &&
     ++	git clean -f &&
     ++
     ++	fill a b X d e >two &&
     ++	git checkout --merge --conflict=zdiff3 simple &&
     ++
     ++	cat <<-EOF >expect &&
     ++	a
     ++	<<<<<<< Updated upstream
     ++	c
     ++	||||||| Stash base
     ++	b
     ++	c
     ++	d
     ++	=======
     ++	b
     ++	X
     ++	d
     ++	>>>>>>> Stashed changes
     ++	e
     ++	EOF
     ++	test_cmp expect two
      +'
      +
     -+test_expect_success 'switch --autostash skips stash when no conflict' '
     -+	git branch branch1 other-branch &&
     -+	echo dirty >file0 &&
     -+	git switch --autostash branch1 >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	echo dirty >expected &&
     -+	test_cmp expected file0 &&
     -+	git switch main
     ++test_expect_success 'checkout -m respects merge.conflictStyle config' '
     ++	git checkout -f main &&
     ++	git reset --hard &&
     ++	git clean -f &&
     ++
     ++	test_config merge.conflictStyle diff3 &&
     ++	fill b d >two &&
     ++	git checkout -m simple &&
     ++
     ++	cat <<-EOF >expect &&
     ++	<<<<<<< Updated upstream
     ++	a
     ++	c
     ++	e
     ++	||||||| Stash base
     ++	a
     ++	b
     ++	c
     ++	d
     ++	e
     ++	=======
     ++	b
     ++	d
     ++	>>>>>>> Stashed changes
     ++	EOF
     ++	test_cmp expect two
      +'
      +
     -+test_expect_success 'checkout --autostash skips stash when no conflict' '
     -+	git branch branch2 other-branch &&
     -+	echo dirty >file0 &&
     -+	git checkout --autostash branch2 >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	echo dirty >expected &&
     -+	test_cmp expected file0 &&
     -+	git checkout main
     -+'
     ++test_expect_success 'checkout -m skips stash when no conflict' '
     ++	git checkout -f main &&
     ++	git clean -f &&
      +
     -+test_expect_success 'switch: checkout.autostash config skips stash when no conflict' '
     -+	git branch branch3 other-branch &&
     -+	echo dirty >file0 &&
     -+	test_config checkout.autostash true &&
     -+	git switch branch3 >actual 2>&1 &&
     ++	fill 0 x y z >same &&
     ++	git checkout -m side >actual 2>&1 &&
      +	test_grep ! "Created autostash" actual &&
     -+	echo dirty >expected &&
     -+	test_cmp expected file0 &&
     -+	git switch main
     ++	fill 0 x y z >expect &&
     ++	test_cmp expect same
      +'
      +
     -+test_expect_success 'checkout: checkout.autostash config skips stash when no conflict' '
     -+	git branch branch4 other-branch &&
     -+	echo dirty >file0 &&
     -+	test_config checkout.autostash true &&
     -+	git checkout branch4 >actual 2>&1 &&
     ++test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
     ++	git checkout -f main &&
     ++	git clean -f &&
     ++
     ++	fill 0 x y z >same &&
     ++	git add same &&
     ++	git checkout -m side >actual 2>&1 &&
      +	test_grep ! "Created autostash" actual &&
     -+	echo dirty >expected &&
     -+	test_cmp expected file0 &&
     -+	git checkout main
     ++	fill 0 x y z >expect &&
     ++	test_cmp expect same
      +'
      +
     -+test_expect_success '--no-autostash overrides checkout.autostash' '
     -+	git branch branch5 other-branch &&
     -+	echo dirty >file1 &&
     -+	test_config checkout.autostash true &&
     -+	test_must_fail git switch --no-autostash branch5 2>stderr &&
     -+	test_grep ! "Created autostash" stderr &&
     -+	git checkout -- file1
     -+'
     ++test_expect_success 'checkout -m stashes and applies on conflicting changes' '
     ++	git checkout -f main &&
     ++	git clean -f &&
      +
     -+test_expect_success '--autostash overrides checkout.autostash=false' '
     -+	git branch branch6 other-branch &&
     -+	echo dirty >file0 &&
     -+	test_config checkout.autostash false &&
     -+	git switch --autostash branch6 >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	echo dirty >expected &&
     -+	test_cmp expected file0 &&
     -+	git switch main
     ++	fill 1 2 3 4 5 6 7 >one &&
     ++	git checkout -m side >actual 2>&1 &&
     ++	test_grep "Created autostash" actual &&
     ++	test_grep "Applied autostash" actual &&
     ++	fill 1 2 3 4 5 6 7 >expect &&
     ++	test_cmp expect one
      +'
      +
     -+test_expect_success 'autostash with non-conflicting dirty index' '
     -+	git branch branch7 other-branch &&
     -+	echo dirty-index >file0 &&
     -+	git add file0 &&
     -+	git switch --autostash branch7 >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	echo dirty-index >expected &&
     -+	test_cmp expected file0 &&
     -+	git checkout -- file0 &&
     -+	git switch main
     ++test_expect_success 'checkout -m with mixed staged and unstaged changes' '
     ++	git checkout -f main &&
     ++	git clean -f &&
     ++
     ++	fill 0 x y z >same &&
     ++	git add same &&
     ++	fill 1 2 3 4 5 6 7 >one &&
     ++	git checkout -m side >actual 2>&1 &&
     ++	test_grep "Created autostash" actual &&
     ++	test_grep "Applied autostash" actual &&
     ++	fill 0 x y z >expect &&
     ++	test_cmp expect same &&
     ++	fill 1 2 3 4 5 6 7 >expect &&
     ++	test_cmp expect one
      +'
      +
     -+test_expect_success 'autostash bypasses conflicting local changes' '
     -+	git branch branch8 other-branch &&
     -+	echo dirty >file1 &&
     -+	test_must_fail git switch branch8 2>stderr &&
     ++test_expect_success 'checkout -m stashes on truly conflicting changes' '
     ++	git checkout -f main &&
     ++	git clean -f &&
     ++
     ++	fill 1 2 3 4 5 >one &&
     ++	test_must_fail git checkout side 2>stderr &&
      +	test_grep "Your local changes" stderr &&
     -+	git switch --autostash branch8 >actual 2>&1 &&
     ++	git checkout -m side >actual 2>&1 &&
      +	test_grep "Created autostash" actual &&
      +	test_grep "Applying autostash resulted in conflicts" actual &&
      +	test_grep "Your changes are safe in the stash" actual &&
      +	git stash drop &&
     -+	git reset --hard &&
     -+	git switch main
     ++	git reset --hard
      +'
      +
     -+test_expect_success 'autostash is a no-op with clean worktree' '
     -+	git branch branch9 other-branch &&
     -+	git switch --autostash branch9 >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	git switch main
     -+'
     -+
     -+test_expect_success '--autostash with --merge skips stash when no conflict' '
     -+	git branch branch10 other-branch &&
     -+	echo dirty >file0 &&
     -+	git switch --autostash --merge branch10 >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	echo dirty >expected &&
     -+	test_cmp expected file0 &&
     -+	git switch main
     -+'
     ++test_expect_success 'checkout -m produces usable stash on conflict' '
     ++	git checkout -f main &&
     ++	git clean -f &&
      +
     -+test_expect_success 'autostash with staged conflicting changes' '
     -+	git branch branch11 other-branch &&
     -+	echo staged-change >file1 &&
     -+	git add file1 &&
     -+	git switch --autostash branch11 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applying autostash resulted in conflicts" actual &&
     ++	fill 1 2 3 4 5 >one &&
     ++	git checkout -m side >actual 2>&1 &&
      +	test_grep "Your changes are safe in the stash" actual &&
     -+	git stash drop &&
     -+	git reset --hard &&
     -+	git switch main
     ++	git checkout -f main &&
     ++	git stash pop &&
     ++	fill 1 2 3 4 5 >expect &&
     ++	test_cmp expect one
      +'
      +
     -+test_expect_success '--autostash with --force preserves dirty changes' '
     -+	git branch branch12 other-branch &&
     -+	echo dirty-force >file1 &&
     -+	git switch --autostash --force branch12 >actual 2>&1 &&
     ++test_expect_success 'checkout -m stashes on staged conflicting changes' '
     ++	git checkout -f main &&
     ++	git clean -f &&
     ++
     ++	fill 1 2 3 4 5 >one &&
     ++	git add one &&
     ++	git checkout -m side >actual 2>&1 &&
      +	test_grep "Created autostash" actual &&
      +	test_grep "Applying autostash resulted in conflicts" actual &&
      +	test_grep "Your changes are safe in the stash" actual &&
      +	git stash drop &&
     -+	git reset --hard &&
     -+	git switch main
     ++	git reset --hard
      +'
      +
     -+test_expect_success '--autostash with new branch creation skips stash' '
     -+	echo dirty >file0 &&
     -+	git switch --autostash -c branch13 >actual 2>&1 &&
     ++test_expect_success 'checkout -m -b skips stash with dirty tree' '
     ++	git checkout -f main &&
     ++	git clean -f &&
     ++
     ++	fill 0 x y z >same &&
     ++	git checkout -m -b newbranch >actual 2>&1 &&
      +	test_grep ! "Created autostash" actual &&
     -+	echo dirty >expected &&
     -+	test_cmp expected file0 &&
     -+	git switch main &&
     -+	git branch -D branch13
     ++	fill 0 x y z >expect &&
     ++	test_cmp expect same &&
     ++	git checkout main &&
     ++	git branch -D newbranch
      +'
      +
     -+test_expect_success 'autostash with conflicting changes that apply cleanly' '
     -+	git branch branch14 other-branch &&
     -+	echo file1other >file1 &&
     -+	git switch --autostash branch14 >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     -+	echo file1other >expected &&
     -+	test_cmp expected file1 &&
     -+	git switch main
     -+'
     + test_expect_success 'switch to another branch while carrying a deletion' '
     + 	git checkout -f main &&
     + 	git reset --hard &&
     +
     + ## xdiff-interface.c ##
     +@@ xdiff-interface.c: int parse_conflict_style_name(const char *value)
     + 		return -1;
     + }
     + 
     ++const char *conflict_style_name(int style)
     ++{
     ++	switch (style) {
     ++	case XDL_MERGE_DIFF3:
     ++		return "diff3";
     ++	case XDL_MERGE_ZEALOUS_DIFF3:
     ++		return "zdiff3";
     ++	default:
     ++		return "merge";
     ++	}
     ++}
      +
     -+test_done
     + int git_xmerge_style = -1;
     + 
     + int git_xmerge_config(const char *var, const char *value,
      
     - ## t/t9902-completion.sh ##
     -@@ t/t9902-completion.sh: test_expect_success 'double dash "git checkout"' '
     - 	--ignore-other-worktrees Z
     - 	--recurse-submodules Z
     - 	--auto-advance Z
     -+	--autostash Z
     - 	--progress Z
     - 	--guess Z
     - 	--no-guess Z
     + ## xdiff-interface.h ##
     +@@ xdiff-interface.h: void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
     + void xdiff_clear_find_func(xdemitconf_t *xecfg);
     + struct config_context;
     + int parse_conflict_style_name(const char *value);
     ++const char *conflict_style_name(int style);
     + int git_xmerge_config(const char *var, const char *value,
     + 		      const struct config_context *ctx, void *cb);
     + extern int git_xmerge_style;


 Documentation/git-checkout.adoc |  50 +++++-----
 Documentation/git-switch.adoc   |  26 ++---
 builtin/checkout.c              | 160 +++++++++++++++---------------
 sequencer.c                     |   2 +-
 t/t7201-co.sh                   | 170 +++++++++++++++++++++++++++++++-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 7 files changed, 293 insertions(+), 128 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..1e8adf6ef3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,17 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list so you can use `git stash
+	pop` to recover and `git stash drop` when done.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +575,36 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would save the local
+changes in a stash entry and reset the working tree to allow switching:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Created autostash: 7a9afa3
+Applied autostash.
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the locally modified files overlap with files that need to be
+updated by the branch switch, the changes are stashed and reapplied
+after the switch.  If the stash application results in conflicts,
+they are not resolved and the stash is saved to the stash list:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
+Created autostash: 7a9afa3
+Applying autostash resulted in conflicts.
+Your changes are safe in the stash.
+You can run "git stash pop" or "git stash drop" at any time.
 ------------
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
-
-------------
-$ edit frotz
-$ git add frotz
-------------
+At this point, `git stash pop` can be used to recover and resolve
+the conflicts, and `git stash drop` to discard the stash when done.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..350e760fd2 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -126,15 +126,14 @@ variable.
 	If you have local modifications to one or more files that are
 	different between the current branch and the branch to which
 	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	order to preserve your modifications in context.  With this
+	option, the conflicting local changes are automatically
+	stashed before the switch and reapplied afterwards.  If the
+	local changes do not overlap with the differences between
+	branches, the switch proceeds without stashing.  If
+	reapplying the stash results in conflicts, the entry is
+	saved to the stash list so you can use `git stash pop` to
+	recover and `git stash drop` when done.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +216,16 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would save the local
+changes in a stash entry and reset the working tree to allow switching:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Created autostash: 7a9afa3
+Applied autostash.
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 1d1667fa4c..d3b3b815a7 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -845,83 +845,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
-		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
-		}
+		if (ret == -1)
+			return 1;
 	}
 
 	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
@@ -930,9 +855,6 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	if (write_locked_index(the_repository->index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
-	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
-		show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
-
 	return 0;
 }
 
@@ -1157,6 +1079,55 @@ static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
 	release_revisions(&revs);
 }
 
+static int checkout_would_clobber_changes(struct branch_info *old_branch_info,
+					  struct branch_info *new_branch_info)
+{
+	struct tree_desc trees[2];
+	struct tree *old_tree, *new_tree;
+	struct unpack_trees_options topts;
+	struct index_state tmp_index = INDEX_STATE_INIT(the_repository);
+	const struct object_id *old_commit_oid;
+	int ret;
+
+	if (!new_branch_info->commit)
+		return 0;
+
+	old_commit_oid = old_branch_info->commit ?
+		&old_branch_info->commit->object.oid :
+		the_hash_algo->empty_tree;
+	old_tree = repo_parse_tree_indirect(the_repository, old_commit_oid);
+	if (!old_tree)
+		return 0;
+
+	new_tree = repo_get_commit_tree(the_repository,
+					new_branch_info->commit);
+	if (!new_tree)
+		return 0;
+	if (repo_parse_tree(the_repository, new_tree) < 0)
+		return 0;
+
+	memset(&topts, 0, sizeof(topts));
+	topts.head_idx = -1;
+	topts.src_index = the_repository->index;
+	topts.dst_index = &tmp_index;
+	topts.initial_checkout = is_index_unborn(the_repository->index);
+	topts.merge = 1;
+	topts.update = 1;
+	topts.dry_run = 1;
+	topts.quiet = 1;
+	topts.fn = twoway_merge;
+
+	init_tree_desc(&trees[0], &old_tree->object.oid,
+		       old_tree->buffer, old_tree->size);
+	init_tree_desc(&trees[1], &new_tree->object.oid,
+		       new_tree->buffer, new_tree->size);
+
+	ret = unpack_trees(2, trees, &topts);
+	discard_index(&tmp_index);
+
+	return ret != 0;
+}
+
 static int switch_branches(const struct checkout_opts *opts,
 			   struct branch_info *new_branch_info)
 {
@@ -1202,9 +1173,19 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (opts->merge) {
+		if (repo_read_index(the_repository) < 0)
+			die(_("index file corrupt"));
+		if (checkout_would_clobber_changes(&old_branch_info,
+						   new_branch_info))
+			create_autostash_ref(the_repository,
+					     "CHECKOUT_AUTOSTASH");
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 		if (ret) {
+			apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
 			branch_info_release(&old_branch_info);
 			return ret;
 		}
@@ -1215,6 +1196,23 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
 
diff --git a/sequencer.c b/sequencer.c
index aafd0bc959..72f0afe609 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4677,7 +4677,7 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..9ace3962ba 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -171,14 +171,14 @@ test_expect_success 'format of merge conflict from checkout -m' '
 	test_cmp expect current &&
 
 	cat <<-EOF >expect &&
-	<<<<<<< simple
+	<<<<<<< Updated upstream
 	a
 	c
 	e
 	=======
 	b
 	d
-	>>>>>>> local
+	>>>>>>> Stashed changes
 	EOF
 	test_cmp expect two
 '
@@ -192,11 +192,11 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	git checkout --merge --conflict=diff3 simple &&
 
 	cat <<-EOF >expect &&
-	<<<<<<< simple
+	<<<<<<< Updated upstream
 	a
 	c
 	e
-	||||||| main
+	||||||| Stash base
 	a
 	b
 	c
@@ -205,11 +205,171 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	=======
 	b
 	d
-	>>>>>>> local
+	>>>>>>> Stashed changes
 	EOF
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< Updated upstream
+	c
+	||||||| Stash base
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> Stashed changes
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< Updated upstream
+	a
+	c
+	e
+	||||||| Stash base
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> Stashed changes
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "Created autostash" actual &&
+	test_grep "Applying autostash resulted in conflicts" actual &&
+	test_grep "Your changes are safe in the stash" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;

base-commit: 67006b9db8b772423ad0706029286096307d2567
-- 
gitgitgadget

Re: [PATCH v3] checkout: add --autostash option for branch switching

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> When switching branches, local modifications in the working tree can
> prevent the checkout from succeeding.  While "git rebase" and "git
> merge" already support --autostash to handle this case automatically,
> "git checkout" and "git switch" require users to manually stash and
> unstash their changes.
>
> Teach "git checkout" and "git switch" to accept --autostash and
> --no-autostash options that automatically create a temporary stash
> entry before the branch switch begins and apply it after the switch
> completes.  If the stash application results in conflicts, the stash
> entry is saved to the stash list so the user can resolve them later.
>
> Also add a checkout.autoStash configuration option that enables this
> behavior by default, which can be overridden with --no-autostash on
> the command line.
>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>     checkout: 'autostash' for branch switching

Almost all of the above is now stale, as we no longer call this the
"autostash" feature.  It turned into a project to vastly improve the
"checkout --merge" option, so the proposed log message needs to be
revamped to match.

Using the autostash mechanism to simplify checkout.c is a great
direction, I think, provided we can maintain the high-quality
conflict information (branch labels) that users expect from '-m'.

For a new iteration that invalidates almost everything from the
previous round, it is easier if range-diff were omitted from the
reviewers' point of view (I am not a GGG user, so I do not know if
there is such an option to do so).  It is not a huge deal as we can
simply ignore the large block of lines as irrelevant ;-)

>  Documentation/git-checkout.adoc |  50 +++++-----
>  Documentation/git-switch.adoc   |  26 ++---
>  builtin/checkout.c              | 160 +++++++++++++++---------------
>  sequencer.c                     |   2 +-
>  t/t7201-co.sh                   | 170 +++++++++++++++++++++++++++++++-
>  xdiff-interface.c               |  12 +++
>  xdiff-interface.h               |   1 +
>  7 files changed, 293 insertions(+), 128 deletions(-)
>
> diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
> index 43ccf47cf6..1e8adf6ef3 100644
> --- a/Documentation/git-checkout.adoc
> +++ b/Documentation/git-checkout.adoc
> @@ -251,20 +251,17 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
>  	are different between the current branch and the branch to
>  	which you are switching, the command refuses to switch
>  	branches in order to preserve your modifications in context.
> +	With this option, the conflicting local changes are
> +	automatically stashed before the switch and reapplied
> +	afterwards.  If the local changes do not overlap with the
> +	differences between branches, the switch proceeds without
> +	stashing.  If reapplying the stash results in conflicts, the
> +	entry is saved to the stash list so you can use `git stash
> +	pop` to recover and `git stash drop` when done.

Great.

> -+
> -When switching branches with `--merge`, staged changes may be lost.

Hmph, I have to admit that I never do "checkout" to go to a different
branch with a dirty index that does not match the current HEAD, with
or without "--merge"; in fact, not just "I never do" myself, I never
thought about what happens when somebody does so, so I do not offhand
know what the current code without this patch does, or what the updated
code would.  In "stash && switch && unstash" flow, the last "unstash"
is what decides if the original changes in the index is reapplied to
the index or not, IIRC, so we still may lose the distinction between
what has been and what has not been added to the index after all,
depending on the way how the new code does the "unstash" step.

> @@ -578,39 +575,36 @@ $ git checkout mytopic
>  error: You have local changes to 'frotz'; not switching branches.
>  ------------
>  
> -You can give the `-m` flag to the command, which would try a
> -three-way merge:
> +You can give the `-m` flag to the command, which would save the local
> +changes in a stash entry and reset the working tree to allow switching:
>  
>  ------------
>  $ git checkout -m mytopic
> -Auto-merging frotz
> +Created autostash: 7a9afa3
> +Applied autostash.
>  ------------
>  
> -After this three-way merge, the local modifications are _not_
> +After the switch, the local modifications are reapplied and are _not_
>  registered in your index file, so `git diff` would show you what
>  changes you made since the tip of the new branch.

OK.

>  === 3. Merge conflict
>  
> -When a merge conflict happens during switching branches with
> -the `-m` option, you would see something like this:
> +When the locally modified files overlap with files that need to be
> +updated by the branch switch, the changes are stashed and reapplied
> +after the switch.  If the stash application results in conflicts,

In the original text of this third example (and as I understand,
these examples are written to be read more-or-less independently),
the `-m` option was explicitly mentioned to make it clear that this
"conflict" situation is relevant only when the option is used.  In
the updated text, it is not.  We should mention `-m` somewhere in
the updated text as well: When the `--merge` (`-m`) option is in
effect, _this_ happens.

> +they are not resolved and the stash is saved to the stash list:
>  
>  ------------
>  $ git checkout -m mytopic
> -Auto-merging frotz
> -ERROR: Merge conflict in frotz
> -fatal: merge program failed
> +Created autostash: 7a9afa3
> +Applying autostash resulted in conflicts.
> +Your changes are safe in the stash.
> +You can run "git stash pop" or "git stash drop" at any time.
>  ------------

Nice.  It may probably be on a bit too verbose side, though.  The
fact we are creating a stash entry or the object name of it is not
interesting to the user unless there is a conflict, so I would have
thought we would not say "Created autostash" at all, and the last
three lines would be replaced with something like the following
and shown _only_ when the application of the stashed changes did not
succeed cleanly:

    Your local changes are stashed, however, applying it to carry
    forward your local changes resulted in conflicts:

     - You can try resolving them now.  If you resolved them
       successfully, discard the stash entry with "git stash drop".

     - Alternatively you can "git reset --hard" if you do not want
       to deal with them right now, and later "git stash pop" to
       recover your local changes.

> -At this point, `git diff` shows the changes cleanly merged as in
> -the previous example, as well as the changes in the conflicted
> -files.  Edit and resolve the conflict and mark it resolved with
> -`git add` as usual:
> -
> -------------
> -$ edit frotz
> -$ git add frotz
> -------------

After resolving and adding, they need to do "git stash drop" it, but
other than that, this part of the example is still valid, isn't it?

The improvement this patch brings in is that the user now has
another choice, i.e.,

    Instead of editing and resolving the conflicts right now, you
    can clear the slate with `git reset --hard` and resurrect the
    local changes, safely stored in the stash at your leisure, with
    `git stash pop`.

> +At this point, `git stash pop` can be used to recover and resolve
> +the conflicts, and `git stash drop` to discard the stash when done.

This is not giving a wrong instruction per-se, but my suggestion
above can be used to extend it if we wanted to.  It may make it
easier to understand to the readers, or it may make it way too
verbose.  I dunno.

> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index 1d1667fa4c..d3b3b815a7 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -17,7 +17,6 @@
>  #include "merge-ll.h"
>  #include "lockfile.h"
>  #include "mem-pool.h"
> -#include "merge-ort-wrappers.h"
>  #include "object-file.h"
>  #include "object-name.h"
>  #include "odb.h"
> @@ -30,6 +29,7 @@
>  #include "repo-settings.h"
>  #include "resolve-undo.h"
>  #include "revision.h"
> +#include "sequencer.h"
>  #include "setup.h"
>  #include "submodule.h"
>  #include "symlinks.h"
> @@ -845,83 +845,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
>  
>  		ret = unpack_trees(2, trees, &topts);
>  		clear_unpack_trees_porcelain(&topts);
> -		if (ret == -1) {
> -			/*
> -			 * Unpack couldn't do a trivial merge; either
> -			 * give up or do a real merge, depending on
> -			 * whether the merge flag was used.
> -			 */
> -...
> -		}
> +		if (ret == -1)
> +			return 1;
>  	}

So pleased to see so much custom code getting removed ;-).

> diff --git a/sequencer.c b/sequencer.c
> index aafd0bc959..72f0afe609 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4677,7 +4677,7 @@ static void create_autostash_internal(struct repository *r,
>  					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
>  		}
>  
> -		printf(_("Created autostash: %s\n"), buf.buf);
> +		fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
>  		if (reset_head(r, &ropts) < 0)
>  			die(_("could not reset --hard"));
>  		discard_index(r->index);

Is this change something all the callers that passes control through
this part desire?  Don't some of them want the output go to the
standard output, not standard error?

If we are going in the direction I suggested above (i.e., be silent
about our use of stashes before it becomes relevant to the user),
this part may have to become a conditional

	if (!silent)
		printf(_("Created autostash: %s\n"), buf.buf);

or something, where all the current callers before the "checkout
--merge" adds a new caller would pass silent==0 to.

Whatever changes this function needs, it looks more like a separate
preparatory patch to me.

> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..9ace3962ba 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -171,14 +171,14 @@ test_expect_success 'format of merge conflict from checkout -m' '
>  	test_cmp expect current &&
>  
>  	cat <<-EOF >expect &&
> -	<<<<<<< simple
> +	<<<<<<< Updated upstream
>  	a
>  	c
>  	e
>  	=======
>  	b
>  	d
> -	>>>>>>> local
> +	>>>>>>> Stashed changes
>  	EOF
>  	test_cmp expect two
>  '

Historically, 'git checkout -m' provided the branch names (e.g.,
"<<<<<<< simple"), which is very helpful context.  It would be great
if we could find a way to pass the branch names through as labels to
the stash application.  It may require a preparatory change to "git
stash apply" to allow customizing the labels---the underlying
machinery at the lowest level does have ability to use labels the
callers want it to use, so it may be just the matter of plumbing it
through the callchain.  I didn't check.

> diff --git a/xdiff-interface.c b/xdiff-interface.c
> index f043330f2a..5ee2b96d0a 100644
> --- a/xdiff-interface.c
> +++ b/xdiff-interface.c
> @@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
>  		return -1;
>  }
>  
> +const char *conflict_style_name(int style)
> +{
> +	switch (style) {
> +	case XDL_MERGE_DIFF3:
> +		return "diff3";
> +	case XDL_MERGE_ZEALOUS_DIFF3:
> +		return "zdiff3";
> +	default:
> +		return "merge";
> +	}
> +}
> +
>  int git_xmerge_style = -1;
>  
>  int git_xmerge_config(const char *var, const char *value,
> diff --git a/xdiff-interface.h b/xdiff-interface.h
> index fbc4ceec40..ce54e1c0e0 100644
> --- a/xdiff-interface.h
> +++ b/xdiff-interface.h
> @@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
>  void xdiff_clear_find_func(xdemitconf_t *xecfg);
>  struct config_context;
>  int parse_conflict_style_name(const char *value);
> +const char *conflict_style_name(int style);
>  int git_xmerge_config(const char *var, const char *value,
>  		      const struct config_context *ctx, void *cb);
>  extern int git_xmerge_style;

This may be a useful addition, but it would probably need to become
a separate preparatory patch, possibly with its own test.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Almost all of the above is now stale, as we no longer call this the
> "autostash" feature.  It turned into a project to vastly improve the
> "checkout --merge" option, so the proposed log message needs to be
> revamped to match.

My feeling is that this feature will drift far away from what I initially
needed. I have never used 'checkout -m' but stash->checkout-unstash is a
pattern I use a lot.

I wonder with how complicated this might turn out, if it would be better to
have this as a separate feature called autostash (mirroring the same
feature from git pull rebase which I have enabled).

Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Harald Nordgren <haraldnordgren@gmail.com> writes:

>> Almost all of the above is now stale, as we no longer call this the
>> "autostash" feature.  It turned into a project to vastly improve the
>> "checkout --merge" option, so the proposed log message needs to be
>> revamped to match.
>
> My feeling is that this feature will drift far away from what I initially
> needed. I have never used 'checkout -m' but stash->checkout-unstash is a
> pattern I use a lot.

Perhaps.  But things like "checkout --autostash", which can entirely
be done by the end user via a wrapper script or an alias, is not
interesting enough from my point of view.

[PATCH v4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: 'autostash' for branch switching
    
    cc: Phillip Wood phillip.wood123@gmail.com

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v4
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v3:

 1:  05f1e53163 ! 1:  5d49c0031a checkout: add --autostash option for branch switching
     @@ Metadata
      Author: Harald Nordgren <haraldnordgren@gmail.com>
      
       ## Commit message ##
     -    checkout: add --autostash option for branch switching
     +    checkout: -m (--merge) uses autostash when switching branches
      
     -    When switching branches, local modifications in the working tree can
     -    prevent the checkout from succeeding.  While "git rebase" and "git
     -    merge" already support --autostash to handle this case automatically,
     -    "git checkout" and "git switch" require users to manually stash and
     -    unstash their changes.
     -
     -    Teach "git checkout" and "git switch" to accept --autostash and
     -    --no-autostash options that automatically create a temporary stash
     -    entry before the branch switch begins and apply it after the switch
     -    completes.  If the stash application results in conflicts, the stash
     -    entry is saved to the stash list so the user can resolve them later.
     -
     -    Also add a checkout.autoStash configuration option that enables this
     -    behavior by default, which can be overridden with --no-autostash on
     -    the command line.
     +    When switching branches with "git checkout -m", local modifications
     +    can block the switch.  Teach the -m flow to create a temporary stash
     +    before switching and reapply it after.  On success, only "Applied
     +    autostash." is shown.  If reapplying causes conflicts, the stash is
     +    kept and the user is told they can resolve and run "git stash drop",
     +    or run "git reset --hard" and later "git stash pop" to recover their
     +    changes.
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
       ------------
       $ git checkout -m mytopic
      -Auto-merging frotz
     -+Created autostash: 7a9afa3
      +Applied autostash.
       ------------
       
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
       
      -When a merge conflict happens during switching branches with
      -the `-m` option, you would see something like this:
     -+When the locally modified files overlap with files that need to be
     -+updated by the branch switch, the changes are stashed and reapplied
     -+after the switch.  If the stash application results in conflicts,
     -+they are not resolved and the stash is saved to the stash list:
     ++When the `--merge` (`-m`) option is in effect and the locally
     ++modified files overlap with files that need to be updated by the
     ++branch switch, the changes are stashed and reapplied after the
     ++switch.  If the stash application results in conflicts, they are not
     ++resolved and the stash is saved to the stash list:
       
       ------------
       $ git checkout -m mytopic
      -Auto-merging frotz
      -ERROR: Merge conflict in frotz
      -fatal: merge program failed
     -+Created autostash: 7a9afa3
     -+Applying autostash resulted in conflicts.
     -+Your changes are safe in the stash.
     -+You can run "git stash pop" or "git stash drop" at any time.
     - ------------
     +-------------
     ++Your local changes are stashed, however, applying it to carry
     ++forward your local changes resulted in conflicts:
       
      -At this point, `git diff` shows the changes cleanly merged as in
      -the previous example, as well as the changes in the conflicted
      -files.  Edit and resolve the conflict and mark it resolved with
      -`git add` as usual:
     --
     --------------
     ++ - You can try resolving them now.  If you resolved them
     ++   successfully, discard the stash entry with "git stash drop".
     + 
     ++ - Alternatively you can "git reset --hard" if you do not want
     ++   to deal with them right now, and later "git stash pop" to
     ++   recover your local changes.
     + ------------
      -$ edit frotz
      -$ git add frotz
      -------------
     -+At this point, `git stash pop` can be used to recover and resolve
     -+the conflicts, and `git stash drop` to discard the stash when done.
     ++
     ++You can try resolving the conflicts now.  Edit the conflicting files
     ++and mark them resolved with `git add` as usual, then run `git stash
     ++drop` to discard the stash entry.  Alternatively, you can clear the
     ++working tree with `git reset --hard` and recover your local changes
     ++later with `git stash pop`.
       
       CONFIGURATION
       -------------
     @@ builtin/checkout.c: static void orphaned_commit_warning(struct commit *old_commi
       static int switch_branches(const struct checkout_opts *opts,
       			   struct branch_info *new_branch_info)
       {
     +@@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
     + 	struct object_id rev;
     + 	int flag, writeout_error = 0;
     + 	int do_merge = 1;
     ++	struct strbuf old_commit_shortname = STRBUF_INIT;
     ++	const char *stash_label_ancestor = NULL;
     + 
     + 	trace2_cmd_mode("branch");
     + 
      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       			do_merge = 0;
       	}
       
     ++	if (old_branch_info.name)
     ++		stash_label_ancestor = old_branch_info.name;
     ++	else if (old_branch_info.commit) {
     ++		strbuf_add_unique_abbrev(&old_commit_shortname,
     ++					 &old_branch_info.commit->object.oid,
     ++					 DEFAULT_ABBREV);
     ++		stash_label_ancestor = old_commit_shortname.buf;
     ++	}
     ++
      +	if (opts->merge) {
      +		if (repo_read_index(the_repository) < 0)
      +			die(_("index file corrupt"));
      +		if (checkout_would_clobber_changes(&old_branch_info,
      +						   new_branch_info))
     -+			create_autostash_ref(the_repository,
     -+					     "CHECKOUT_AUTOSTASH");
     ++			create_autostash_ref_silent(the_repository,
     ++						   "CHECKOUT_AUTOSTASH");
      +	}
      +
       	if (do_merge) {
       		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
       		if (ret) {
     -+			apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
     ++			apply_autostash_ref_with_labels(the_repository,
     ++						       "CHECKOUT_AUTOSTASH",
     ++						       new_branch_info->name,
     ++						       "local",
     ++						       stash_label_ancestor);
       			branch_info_release(&old_branch_info);
     ++			strbuf_release(&old_commit_shortname);
       			return ret;
       		}
     + 	}
      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       
       	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +		git_config_push_parameter(cfg.buf);
      +		strbuf_release(&cfg);
      +	}
     -+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH");
     ++	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
     ++				       new_branch_info->name, "local",
     ++				       stash_label_ancestor);
      +
      +	discard_index(the_repository->index);
      +	if (repo_read_index(the_repository) < 0)
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +
       	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
       	branch_info_release(&old_branch_info);
     ++	strbuf_release(&old_commit_shortname);
     + 
     + 	return ret || writeout_error;
     + }
     +
     + ## builtin/stash.c ##
     +@@ builtin/stash.c: static void unstage_changes_unless_new(struct object_id *orig_tree)
     + 		die(_("could not write index"));
     + }
     + 
     +-static int do_apply_stash(const char *prefix, struct stash_info *info,
     +-			  int index, int quiet)
     ++static int do_apply_stash_with_labels(const char *prefix,
     ++				      struct stash_info *info,
     ++				      int index, int quiet,
     ++				      const char *label1, const char *label2,
     ++				      const char *label_ancestor)
     + {
     + 	int clean, ret;
     + 	int has_index = index;
     +@@ builtin/stash.c: static int do_apply_stash(const char *prefix, struct stash_info *info,
       
     + 	init_ui_merge_options(&o, the_repository);
     + 
     +-	o.branch1 = "Updated upstream";
     +-	o.branch2 = "Stashed changes";
     +-	o.ancestor = "Stash base";
     ++	o.branch1 = label1 ? label1 : "Updated upstream";
     ++	o.branch2 = label2 ? label2 : "Stashed changes";
     ++	o.ancestor = label_ancestor ? label_ancestor : "Stash base";
     + 
     + 	if (oideq(&info->b_tree, &c_tree))
     + 		o.branch1 = "Version stash was based on";
     +@@ builtin/stash.c: restore_untracked:
     + 	return ret;
     + }
     + 
     ++static int do_apply_stash(const char *prefix, struct stash_info *info,
     ++			  int index, int quiet)
     ++{
     ++	return do_apply_stash_with_labels(prefix, info, index, quiet,
     ++					  NULL, NULL, NULL);
     ++}
     ++
     + static int apply_stash(int argc, const char **argv, const char *prefix,
     + 		       struct repository *repo UNUSED)
     + {
     + 	int ret = -1;
     + 	int quiet = 0;
     + 	int index = use_index;
     ++	const char *label1 = NULL, *label2 = NULL, *label_ancestor = NULL;
     + 	struct stash_info info = STASH_INFO_INIT;
     + 	struct option options[] = {
     + 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
     + 		OPT_BOOL(0, "index", &index,
     + 			 N_("attempt to recreate the index")),
     ++		OPT_STRING(0, "ours-label", &label1, N_("label"),
     ++			   N_("label for the upstream side in conflict markers")),
     ++		OPT_STRING(0, "theirs-label", &label2, N_("label"),
     ++			   N_("label for the stashed side in conflict markers")),
     ++		OPT_STRING(0, "base-label", &label_ancestor, N_("label"),
     ++			   N_("label for the base in diff3 conflict markers")),
     + 		OPT_END()
     + 	};
     + 
     +@@ builtin/stash.c: static int apply_stash(int argc, const char **argv, const char *prefix,
     + 	if (get_stash_info(&info, argc, argv))
     + 		goto cleanup;
     + 
     +-	ret = do_apply_stash(prefix, &info, index, quiet);
     ++	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
     ++					 label1, label2, label_ancestor);
     + cleanup:
     + 	free_stash_info(&info);
     + 	return ret;
      
       ## sequencer.c ##
     +@@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list, int offset)
     + 
     + static void create_autostash_internal(struct repository *r,
     + 				      const char *path,
     +-				      const char *refname)
     ++				      const char *refname,
     ++				      int silent)
     + {
     + 	struct strbuf buf = STRBUF_INIT;
     + 	struct lock_file lock_file = LOCK_INIT;
      @@ sequencer.c: static void create_autostash_internal(struct repository *r,
       					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
       		}
       
      -		printf(_("Created autostash: %s\n"), buf.buf);
     -+		fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
     ++		if (!silent)
     ++			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
       		if (reset_head(r, &ropts) < 0)
       			die(_("could not reset --hard"));
       		discard_index(r->index);
     +@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     + 
     + void create_autostash(struct repository *r, const char *path)
     + {
     +-	create_autostash_internal(r, path, NULL);
     ++	create_autostash_internal(r, path, NULL, 0);
     + }
     + 
     + void create_autostash_ref(struct repository *r, const char *refname)
     + {
     +-	create_autostash_internal(r, NULL, refname);
     ++	create_autostash_internal(r, NULL, refname, 0);
     + }
     + 
     +-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     ++void create_autostash_ref_silent(struct repository *r, const char *refname)
     ++{
     ++	create_autostash_internal(r, NULL, refname, 1);
     ++}
     ++
     ++static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
     ++				    const char *label1, const char *label2,
     ++				    const char *label_ancestor)
     + {
     + 	struct child_process child = CHILD_PROCESS_INIT;
     + 	int ret = 0;
     +@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     + 		child.no_stderr = 1;
     + 		strvec_push(&child.args, "stash");
     + 		strvec_push(&child.args, "apply");
     ++		if (label1)
     ++			strvec_pushf(&child.args, "--ours-label=%s", label1);
     ++		if (label2)
     ++			strvec_pushf(&child.args, "--theirs-label=%s", label2);
     ++		if (label_ancestor)
     ++			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);
     + 		strvec_push(&child.args, stash_oid);
     + 		ret = run_command(&child);
     + 	}
     +@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     + 		strvec_push(&store.args, stash_oid);
     + 		if (run_command(&store))
     + 			ret = error(_("cannot store %s"), stash_oid);
     ++		else if (attempt_apply)
     ++			fprintf(stderr,
     ++				_("Your local changes are stashed, however, applying it to carry\n"
     ++				  "forward your local changes resulted in conflicts:\n"
     ++				  "\n"
     ++				  " - You can try resolving them now.  If you resolved them\n"
     ++				  "   successfully, discard the stash entry with \"git stash drop\".\n"
     ++				  "\n"
     ++				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
     ++				  "   to deal with them right now, and later \"git stash pop\" to\n"
     ++				  "   recover your local changes.\n"));
     + 		else
     + 			fprintf(stderr,
     +-				_("%s\n"
     ++				_("Autostash exists; creating a new stash entry.\n"
     + 				  "Your changes are safe in the stash.\n"
     + 				  "You can run \"git stash pop\" or"
     +-				  " \"git stash drop\" at any time.\n"),
     +-				attempt_apply ?
     +-				_("Applying autostash resulted in conflicts.") :
     +-				_("Autostash exists; creating a new stash entry."));
     ++				  " \"git stash drop\" at any time.\n"));
     + 	}
     + 
     + 	return ret;
     +@@ sequencer.c: static int apply_save_autostash(const char *path, int attempt_apply)
     + 	}
     + 	strbuf_trim(&stash_oid);
     + 
     +-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
     ++	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
     ++				      NULL, NULL, NULL);
     + 
     + 	unlink(path);
     + 	strbuf_release(&stash_oid);
     +@@ sequencer.c: int apply_autostash(const char *path)
     + 
     + int apply_autostash_oid(const char *stash_oid)
     + {
     +-	return apply_save_autostash_oid(stash_oid, 1);
     ++	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
     + }
     + 
     + static int apply_save_autostash_ref(struct repository *r, const char *refname,
     +-				    int attempt_apply)
     ++				    int attempt_apply,
     ++				    const char *label1, const char *label2,
     ++				    const char *label_ancestor)
     + {
     + 	struct object_id stash_oid;
     + 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
     +@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     + 		return error(_("autostash reference is a symref"));
     + 
     + 	oid_to_hex_r(stash_oid_hex, &stash_oid);
     +-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
     ++	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
     ++				       label1, label2, label_ancestor);
     + 
     + 	refs_delete_ref(get_main_ref_store(r), "", refname,
     + 			&stash_oid, REF_NO_DEREF);
     +@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     + 
     + int save_autostash_ref(struct repository *r, const char *refname)
     + {
     +-	return apply_save_autostash_ref(r, refname, 0);
     ++	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
     + }
     + 
     + int apply_autostash_ref(struct repository *r, const char *refname)
     + {
     +-	return apply_save_autostash_ref(r, refname, 1);
     ++	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
     ++}
     ++
     ++int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     ++				    const char *label1, const char *label2,
     ++				    const char *label_ancestor)
     ++{
     ++	return apply_save_autostash_ref(r, refname, 1,
     ++					label1, label2, label_ancestor);
     + }
     + 
     + static int checkout_onto(struct repository *r, struct replay_opts *opts,
      
     - ## t/t7201-co.sh ##
     -@@ t/t7201-co.sh: test_expect_success 'format of merge conflict from checkout -m' '
     - 	test_cmp expect current &&
     - 
     - 	cat <<-EOF >expect &&
     --	<<<<<<< simple
     -+	<<<<<<< Updated upstream
     - 	a
     - 	c
     - 	e
     - 	=======
     - 	b
     - 	d
     --	>>>>>>> local
     -+	>>>>>>> Stashed changes
     + ## sequencer.h ##
     +@@ sequencer.h: void commit_post_rewrite(struct repository *r,
     + 
     + void create_autostash(struct repository *r, const char *path);
     + void create_autostash_ref(struct repository *r, const char *refname);
     ++void create_autostash_ref_silent(struct repository *r, const char *refname);
     + int save_autostash(const char *path);
     + int save_autostash_ref(struct repository *r, const char *refname);
     + int apply_autostash(const char *path);
     + int apply_autostash_oid(const char *stash_oid);
     + int apply_autostash_ref(struct repository *r, const char *refname);
     ++int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     ++				    const char *label1, const char *label2,
     ++				    const char *label_ancestor);
     + 
     + #define SUMMARY_INITIAL_COMMIT   (1 << 0)
     + #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
     +
     + ## t/t3420-rebase-autostash.sh ##
     +@@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {
     + 	First, rewinding head to replay your work on top of it...
     + 	Applying: second commit
     + 	Applying: third commit
     +-	Applying autostash resulted in conflicts.
     +-	Your changes are safe in the stash.
     +-	You can run "git stash pop" or "git stash drop" at any time.
     ++	Your local changes are stashed, however, applying it to carry
     ++	forward your local changes resulted in conflicts:
     ++
     ++	 - You can try resolving them now.  If you resolved them
     ++	   successfully, discard the stash entry with "git stash drop".
     ++
     ++	 - Alternatively you can "git reset --hard" if you do not want
     ++	   to deal with them right now, and later "git stash pop" to
     ++	   recover your local changes.
       	EOF
     - 	test_cmp expect two
     - '
     -@@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
     - 	git checkout --merge --conflict=diff3 simple &&
     - 
     - 	cat <<-EOF >expect &&
     --	<<<<<<< simple
     -+	<<<<<<< Updated upstream
     - 	a
     - 	c
     - 	e
     --	||||||| main
     -+	||||||| Stash base
     - 	a
     - 	b
     - 	c
     -@@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
     - 	=======
     - 	b
     - 	d
     --	>>>>>>> local
     -+	>>>>>>> Stashed changes
     + }
     + 
     + create_expected_failure_merge () {
     + 	cat >expected <<-EOF
     + 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
     +-	Applying autostash resulted in conflicts.
     +-	Your changes are safe in the stash.
     +-	You can run "git stash pop" or "git stash drop" at any time.
     ++	Your local changes are stashed, however, applying it to carry
     ++	forward your local changes resulted in conflicts:
     ++
     ++	 - You can try resolving them now.  If you resolved them
     ++	   successfully, discard the stash entry with "git stash drop".
     ++
     ++	 - Alternatively you can "git reset --hard" if you do not want
     ++	   to deal with them right now, and later "git stash pop" to
     ++	   recover your local changes.
     + 	Successfully rebased and updated refs/heads/rebased-feature-branch.
       	EOF
     + }
     +
     + ## t/t7201-co.sh ##
     +@@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
       	test_cmp expect two
       '
       
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +
      +	cat <<-EOF >expect &&
      +	a
     -+	<<<<<<< Updated upstream
     ++	<<<<<<< simple
      +	c
     -+	||||||| Stash base
     ++	||||||| main
      +	b
      +	c
      +	d
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	b
      +	X
      +	d
     -+	>>>>>>> Stashed changes
     ++	>>>>>>> local
      +	e
      +	EOF
      +	test_cmp expect two
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	git checkout -m simple &&
      +
      +	cat <<-EOF >expect &&
     -+	<<<<<<< Updated upstream
     ++	<<<<<<< simple
      +	a
      +	c
      +	e
     -+	||||||| Stash base
     ++	||||||| main
      +	a
      +	b
      +	c
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	=======
      +	b
      +	d
     -+	>>>>>>> Stashed changes
     ++	>>>>>>> local
      +	EOF
      +	test_cmp expect two
      +'
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +
      +	fill 1 2 3 4 5 6 7 >one &&
      +	git checkout -m side >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	test_grep "Applied autostash" actual &&
      +	fill 1 2 3 4 5 6 7 >expect &&
      +	test_cmp expect one
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	git add same &&
      +	fill 1 2 3 4 5 6 7 >one &&
      +	git checkout -m side >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     ++	test_grep ! "Created autostash" actual &&
      +	test_grep "Applied autostash" actual &&
      +	fill 0 x y z >expect &&
      +	test_cmp expect same &&
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	test_must_fail git checkout side 2>stderr &&
      +	test_grep "Your local changes" stderr &&
      +	git checkout -m side >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applying autostash resulted in conflicts" actual &&
     -+	test_grep "Your changes are safe in the stash" actual &&
     ++	test_grep ! "Created autostash" actual &&
     ++	test_grep "resulted in conflicts" actual &&
     ++	test_grep "git stash drop" actual &&
      +	git stash drop &&
      +	git reset --hard
      +'
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +
      +	fill 1 2 3 4 5 >one &&
      +	git checkout -m side >actual 2>&1 &&
     -+	test_grep "Your changes are safe in the stash" actual &&
     ++	test_grep "recover your local changes" actual &&
      +	git checkout -f main &&
      +	git stash pop &&
      +	fill 1 2 3 4 5 >expect &&
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	fill 1 2 3 4 5 >one &&
      +	git add one &&
      +	git checkout -m side >actual 2>&1 &&
     -+	test_grep "Created autostash" actual &&
     -+	test_grep "Applying autostash resulted in conflicts" actual &&
     -+	test_grep "Your changes are safe in the stash" actual &&
     ++	test_grep ! "Created autostash" actual &&
     ++	test_grep "resulted in conflicts" actual &&
     ++	test_grep "git stash drop" actual &&
      +	git stash drop &&
      +	git reset --hard
      +'
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
       	git checkout -f main &&
       	git reset --hard &&
      
     + ## t/t7600-merge.sh ##
     +@@ t/t7600-merge.sh: test_expect_success 'merge --squash --autostash conflict does not attempt to app
     + 	>unrelated &&
     + 	git add unrelated &&
     + 	test_must_fail git merge --squash c7 --autostash >out 2>err &&
     +-	! grep "Applying autostash resulted in conflicts." err &&
     ++	! grep "resulted in conflicts" err &&
     + 	grep "When finished, apply stashed changes with \`git stash pop\`" out
     + '
     + 
     +@@ t/t7600-merge.sh: test_expect_success 'merge with conflicted --autostash changes' '
     + 	git diff >expect &&
     + 	test_when_finished "test_might_fail git stash drop" &&
     + 	git merge --autostash c3 2>err &&
     +-	test_grep "Applying autostash resulted in conflicts." err &&
     ++	test_grep "resulted in conflicts" err &&
     + 	git show HEAD:file >merge-result &&
     + 	test_cmp result.1-9 merge-result &&
     + 	git stash show -p >actual &&
     +
       ## xdiff-interface.c ##
      @@ xdiff-interface.c: int parse_conflict_style_name(const char *value)
       		return -1;


 Documentation/git-checkout.adoc |  56 +++++-----
 Documentation/git-switch.adoc   |  26 ++---
 builtin/checkout.c              | 179 +++++++++++++++++---------------
 builtin/stash.c                 |  30 ++++--
 sequencer.c                     |  67 +++++++++---
 sequencer.h                     |   4 +
 t/t3420-rebase-autostash.sh     |  24 +++--
 t/t7201-co.sh                   | 160 ++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   4 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 11 files changed, 412 insertions(+), 151 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..9d5f5c51ae 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,17 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list so you can use `git stash
+	pop` to recover and `git stash drop` when done.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +575,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would save the local
+changes in a stash entry and reset the working tree to allow switching:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Applied autostash.
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If the stash application results in conflicts, they are not
+resolved and the stash is saved to the stash list:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..350e760fd2 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -126,15 +126,14 @@ variable.
 	If you have local modifications to one or more files that are
 	different between the current branch and the branch to which
 	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	order to preserve your modifications in context.  With this
+	option, the conflicting local changes are automatically
+	stashed before the switch and reapplied afterwards.  If the
+	local changes do not overlap with the differences between
+	branches, the switch proceeds without stashing.  If
+	reapplying the stash results in conflicts, the entry is
+	saved to the stash list so you can use `git stash pop` to
+	recover and `git stash drop` when done.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +216,16 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would save the local
+changes in a stash entry and reset the working tree to allow switching:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Created autostash: 7a9afa3
+Applied autostash.
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 1d1667fa4c..1968e46ae9 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -845,83 +845,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
-		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
-		}
+		if (ret == -1)
+			return 1;
 	}
 
 	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
@@ -930,9 +855,6 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	if (write_locked_index(the_repository->index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
-	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
-		show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
-
 	return 0;
 }
 
@@ -1157,6 +1079,55 @@ static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
 	release_revisions(&revs);
 }
 
+static int checkout_would_clobber_changes(struct branch_info *old_branch_info,
+					  struct branch_info *new_branch_info)
+{
+	struct tree_desc trees[2];
+	struct tree *old_tree, *new_tree;
+	struct unpack_trees_options topts;
+	struct index_state tmp_index = INDEX_STATE_INIT(the_repository);
+	const struct object_id *old_commit_oid;
+	int ret;
+
+	if (!new_branch_info->commit)
+		return 0;
+
+	old_commit_oid = old_branch_info->commit ?
+		&old_branch_info->commit->object.oid :
+		the_hash_algo->empty_tree;
+	old_tree = repo_parse_tree_indirect(the_repository, old_commit_oid);
+	if (!old_tree)
+		return 0;
+
+	new_tree = repo_get_commit_tree(the_repository,
+					new_branch_info->commit);
+	if (!new_tree)
+		return 0;
+	if (repo_parse_tree(the_repository, new_tree) < 0)
+		return 0;
+
+	memset(&topts, 0, sizeof(topts));
+	topts.head_idx = -1;
+	topts.src_index = the_repository->index;
+	topts.dst_index = &tmp_index;
+	topts.initial_checkout = is_index_unborn(the_repository->index);
+	topts.merge = 1;
+	topts.update = 1;
+	topts.dry_run = 1;
+	topts.quiet = 1;
+	topts.fn = twoway_merge;
+
+	init_tree_desc(&trees[0], &old_tree->object.oid,
+		       old_tree->buffer, old_tree->size);
+	init_tree_desc(&trees[1], &new_tree->object.oid,
+		       new_tree->buffer, new_tree->size);
+
+	ret = unpack_trees(2, trees, &topts);
+	discard_index(&tmp_index);
+
+	return ret != 0;
+}
+
 static int switch_branches(const struct checkout_opts *opts,
 			   struct branch_info *new_branch_info)
 {
@@ -1165,6 +1136,8 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	const char *stash_label_ancestor = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1202,10 +1175,34 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_ancestor = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_ancestor = old_commit_shortname.buf;
+	}
+
+	if (opts->merge) {
+		if (repo_read_index(the_repository) < 0)
+			die(_("index file corrupt"));
+		if (checkout_would_clobber_changes(&old_branch_info,
+						   new_branch_info))
+			create_autostash_ref_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH");
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_ancestor);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
 			return ret;
 		}
 	}
@@ -1215,8 +1212,28 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
+				       new_branch_info->name, "local",
+				       stash_label_ancestor);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
 
 	return ret || writeout_error;
 }
diff --git a/builtin/stash.c b/builtin/stash.c
index e79d612e57..1016d88e52 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label1, const char *label2,
+				      const char *label_ancestor)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label1 ? label1 : "Updated upstream";
+	o.branch2 = label2 ? label2 : "Stashed changes";
+	o.ancestor = label_ancestor ? label_ancestor : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label1 = NULL, *label2 = NULL, *label_ancestor = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "ours-label", &label1, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "theirs-label", &label2, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "base-label", &label_ancestor, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label1, label2, label_ancestor);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/sequencer.c b/sequencer.c
index aafd0bc959..53e04d8a94 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4632,7 +4632,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      int silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4677,7 +4678,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4689,15 +4691,22 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, 0);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, 0);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, 1);
+}
+
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4708,6 +4717,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label1)
+			strvec_pushf(&child.args, "--ours-label=%s", label1);
+		if (label2)
+			strvec_pushf(&child.args, "--theirs-label=%s", label2);
+		if (label_ancestor)
+			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4726,15 +4741,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
@@ -4752,7 +4775,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4771,11 +4795,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4791,7 +4817,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label1, label2, label_ancestor);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4801,12 +4828,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label1, label2, label_ancestor);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 719684c8a9..68b94d86e3 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -227,11 +227,15 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..f4fea7bb7a 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,166 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..b061cc1b4a 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -342,7 +342,7 @@ test_expect_success 'merge --squash --autostash conflict does not attempt to app
 	>unrelated &&
 	git add unrelated &&
 	test_must_fail git merge --squash c7 --autostash >out 2>err &&
-	! grep "Applying autostash resulted in conflicts." err &&
+	! grep "resulted in conflicts" err &&
 	grep "When finished, apply stashed changes with \`git stash pop\`" out
 '
 
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;

base-commit: dc6ecd5354dca88d51b6d6562777fc8fc10d77e1
-- 
gitgitgadget

Re: [PATCH v4] checkout: -m (--merge) uses autostash when switching branches

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> When switching branches with "git checkout -m", local modifications
> can block the switch.  Teach the -m flow to create a temporary stash
> before switching and reapply it after.  On success, only "Applied
> autostash." is shown.  If reapplying causes conflicts, the stash is
> kept and the user is told they can resolve and run "git stash drop",
> or run "git reset --hard" and later "git stash pop" to recover their
> changes.
>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>     checkout: 'autostash' for branch switching
>     
>     cc: Phillip Wood phillip.wood123@gmail.com

I very much appreciate this, but somehow this "cc:" seems to have
been ignored.

>  Documentation/git-checkout.adoc |  56 +++++-----
>  Documentation/git-switch.adoc   |  26 ++---
>  builtin/checkout.c              | 179 +++++++++++++++++---------------
>  builtin/stash.c                 |  30 ++++--
>  sequencer.c                     |  67 +++++++++---
>  sequencer.h                     |   4 +
>  t/t3420-rebase-autostash.sh     |  24 +++--
>  t/t7201-co.sh                   | 160 ++++++++++++++++++++++++++++
>  t/t7600-merge.sh                |   4 +-
>  xdiff-interface.c               |  12 +++
>  xdiff-interface.h               |   1 +
>  11 files changed, 412 insertions(+), 151 deletions(-)
>
> diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
> index 43ccf47cf6..9d5f5c51ae 100644
> --- a/Documentation/git-checkout.adoc
> +++ b/Documentation/git-checkout.adoc
> @@ -251,20 +251,17 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
>  	are different between the current branch and the branch to
>  	which you are switching, the command refuses to switch
>  	branches in order to preserve your modifications in context.
> -	However, with this option, a three-way merge between the current
> -	branch, your working tree contents, and the new branch
> -	is done, and you will be on the new branch.
> -+
> -When a merge conflict happens, the index entries for conflicting
> -paths are left unmerged, and you need to resolve the conflicts
> -and mark the resolved paths with `git add` (or `git rm` if the merge
> -should result in deletion of the path).
> +	With this option, the conflicting local changes are
> +	automatically stashed before the switch and reapplied
> +	afterwards.  If the local changes do not overlap with the
> +	differences between branches, the switch proceeds without
> +	stashing.  If reapplying the stash results in conflicts, the
> +	entry is saved to the stash list so you can use `git stash
> +	pop` to recover and `git stash drop` when done.

The new conflict message in sequencer.c correctly points out that,
if the user wants to use `git stash pop`, they would first need to
clear the working tree (e.g. `git reset --hard`) because the
conflicted changes are already there.

The documentation here is a bit too simplified and may give the
impression that `git stash pop` is the immediate next step when
conflicts are present in the worktree, which is probably something
we want to avoid.

>  ------------
>  $ git checkout -m mytopic
> -Auto-merging frotz
> +Applied autostash.
>  ------------

I must be utterly confused, but the documentation _before_ this
patch does not seem to match the reality.  In the following
illustration, I am switching to another branch that has contents in
transport.c that is different from the version in HEAD:

    $ git checkout master
    $ echo >>transport.c
    $ git checkout jk/transport-color-leakfix
    error: Your local changes to the following files would be overwritten...
        transport.c
    Please commit your changes or stash ...
    Aborting
    $ git checkout -m jk/transport-color-leakfix
    M	transport.c
    Switched to branch 'jk/transport-color-leakfix'

Hmmmm.

The new behavior is silent about individual files, and instead
reports "Applied autostash."; even though it is consistent with how
other commands may behave when given the "--autostash" option, I am
not sure if it is even necessary.

Even in the documented version, the "Auto-merging" message is
presumably given only to the paths that needed real content-level
merges, and the paths that went through the trivial tree-level
merges (i.e., paths that are different from HEAD and mytopic but
without local changes) are not reported.  The behaviour I am seeing
does not say anything to either trivially merged or really merged
paths while branch switching is happening, and shows the local
changes at the end of merge_working_tree() by calling
show_local_changes(), which runs "git diff --name-status"
in-process.

In either case, the stashing is a mere implementation detail of
carrying the local changes with you when you move to a different
branch, and moving with your local changes is what "Switching"
branch is about in this system, so I am not sure if we need to say
anything more than the current "Switched to branch 'mytopic'" in the
successful case.

> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index 1d1667fa4c..1968e46ae9 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -17,7 +17,6 @@
>  #include "merge-ll.h"
>  #include "lockfile.h"
>  #include "mem-pool.h"
> -#include "merge-ort-wrappers.h"
>  #include "object-file.h"
>  #include "object-name.h"
>  #include "odb.h"
> @@ -30,6 +29,7 @@
>  #include "repo-settings.h"
>  #include "resolve-undo.h"
>  #include "revision.h"
> +#include "sequencer.h"
>  #include "setup.h"
>  #include "submodule.h"
>  #include "symlinks.h"
> @@ -845,83 +845,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
>  
>  		ret = unpack_trees(2, trees, &topts);
>  		clear_unpack_trees_porcelain(&topts);
> -		if (ret == -1) {
> -...
> -		}
> +		if (ret == -1)
> +			return 1;
>  	}
>  
>  	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
> @@ -930,9 +855,6 @@ static int merge_working_tree(const struct checkout_opts *opts,
>  	if (write_locked_index(the_repository->index, &lock_file, COMMIT_LOCK))
>  		die(_("unable to write new index file"));
>  
> -	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
> -		show_local_changes(&new_branch_info->commit->object, &opts->diff_options);

Ah, this is what you lost.  I do not see a reason why we would want
to lose it.

> +static int checkout_would_clobber_changes(struct branch_info *old_branch_info,
> +					  struct branch_info *new_branch_info)
> +{
> +...
> +	init_tree_desc(&trees[0], &old_tree->object.oid,
> +		       old_tree->buffer, old_tree->size);
> +	init_tree_desc(&trees[1], &new_tree->object.oid,
> +		       new_tree->buffer, new_tree->size);
> +
> +	ret = unpack_trees(2, trees, &topts);
> +	discard_index(&tmp_index);

In my original outline, I did suggest 

 - check if the local changes overlap with paths that differ between
   HEAD and the new branch, and if not, we need no stashing;
   otherwise stash.

 - then switch branches with two-way merge

 - then unstash.

But my untold assumption was that the initial check was done by
running a moral equivalent of "git diff --name-only HEAD <branch>"
to obtain the list of paths that differ between branches, and
a "git diff HEAD" to obtain the list of paths with local changes.

If you are using the real branch switching machinery in the
"dry-run" mode, then it is a waste to discard when we find out that
there is no overlap.  So if I knew you would use the unpack-trees in
the dry-run mode, instead of two diffs, the outline would have been
more like

 - Try unpack-trees in dry-run mode to see if there would get any
   failure from overlap.

 - If unpack-trees would succeed, we already have the right contents
   in the index after the above dry-run.  We did not touch the
   working tree so far, but if we kept track of which paths we would
   have written out to the working tree during our dry-run, we can
   write them out of the index at this point and we are done (we of
   course need to update HEAD to point at the new branch, give the
   "Switched to branch 'foo'" message, etc., but the real work of
   switching branches is done).

 - If not, discard the dry-run index, stash, switch branches the
   usual way, and unstash.

which might be more performant in a large tree.

Having said all that, what we see above, while running the same
unpack-trees once in dry-run mode and another for real, may be
performant enough and complicating the dry-run code might not be
worth it.

> @@ -1165,6 +1136,8 @@ static int switch_branches(const struct checkout_opts *opts,
>  	struct object_id rev;
>  	int flag, writeout_error = 0;
>  	int do_merge = 1;
> +	struct strbuf old_commit_shortname = STRBUF_INIT;
> +	const char *stash_label_ancestor = NULL;
>  
>  	trace2_cmd_mode("branch");
>  
> @@ -1202,10 +1175,34 @@ static int switch_branches(const struct checkout_opts *opts,
>  			do_merge = 0;
>  	}
>  
> +	if (old_branch_info.name)
> +		stash_label_ancestor = old_branch_info.name;
> +	else if (old_branch_info.commit) {
> +		strbuf_add_unique_abbrev(&old_commit_shortname,
> +					 &old_branch_info.commit->object.oid,
> +					 DEFAULT_ABBREV);
> +		stash_label_ancestor = old_commit_shortname.buf;
> +	}
> +
> +	if (opts->merge) {
> +		if (repo_read_index(the_repository) < 0)
> +			die(_("index file corrupt"));
> +		if (checkout_would_clobber_changes(&old_branch_info,
> +						   new_branch_info))
> +			create_autostash_ref_silent(the_repository,
> +						   "CHECKOUT_AUTOSTASH");
> +	}
> +
>  	if (do_merge) {
>  		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>  		if (ret) {
> +			apply_autostash_ref_with_labels(the_repository,
> +						       "CHECKOUT_AUTOSTASH",
> +						       new_branch_info->name,
> +						       "local",
> +						       stash_label_ancestor);
>  			branch_info_release(&old_branch_info);
> +			strbuf_release(&old_commit_shortname);
>  			return ret;
>  		}
>  	}

Nice changes to preserve the conflict marker labels.

> diff --git a/builtin/stash.c b/builtin/stash.c
> index e79d612e57..1016d88e52 100644
> --- a/builtin/stash.c
> +++ b/builtin/stash.c

This can and should become a separate patch that is a preliminary
preparation step, [1/2], with its own documentation and test, only
about teaching "git stash" command a set of new options to use
custom conflict labels, I think.  And on top of it, patch [2/2] that
updates "checkout -m" to use the improved "git stash" with custom
labels support is written.  It would give us a clean logical
progression of the series.

> diff --git a/sequencer.c b/sequencer.c
> index aafd0bc959..53e04d8a94 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4632,7 +4632,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
>  
>  static void create_autostash_internal(struct repository *r,
>  				      const char *path,
> -				      const char *refname)
> +				      const char *refname,
> +				      int silent)
>  {
>  	struct strbuf buf = STRBUF_INIT;
>  	struct lock_file lock_file = LOCK_INIT;
> @@ -4677,7 +4678,8 @@ static void create_autostash_internal(struct repository *r,
>  					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
>  		}
>  
> -		printf(_("Created autostash: %s\n"), buf.buf);
> +		if (!silent)
> +			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
>  		if (reset_head(r, &ropts) < 0)
>  			die(_("could not reset --hard"));
>  		discard_index(r->index);
> @@ -4689,15 +4691,22 @@ static void create_autostash_internal(struct repository *r,
>  
>  void create_autostash(struct repository *r, const char *path)
>  {
> -	create_autostash_internal(r, path, NULL);
> +	create_autostash_internal(r, path, NULL, 0);
>  }
>  
>  void create_autostash_ref(struct repository *r, const char *refname)
>  {
> -	create_autostash_internal(r, NULL, refname);
> +	create_autostash_internal(r, NULL, refname, 0);
>  }
>  
> -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
> +void create_autostash_ref_silent(struct repository *r, const char *refname)
> +{
> +	create_autostash_internal(r, NULL, refname, 1);
> +}

Changes around here to optionally squelch message(s) is better
presented as yet another preliminary preparation step, I think.

> @@ -4752,7 +4775,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
>  	}
>  	strbuf_trim(&stash_oid);
>  
> -	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
> +	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
> +				      NULL, NULL, NULL);
>  
>  	unlink(path);
>  	strbuf_release(&stash_oid);
> @@ -4771,11 +4795,13 @@ int apply_autostash(const char *path)
>  
>  int apply_autostash_oid(const char *stash_oid)
>  {
> -	return apply_save_autostash_oid(stash_oid, 1);
> +	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
>  }
>  
>  static int apply_save_autostash_ref(struct repository *r, const char *refname,
> -				    int attempt_apply)
> +				    int attempt_apply,
> +				    const char *label1, const char *label2,
> +				    const char *label_ancestor)
>  {
>  	struct object_id stash_oid;
>  	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
> @@ -4791,7 +4817,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
>  		return error(_("autostash reference is a symref"));
>  
>  	oid_to_hex_r(stash_oid_hex, &stash_oid);
> -	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
> +	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
> +				       label1, label2, label_ancestor);
>  
>  	refs_delete_ref(get_main_ref_store(r), "", refname,
>  			&stash_oid, REF_NO_DEREF);
>
> @@ -4801,12 +4828,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
>  
>  int save_autostash_ref(struct repository *r, const char *refname)
>  {
> -	return apply_save_autostash_ref(r, refname, 0);
> +	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
>  }
>  
>  int apply_autostash_ref(struct repository *r, const char *refname)
>  {
> -	return apply_save_autostash_ref(r, refname, 1);
> +	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
> +}
> +
> +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
> +				    const char *label1, const char *label2,
> +				    const char *label_ancestor)
> +{
> +	return apply_save_autostash_ref(r, refname, 1,
> +					label1, label2, label_ancestor);
>  }
>  
>  static int checkout_onto(struct repository *r, struct replay_opts *opts,

So are these, to teach the machinery to take optional conflict
marker labels.

Thanks.

[PATCH v5 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

cc: Phillip Wood phillip.wood123@gmail.com

Harald Nordgren (4):
  stash: add --ours-label, --theirs-label, --base-label for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  27 ++---
 builtin/checkout.c              | 180 ++++++++++++++++++--------------
 builtin/stash.c                 |  32 ++++--
 sequencer.c                     |  67 +++++++++---
 sequencer.h                     |   4 +
 t/t3420-rebase-autostash.sh     |  24 +++--
 t/t3903-stash.sh                |  18 ++++
 t/t7201-co.sh                   | 160 ++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 13 files changed, 447 insertions(+), 149 deletions(-)


base-commit: dc6ecd5354dca88d51b6d6562777fc8fc10d77e1
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v5
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v5
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v4:

 -:  ---------- > 1:  00d8920498 stash: add --ours-label, --theirs-label, --base-label for apply
 -:  ---------- > 2:  5d176f1700 sequencer: allow create_autostash to run silently
 -:  ---------- > 3:  3d6829438a sequencer: teach autostash apply to take optional conflict marker labels
 1:  5d49c0031a ! 4:  7f3735d40e checkout: -m (--merge) uses autostash when switching branches
     @@ Documentation/git-checkout.adoc: working tree, by copying them from elsewhere, e
      +	afterwards.  If the local changes do not overlap with the
      +	differences between branches, the switch proceeds without
      +	stashing.  If reapplying the stash results in conflicts, the
     -+	entry is saved to the stash list so you can use `git stash
     -+	pop` to recover and `git stash drop` when done.
     ++	entry is saved to the stash list.  Resolve the conflicts
     ++	and run `git stash drop` when done, or clear the working
     ++	tree (e.g. with `git reset --hard`) before running `git stash
     ++	pop` later to re-apply your changes.
       +
       When checking out paths from the index, this option lets you recreate
       the conflicted merge in the specified paths.  This option cannot be
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
       
      -You can give the `-m` flag to the command, which would try a
      -three-way merge:
     -+You can give the `-m` flag to the command, which would save the local
     -+changes in a stash entry and reset the working tree to allow switching:
     ++You can give the `-m` flag to the command, which would carry your local
     ++changes to the new branch:
       
       ------------
       $ git checkout -m mytopic
      -Auto-merging frotz
     -+Applied autostash.
     ++Switched to branch 'mytopic'
       ------------
       
      -After this three-way merge, the local modifications are _not_
     @@ Documentation/git-switch.adoc: variable.
      +	local changes do not overlap with the differences between
      +	branches, the switch proceeds without stashing.  If
      +	reapplying the stash results in conflicts, the entry is
     -+	saved to the stash list so you can use `git stash pop` to
     -+	recover and `git stash drop` when done.
     ++	saved to the stash list.  Resolve the conflicts and run
     ++	`git stash drop` when done, or clear the working tree
     ++	(e.g. with `git reset --hard`) before running `git stash pop`
     ++	later to re-apply your changes.
       
       `--conflict=<style>`::
       	The same as `--merge` option above, but changes the way the
     @@ Documentation/git-switch.adoc: $ git switch mytopic
       
      -You can give the `-m` flag to the command, which would try a three-way
      -merge:
     -+You can give the `-m` flag to the command, which would save the local
     -+changes in a stash entry and reset the working tree to allow switching:
     ++You can give the `-m` flag to the command, which would carry your local
     ++changes to the new branch:
       
       ------------
       $ git switch -m mytopic
      -Auto-merging frotz
     -+Created autostash: 7a9afa3
     -+Applied autostash.
     ++Switched to branch 'mytopic'
       ------------
       
      -After this three-way merge, the local modifications are _not_
     @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
       	}
       
       	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
     -@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     - 	if (write_locked_index(the_repository->index, &lock_file, COMMIT_LOCK))
     - 		die(_("unable to write new index file"));
     - 
     --	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
     --		show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
     --
     - 	return 0;
     - }
     - 
      @@ builtin/checkout.c: static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
       	release_revisions(&revs);
       }
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	struct object_id rev;
       	int flag, writeout_error = 0;
       	int do_merge = 1;
     ++	int created_autostash = 0;
      +	struct strbuf old_commit_shortname = STRBUF_INIT;
      +	const char *stash_label_ancestor = NULL;
       
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +		if (repo_read_index(the_repository) < 0)
      +			die(_("index file corrupt"));
      +		if (checkout_would_clobber_changes(&old_branch_info,
     -+						   new_branch_info))
     ++						   new_branch_info)) {
      +			create_autostash_ref_silent(the_repository,
      +						   "CHECKOUT_AUTOSTASH");
     ++			created_autostash = 1;
     ++		}
      +	}
      +
       	if (do_merge) {
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +	if (repo_read_index(the_repository) < 0)
      +		die(_("index file corrupt"));
      +
     -+	if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
     ++	if (created_autostash && !opts->discard_changes && !opts->quiet &&
     ++	    new_branch_info->commit)
      +		show_local_changes(&new_branch_info->commit->object,
      +				   &opts->diff_options);
      +
     @@ builtin/stash.c: static int apply_stash(int argc, const char **argv, const char
       	return ret;
      
       ## sequencer.c ##
     -@@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list, int offset)
     - 
     - static void create_autostash_internal(struct repository *r,
     - 				      const char *path,
     --				      const char *refname)
     -+				      const char *refname,
     -+				      int silent)
     - {
     - 	struct strbuf buf = STRBUF_INIT;
     - 	struct lock_file lock_file = LOCK_INIT;
     -@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     - 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
     - 		}
     - 
     --		printf(_("Created autostash: %s\n"), buf.buf);
     -+		if (!silent)
     -+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
     - 		if (reset_head(r, &ropts) < 0)
     - 			die(_("could not reset --hard"));
     - 		discard_index(r->index);
     -@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     - 
     - void create_autostash(struct repository *r, const char *path)
     - {
     --	create_autostash_internal(r, path, NULL);
     -+	create_autostash_internal(r, path, NULL, 0);
     - }
     - 
     - void create_autostash_ref(struct repository *r, const char *refname)
     - {
     --	create_autostash_internal(r, NULL, refname);
     -+	create_autostash_internal(r, NULL, refname, 0);
     - }
     - 
     --static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     -+void create_autostash_ref_silent(struct repository *r, const char *refname)
     -+{
     -+	create_autostash_internal(r, NULL, refname, 1);
     -+}
     -+
     -+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor)
     - {
     - 	struct child_process child = CHILD_PROCESS_INIT;
     - 	int ret = 0;
     -@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     - 		child.no_stderr = 1;
     - 		strvec_push(&child.args, "stash");
     - 		strvec_push(&child.args, "apply");
     -+		if (label1)
     -+			strvec_pushf(&child.args, "--ours-label=%s", label1);
     -+		if (label2)
     -+			strvec_pushf(&child.args, "--theirs-label=%s", label2);
     -+		if (label_ancestor)
     -+			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);
     - 		strvec_push(&child.args, stash_oid);
     - 		ret = run_command(&child);
     - 	}
     -@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     +@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
       		strvec_push(&store.args, stash_oid);
       		if (run_command(&store))
       			ret = error(_("cannot store %s"), stash_oid);
     @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
       	}
       
       	return ret;
     -@@ sequencer.c: static int apply_save_autostash(const char *path, int attempt_apply)
     - 	}
     - 	strbuf_trim(&stash_oid);
     - 
     --	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
     -+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
     -+				      NULL, NULL, NULL);
     - 
     - 	unlink(path);
     - 	strbuf_release(&stash_oid);
     -@@ sequencer.c: int apply_autostash(const char *path)
     - 
     - int apply_autostash_oid(const char *stash_oid)
     - {
     --	return apply_save_autostash_oid(stash_oid, 1);
     -+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
     - }
     - 
     - static int apply_save_autostash_ref(struct repository *r, const char *refname,
     --				    int attempt_apply)
     -+				    int attempt_apply,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor)
     - {
     - 	struct object_id stash_oid;
     - 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
     -@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     - 		return error(_("autostash reference is a symref"));
     - 
     - 	oid_to_hex_r(stash_oid_hex, &stash_oid);
     --	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
     -+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
     -+				       label1, label2, label_ancestor);
     - 
     - 	refs_delete_ref(get_main_ref_store(r), "", refname,
     - 			&stash_oid, REF_NO_DEREF);
     -@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     - 
     - int save_autostash_ref(struct repository *r, const char *refname)
     - {
     --	return apply_save_autostash_ref(r, refname, 0);
     -+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
     - }
     - 
     - int apply_autostash_ref(struct repository *r, const char *refname)
     - {
     --	return apply_save_autostash_ref(r, refname, 1);
     -+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
     -+}
     -+
     -+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor)
     -+{
     -+	return apply_save_autostash_ref(r, refname, 1,
     -+					label1, label2, label_ancestor);
     - }
     - 
     - static int checkout_onto(struct repository *r, struct replay_opts *opts,
     -
     - ## sequencer.h ##
     -@@ sequencer.h: void commit_post_rewrite(struct repository *r,
     - 
     - void create_autostash(struct repository *r, const char *path);
     - void create_autostash_ref(struct repository *r, const char *refname);
     -+void create_autostash_ref_silent(struct repository *r, const char *refname);
     - int save_autostash(const char *path);
     - int save_autostash_ref(struct repository *r, const char *refname);
     - int apply_autostash(const char *path);
     - int apply_autostash_oid(const char *stash_oid);
     - int apply_autostash_ref(struct repository *r, const char *refname);
     -+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor);
     - 
     - #define SUMMARY_INITIAL_COMMIT   (1 << 0)
     - #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
      
       ## t/t3420-rebase-autostash.sh ##
      @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
       	git reset --hard &&
      
       ## t/t7600-merge.sh ##
     -@@ t/t7600-merge.sh: test_expect_success 'merge --squash --autostash conflict does not attempt to app
     - 	>unrelated &&
     - 	git add unrelated &&
     - 	test_must_fail git merge --squash c7 --autostash >out 2>err &&
     --	! grep "Applying autostash resulted in conflicts." err &&
     -+	! grep "resulted in conflicts" err &&
     - 	grep "When finished, apply stashed changes with \`git stash pop\`" out
     - '
     - 
      @@ t/t7600-merge.sh: test_expect_success 'merge with conflicted --autostash changes' '
       	git diff >expect &&
       	test_when_finished "test_might_fail git stash drop" &&
       	git merge --autostash c3 2>err &&
      -	test_grep "Applying autostash resulted in conflicts." err &&
     -+	test_grep "resulted in conflicts" err &&
     ++	test_grep "your local changes resulted in conflicts" err &&
       	git show HEAD:file >merge-result &&
       	test_cmp result.1-9 merge-result &&
       	git stash show -p >actual &&

-- 
gitgitgadget

[PATCH v5 1/4] stash: add --ours-label, --theirs-label, --base-label for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              |  2 +-
 t/t3903-stash.sh             | 18 ++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index 235d57ddd8..43650a3c1a 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -197,6 +197,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--ours-label=<label>`::
+`--theirs-label=<label>`::
+`--base-label=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--base-label` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index e79d612e57..252e4df3a9 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..dd47c1322a 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,24 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		echo base >file &&
+		git add file &&
+		git commit -m base &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		echo upstream >file &&
+		git add file &&
+		git commit -m upstream &&
+		test_must_fail git stash apply --ours-label=UP --theirs-label=STASH &&
+		grep "^<<<<<<< UP" file &&
+		grep "^>>>>>>> STASH" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
-- 
gitgitgadget

[PATCH v5 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.  Use stderr for
the message when not silent.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 15 +++++++++++----
 sequencer.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index aafd0bc959..eebefd731b 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4632,7 +4632,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      int silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4677,7 +4678,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4689,12 +4691,17 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, 0);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, 0);
+}
+
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, 1);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index 719684c8a9..0b09d6799b 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -227,6 +227,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v5 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label1, label2, and label_ancestor parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --ours-label/--theirs-label/--base-label".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 34 +++++++++++++++++++++++++++-------
 sequencer.h |  3 +++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index eebefd731b..080a25820a 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4704,7 +4704,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, 1);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4715,6 +4717,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label1)
+			strvec_pushf(&child.args, "--ours-label=%s", label1);
+		if (label2)
+			strvec_pushf(&child.args, "--theirs-label=%s", label2);
+		if (label_ancestor)
+			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4759,7 +4767,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4778,11 +4787,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4798,7 +4809,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label1, label2, label_ancestor);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4808,12 +4820,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label1, label2, label_ancestor);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 0b09d6799b..68b94d86e3 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -233,6 +233,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v5 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-switch.adoc   |  27 ++---
 builtin/checkout.c              | 180 ++++++++++++++++++--------------
 builtin/stash.c                 |  30 ++++--
 sequencer.c                     |  18 +++-
 t/t3420-rebase-autostash.sh     |  24 +++--
 t/t7201-co.sh                   | 160 ++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 10 files changed, 376 insertions(+), 136 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..18022e610e 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If the stash application results in conflicts, they are not
+resolved and the stash is saved to the stash list:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..3147023dc3 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -126,15 +126,16 @@ variable.
 	If you have local modifications to one or more files that are
 	different between the current branch and the branch to which
 	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	order to preserve your modifications in context.  With this
+	option, the conflicting local changes are automatically
+	stashed before the switch and reapplied afterwards.  If the
+	local changes do not overlap with the differences between
+	branches, the switch proceeds without stashing.  If
+	reapplying the stash results in conflicts, the entry is
+	saved to the stash list.  Resolve the conflicts and run
+	`git stash drop` when done, or clear the working tree
+	(e.g. with `git reset --hard`) before running `git stash pop`
+	later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 1d1667fa4c..db93eabd9b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -845,83 +845,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
-		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
-		}
+		if (ret == -1)
+			return 1;
 	}
 
 	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
@@ -1157,6 +1082,55 @@ static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
 	release_revisions(&revs);
 }
 
+static int checkout_would_clobber_changes(struct branch_info *old_branch_info,
+					  struct branch_info *new_branch_info)
+{
+	struct tree_desc trees[2];
+	struct tree *old_tree, *new_tree;
+	struct unpack_trees_options topts;
+	struct index_state tmp_index = INDEX_STATE_INIT(the_repository);
+	const struct object_id *old_commit_oid;
+	int ret;
+
+	if (!new_branch_info->commit)
+		return 0;
+
+	old_commit_oid = old_branch_info->commit ?
+		&old_branch_info->commit->object.oid :
+		the_hash_algo->empty_tree;
+	old_tree = repo_parse_tree_indirect(the_repository, old_commit_oid);
+	if (!old_tree)
+		return 0;
+
+	new_tree = repo_get_commit_tree(the_repository,
+					new_branch_info->commit);
+	if (!new_tree)
+		return 0;
+	if (repo_parse_tree(the_repository, new_tree) < 0)
+		return 0;
+
+	memset(&topts, 0, sizeof(topts));
+	topts.head_idx = -1;
+	topts.src_index = the_repository->index;
+	topts.dst_index = &tmp_index;
+	topts.initial_checkout = is_index_unborn(the_repository->index);
+	topts.merge = 1;
+	topts.update = 1;
+	topts.dry_run = 1;
+	topts.quiet = 1;
+	topts.fn = twoway_merge;
+
+	init_tree_desc(&trees[0], &old_tree->object.oid,
+		       old_tree->buffer, old_tree->size);
+	init_tree_desc(&trees[1], &new_tree->object.oid,
+		       new_tree->buffer, new_tree->size);
+
+	ret = unpack_trees(2, trees, &topts);
+	discard_index(&tmp_index);
+
+	return ret != 0;
+}
+
 static int switch_branches(const struct checkout_opts *opts,
 			   struct branch_info *new_branch_info)
 {
@@ -1165,6 +1139,9 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	const char *stash_label_ancestor = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1202,10 +1179,36 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_ancestor = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_ancestor = old_commit_shortname.buf;
+	}
+
+	if (opts->merge) {
+		if (repo_read_index(the_repository) < 0)
+			die(_("index file corrupt"));
+		if (checkout_would_clobber_changes(&old_branch_info,
+						   new_branch_info)) {
+			create_autostash_ref_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH");
+			created_autostash = 1;
+		}
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_ancestor);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
 			return ret;
 		}
 	}
@@ -1215,8 +1218,29 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
+				       new_branch_info->name, "local",
+				       stash_label_ancestor);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
 
 	return ret || writeout_error;
 }
diff --git a/builtin/stash.c b/builtin/stash.c
index 252e4df3a9..ab9c1359b1 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label1, const char *label2,
+				      const char *label_ancestor)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label1 ? label1 : "Updated upstream";
+	o.branch2 = label2 ? label2 : "Stashed changes";
+	o.ancestor = label_ancestor ? label_ancestor : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label1 = NULL, *label2 = NULL, *label_ancestor = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "ours-label", &label1, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "theirs-label", &label2, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "base-label", &label_ancestor, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label1, label2, label_ancestor);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/sequencer.c b/sequencer.c
index 080a25820a..53e04d8a94 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4741,15 +4741,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..f4fea7bb7a 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,166 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

[PATCH v6 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

cc: Phillip Wood phillip.wood123@gmail.com

Harald Nordgren (4):
  stash: add --ours-label, --theirs-label, --base-label for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 ++++++------
 Documentation/git-stash.adoc    |  11 ++-
 Documentation/git-switch.adoc   |  27 +++---
 builtin/checkout.c              | 137 ++++++++++++---------------
 builtin/stash.c                 |  32 +++++--
 sequencer.c                     |  67 +++++++++----
 sequencer.h                     |   4 +
 t/t3420-rebase-autostash.sh     |  24 +++--
 t/t3903-stash.sh                |  18 ++++
 t/t7201-co.sh                   | 160 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 13 files changed, 403 insertions(+), 150 deletions(-)


base-commit: ca1db8a0f7dc0dbea892e99f5b37c5fe5861be71
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v6
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v6
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v5:

 1:  00d8920498 = 1:  cd9c64ba60 stash: add --ours-label, --theirs-label, --base-label for apply
 2:  5d176f1700 = 2:  d572c4bb7d sequencer: allow create_autostash to run silently
 3:  3d6829438a = 3:  80a98116fc sequencer: teach autostash apply to take optional conflict marker labels
 4:  7f3735d40e ! 4:  7ecb0835b7 checkout: -m (--merge) uses autostash when switching branches
     @@ builtin/checkout.c
       #include "submodule.h"
       #include "symlinks.h"
      @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     + 	struct tree *new_tree;
       
     + 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
     +-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
     ++	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
     ++		rollback_lock_file(&lock_file);
     + 		return error(_("index file corrupt"));
     ++	}
     + 
     + 	resolve_undo_clear_index(the_repository->index);
     + 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
     +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     + 	} else {
     + 		new_tree = repo_get_commit_tree(the_repository,
     + 						new_branch_info->commit);
     +-		if (!new_tree)
     ++		if (!new_tree) {
     ++			rollback_lock_file(&lock_file);
     + 			return error(_("unable to read tree (%s)"),
     + 				     oid_to_hex(&new_branch_info->commit->object.oid));
     ++		}
     + 	}
     + 	if (opts->discard_changes) {
     + 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
     +-		if (ret)
     ++		if (ret) {
     ++			rollback_lock_file(&lock_file);
     + 			return ret;
     ++		}
     + 	} else {
     + 		struct tree_desc trees[2];
     + 		struct tree *tree;
     +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     + 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
     + 
     + 		if (unmerged_index(the_repository->index)) {
     ++			rollback_lock_file(&lock_file);
     + 			error(_("you need to resolve your current index first"));
     + 			return 1;
     + 		}
     +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
       		ret = unpack_trees(2, trees, &topts);
       		clear_unpack_trees_porcelain(&topts);
     --		if (ret == -1) {
     + 		if (ret == -1) {
      -			/*
      -			 * Unpack couldn't do a trivial merge; either
      -			 * give up or do a real merge, depending on
     @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
      -			strbuf_release(&old_commit_shortname);
      -			if (ret)
      -				return ret;
     --		}
     -+		if (ret == -1)
     ++			rollback_lock_file(&lock_file);
      +			return 1;
     + 		}
       	}
       
     - 	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
     -@@ builtin/checkout.c: static void orphaned_commit_warning(struct commit *old_commit, struct commit *ne
     - 	release_revisions(&revs);
     - }
     - 
     -+static int checkout_would_clobber_changes(struct branch_info *old_branch_info,
     -+					  struct branch_info *new_branch_info)
     -+{
     -+	struct tree_desc trees[2];
     -+	struct tree *old_tree, *new_tree;
     -+	struct unpack_trees_options topts;
     -+	struct index_state tmp_index = INDEX_STATE_INIT(the_repository);
     -+	const struct object_id *old_commit_oid;
     -+	int ret;
     -+
     -+	if (!new_branch_info->commit)
     -+		return 0;
     -+
     -+	old_commit_oid = old_branch_info->commit ?
     -+		&old_branch_info->commit->object.oid :
     -+		the_hash_algo->empty_tree;
     -+	old_tree = repo_parse_tree_indirect(the_repository, old_commit_oid);
     -+	if (!old_tree)
     -+		return 0;
     -+
     -+	new_tree = repo_get_commit_tree(the_repository,
     -+					new_branch_info->commit);
     -+	if (!new_tree)
     -+		return 0;
     -+	if (repo_parse_tree(the_repository, new_tree) < 0)
     -+		return 0;
     -+
     -+	memset(&topts, 0, sizeof(topts));
     -+	topts.head_idx = -1;
     -+	topts.src_index = the_repository->index;
     -+	topts.dst_index = &tmp_index;
     -+	topts.initial_checkout = is_index_unborn(the_repository->index);
     -+	topts.merge = 1;
     -+	topts.update = 1;
     -+	topts.dry_run = 1;
     -+	topts.quiet = 1;
     -+	topts.fn = twoway_merge;
     -+
     -+	init_tree_desc(&trees[0], &old_tree->object.oid,
     -+		       old_tree->buffer, old_tree->size);
     -+	init_tree_desc(&trees[1], &new_tree->object.oid,
     -+		       new_tree->buffer, new_tree->size);
     -+
     -+	ret = unpack_trees(2, trees, &topts);
     -+	discard_index(&tmp_index);
     -+
     -+	return ret != 0;
     -+}
     -+
     - static int switch_branches(const struct checkout_opts *opts,
     - 			   struct branch_info *new_branch_info)
     - {
      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	struct object_id rev;
       	int flag, writeout_error = 0;
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +		stash_label_ancestor = old_commit_shortname.buf;
      +	}
      +
     -+	if (opts->merge) {
     -+		if (repo_read_index(the_repository) < 0)
     -+			die(_("index file corrupt"));
     -+		if (checkout_would_clobber_changes(&old_branch_info,
     -+						   new_branch_info)) {
     + 	if (do_merge) {
     + 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
     ++		if (ret && opts->merge) {
      +			create_autostash_ref_silent(the_repository,
      +						   "CHECKOUT_AUTOSTASH");
      +			created_autostash = 1;
     ++			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		}
     -+	}
     -+
     - 	if (do_merge) {
     - 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
       		if (ret) {
      +			apply_autostash_ref_with_labels(the_repository,
      +						       "CHECKOUT_AUTOSTASH",

-- 
gitgitgadget

[PATCH v6 1/4] stash: add --ours-label, --theirs-label, --base-label for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              |  2 +-
 t/t3903-stash.sh             | 18 ++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index 235d57ddd8..43650a3c1a 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -197,6 +197,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--ours-label=<label>`::
+`--theirs-label=<label>`::
+`--base-label=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--base-label` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index e79d612e57..252e4df3a9 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..dd47c1322a 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,24 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		echo base >file &&
+		git add file &&
+		git commit -m base &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		echo upstream >file &&
+		git add file &&
+		git commit -m upstream &&
+		test_must_fail git stash apply --ours-label=UP --theirs-label=STASH &&
+		grep "^<<<<<<< UP" file &&
+		grep "^>>>>>>> STASH" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
-- 
gitgitgadget

[PATCH v6 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.  Use stderr for
the message when not silent.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 15 +++++++++++----
 sequencer.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index aafd0bc959..eebefd731b 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4632,7 +4632,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      int silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4677,7 +4678,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4689,12 +4691,17 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, 0);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, 0);
+}
+
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, 1);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index 719684c8a9..0b09d6799b 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -227,6 +227,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v6 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label1, label2, and label_ancestor parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --ours-label/--theirs-label/--base-label".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 34 +++++++++++++++++++++++++++-------
 sequencer.h |  3 +++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index eebefd731b..080a25820a 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4704,7 +4704,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, 1);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4715,6 +4717,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label1)
+			strvec_pushf(&child.args, "--ours-label=%s", label1);
+		if (label2)
+			strvec_pushf(&child.args, "--theirs-label=%s", label2);
+		if (label_ancestor)
+			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4759,7 +4767,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4778,11 +4787,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4798,7 +4809,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label1, label2, label_ancestor);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4808,12 +4820,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label1, label2, label_ancestor);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 0b09d6799b..68b94d86e3 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -233,6 +233,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v6 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 ++++++------
 Documentation/git-switch.adoc   |  27 +++---
 builtin/checkout.c              | 137 ++++++++++++---------------
 builtin/stash.c                 |  30 ++++--
 sequencer.c                     |  18 +++-
 t/t3420-rebase-autostash.sh     |  24 +++--
 t/t7201-co.sh                   | 160 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 10 files changed, 332 insertions(+), 137 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..18022e610e 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If the stash application results in conflicts, they are not
+resolved and the stash is saved to the stash list:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..3147023dc3 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -126,15 +126,16 @@ variable.
 	If you have local modifications to one or more files that are
 	different between the current branch and the branch to which
 	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	order to preserve your modifications in context.  With this
+	option, the conflicting local changes are automatically
+	stashed before the switch and reapplied afterwards.  If the
+	local changes do not overlap with the differences between
+	branches, the switch proceeds without stashing.  If
+	reapplying the stash results in conflicts, the entry is
+	saved to the stash list.  Resolve the conflicts and run
+	`git stash drop` when done, or clear the working tree
+	(e.g. with `git reset --hard`) before running `git stash pop`
+	later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 1d1667fa4c..dc935d6bcb 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -846,81 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
+			rollback_lock_file(&lock_file);
+			return 1;
 		}
 	}
 
@@ -1165,6 +1099,9 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	const char *stash_label_ancestor = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1202,10 +1139,31 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_ancestor = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_ancestor = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret && opts->merge) {
+			create_autostash_ref_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH");
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_ancestor);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
 			return ret;
 		}
 	}
@@ -1215,8 +1173,29 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
+				       new_branch_info->name, "local",
+				       stash_label_ancestor);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
 
 	return ret || writeout_error;
 }
diff --git a/builtin/stash.c b/builtin/stash.c
index 252e4df3a9..ab9c1359b1 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label1, const char *label2,
+				      const char *label_ancestor)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label1 ? label1 : "Updated upstream";
+	o.branch2 = label2 ? label2 : "Stashed changes";
+	o.ancestor = label_ancestor ? label_ancestor : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label1 = NULL, *label2 = NULL, *label_ancestor = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "ours-label", &label1, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "theirs-label", &label2, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "base-label", &label_ancestor, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label1, label2, label_ancestor);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/sequencer.c b/sequencer.c
index 080a25820a..53e04d8a94 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4741,15 +4741,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..f4fea7bb7a 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,166 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

[PATCH v7 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Harald Nordgren (4):
  stash: add --ours-label, --theirs-label, --base-label for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  27 ++---
 builtin/checkout.c              | 138 ++++++++++-------------
 builtin/stash.c                 |  32 ++++--
 sequencer.c                     |  67 +++++++++---
 sequencer.h                     |   4 +
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  18 +++
 t/t7201-co.sh                   | 188 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 13 files changed, 431 insertions(+), 151 deletions(-)


base-commit: b15384c06f77bc2d34d0d3623a8a58218313a561
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v7
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v7
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v6:

 1:  cd9c64ba60 ! 1:  284075600a stash: add --ours-label, --theirs-label, --base-label for apply
     @@ Documentation/git-stash.adoc: git stash list [<log-options>]
      -git stash apply [--index] [-q | --quiet] [<stash>]
      +git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
       git stash branch <branchname> [<stash>]
     - git stash [push [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
     + git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
       	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
      @@ Documentation/git-stash.adoc: the index's ones. However, this can fail, when you have conflicts
       (which are stored in the index, where you therefore can no longer
 2:  d572c4bb7d = 2:  64261e3cb6 sequencer: allow create_autostash to run silently
 3:  80a98116fc = 3:  c0d6b4b4c0 sequencer: teach autostash apply to take optional conflict marker labels
 4:  7ecb0835b7 ! 4:  1c29e19971 checkout: -m (--merge) uses autostash when switching branches
     @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
      -					0, 0);
      -			init_ui_merge_options(&o, the_repository);
      -			o.verbosity = 0;
     --			work = write_in_core_index_as_tree(the_repository);
     +-			work = write_in_core_index_as_tree(the_repository,
     +-							   the_repository->index);
      -
      -			ret = reset_tree(new_tree,
      -					 opts, 1,
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	git reset --hard
      +'
      +
     ++test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
     ++	git checkout -f main &&
     ++	git reset --hard &&
     ++	git clean -f &&
     ++
     ++	git checkout -b nonoverlap_base &&
     ++	fill a b c d >file &&
     ++	git add file &&
     ++	git commit -m "add file" &&
     ++
     ++	git checkout -b nonoverlap_child &&
     ++	fill a b c INSERTED d >file &&
     ++	git commit -a -m "insert line near end of file" &&
     ++
     ++	fill DIRTY a b c INSERTED d >file &&
     ++
     ++	git checkout -m nonoverlap_base 2>stderr &&
     ++	test_grep "Applied autostash" stderr &&
     ++	test_grep ! "resulted in conflicts" stderr &&
     ++
     ++	fill DIRTY a b c d >expect &&
     ++	test_cmp expect file &&
     ++
     ++	git checkout -f main &&
     ++	git branch -D nonoverlap_base &&
     ++	git branch -D nonoverlap_child
     ++'
     ++
      +test_expect_success 'checkout -m -b skips stash with dirty tree' '
      +	git checkout -f main &&
      +	git clean -f &&

-- 
gitgitgadget

[PATCH v7 1/4] stash: add --ours-label, --theirs-label, --base-label for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              |  2 +-
 t/t3903-stash.sh             | 18 ++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..6829ba1140 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--ours-label=<label>`::
+`--theirs-label=<label>`::
+`--base-label=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--base-label` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..54bcb6ac73 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..dd47c1322a 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,24 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		echo base >file &&
+		git add file &&
+		git commit -m base &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		echo upstream >file &&
+		git add file &&
+		git commit -m upstream &&
+		test_must_fail git stash apply --ours-label=UP --theirs-label=STASH &&
+		grep "^<<<<<<< UP" file &&
+		grep "^>>>>>>> STASH" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
-- 
gitgitgadget

Re: [PATCH v7 1/4] stash: add --ours-label, --theirs-label, --base-label for apply

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> Allow callers of "git stash apply" to pass custom labels for conflict
> markers instead of the default "Updated upstream" and "Stashed changes".
> Document the new options and add a test.
>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>  Documentation/git-stash.adoc | 11 ++++++++++-
>  builtin/stash.c              |  2 +-
>  t/t3903-stash.sh             | 18 ++++++++++++++++++
>  3 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
> index b05c990ecd..6829ba1140 100644
> --- a/Documentation/git-stash.adoc
> +++ b/Documentation/git-stash.adoc
> @@ -12,7 +12,7 @@ git stash list [<log-options>]
>  git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
>  git stash drop [-q | --quiet] [<stash>]
>  git stash pop [--index] [-q | --quiet] [<stash>]
> -git stash apply [--index] [-q | --quiet] [<stash>]
> +git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
>  git stash branch <branchname> [<stash>]
>  git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
>  	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
> @@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
>  (which are stored in the index, where you therefore can no longer
>  apply the changes as they were originally).
>  
> +`--ours-label=<label>`::
> +`--theirs-label=<label>`::
> +`--base-label=<label>`::
> +	These options are only valid for the `apply` command.
> ++
> +Use the given labels in conflict markers instead of the default
> +"Updated upstream", "Stashed changes", and "Stash base".
> +`--base-label` only has an effect with merge.conflictStyle=diff3.
> +
>  `-k`::
>  `--keep-index`::
>  `--no-keep-index`::
> diff --git a/builtin/stash.c b/builtin/stash.c
> index 0d27b2fb1f..54bcb6ac73 100644
> --- a/builtin/stash.c
> +++ b/builtin/stash.c
> @@ -44,7 +44,7 @@
>  #define BUILTIN_STASH_POP_USAGE \
>  	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
>  #define BUILTIN_STASH_APPLY_USAGE \
> -	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
> +	N_("git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]")
>  #define BUILTIN_STASH_BRANCH_USAGE \
>  	N_("git stash branch <branchname> [<stash>]")
>  #define BUILTIN_STASH_STORE_USAGE \
> diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
> index 70879941c2..dd47c1322a 100755
> --- a/t/t3903-stash.sh
> +++ b/t/t3903-stash.sh
> @@ -1666,6 +1666,24 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
>  	)
>  '
>  
> +test_expect_success 'apply with custom conflict labels' '
> +	git init conflict_labels &&
> +	(
> +		cd conflict_labels &&
> +		echo base >file &&
> +		git add file &&
> +		git commit -m base &&
> +		echo stashed >file &&
> +		git stash push -m "stashed" &&
> +		echo upstream >file &&
> +		git add file &&
> +		git commit -m upstream &&
> +		test_must_fail git stash apply --ours-label=UP --theirs-label=STASH &&
> +		grep "^<<<<<<< UP" file &&
> +		grep "^>>>>>>> STASH" file
> +	)
> +'

Two and a half things I noticed.

 * use "test_grep" to validate the result, like you did in other
   patches to the tests.  t3903 is rather old and has uses of raw
   "grep" but majority of the tests should already be using
   test_grep.

 * Not validating the base line is a bit unexpected.  Even without
   giving --base-label to the "stash apply" command, we could make
   sure that the output says "|||||||" (and nothing else) for the
   base label.

 * When these labels are set to an empty string, I think we should
   refrain from adding a trailing " " after these marker characters.
   Should we add a test case for that, e.g.

	test_must_fail git stash apply --ours-l= --theirs-l= &&
	test_grep "^<<<<<<<$" file &&
	test_grep "^>>>>>>>$" file

>  test_expect_success 'stash create reports a locked index' '
>  	test_when_finished "rm -rf repo" &&
>  	git init repo &&

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Two and a half things I noticed.
> 
>  * use "test_grep" to validate the result, like you did in other
>    patches to the tests.  t3903 is rather old and has uses of raw
>    "grep" but majority of the tests should already be using
>    test_grep.
> 
>  * Not validating the base line is a bit unexpected.  Even without
>    giving --base-label to the "stash apply" command, we could make
>    sure that the output says "|||||||" (and nothing else) for the
>    base label.
> 
>  * When these labels are set to an empty string, I think we should
>    refrain from adding a trailing " " after these marker characters.
>    Should we add a test case for that, e.g.
> 
>   test_must_fail git stash apply --ours-l= --theirs-l= &&
>   test_grep "^<<<<<<<$" file &&
>   test_grep "^>>>>>>>$" file

Fixed, thanks!


Harald

[PATCH v7 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.  Use stderr for
the message when not silent.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 15 +++++++++++----
 sequencer.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..e500a94a59 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      int silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4702,7 +4703,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4716,17 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, 0);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, 0);
+}
+
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, 1);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..570f804457 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -230,6 +230,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v7 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label1, label2, and label_ancestor parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --ours-label/--theirs-label/--base-label".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 34 +++++++++++++++++++++++++++-------
 sequencer.h |  3 +++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index e500a94a59..79dceab579 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4729,7 +4729,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, 1);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4740,6 +4742,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label1)
+			strvec_pushf(&child.args, "--ours-label=%s", label1);
+		if (label2)
+			strvec_pushf(&child.args, "--theirs-label=%s", label2);
+		if (label_ancestor)
+			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4784,7 +4792,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4803,11 +4812,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4823,7 +4834,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label1, label2, label_ancestor);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4833,12 +4845,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label1, label2, label_ancestor);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 570f804457..1aefd25646 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -236,6 +236,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label1, const char *label2,
+				    const char *label_ancestor);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

Re: [PATCH v7 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> Add label1, label2, and label_ancestor parameters to the autostash
> apply machinery so callers can pass custom conflict marker labels
> through to "git stash apply --ours-label/--theirs-label/--base-label".
> Introduce apply_autostash_ref_with_labels() for callers that want
> to pass labels.

It is just a naming thing, but the contrast between label[12] vs
label_ancestor feel a bit uneven.  Wouldn't it make it easier to
grok a hunk like this, if you stick to ours/theirs/base terminlogy?

> +		if (label1)
> +			strvec_pushf(&child.args, "--ours-label=%s", label1);
> +		if (label2)
> +			strvec_pushf(&child.args, "--theirs-label=%s", label2);
> +		if (label_ancestor)
> +			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);

Alternatively, if you prefer a conciseness of numbered names, it is
customary to use "1" for the common ancestor, "2" for ours, and "3"
for theirs, following the same model after how higher stage index
entries are used during a conflicting merge.

Other than that, this step is quite straight-forward and looking
good.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> It is just a naming thing, but the contrast between label[12] vs
> label_ancestor feel a bit uneven.  Wouldn't it make it easier to
> grok a hunk like this, if you stick to ours/theirs/base terminlogy?

Fixed!


Harald

[PATCH v7 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-switch.adoc   |  27 ++---
 builtin/checkout.c              | 138 ++++++++++-------------
 builtin/stash.c                 |  30 ++++-
 sequencer.c                     |  18 ++-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 188 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 10 files changed, 360 insertions(+), 138 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..18022e610e 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If the stash application results in conflicts, they are not
+resolved and the stash is saved to the stash list:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..3147023dc3 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -126,15 +126,16 @@ variable.
 	If you have local modifications to one or more files that are
 	different between the current branch and the branch to which
 	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	order to preserve your modifications in context.  With this
+	option, the conflicting local changes are automatically
+	stashed before the switch and reapplied afterwards.  If the
+	local changes do not overlap with the differences between
+	branches, the switch proceeds without stashing.  If
+	reapplying the stash results in conflicts, the entry is
+	saved to the stash list.  Resolve the conflicts and run
+	`git stash drop` when done, or clear the working tree
+	(e.g. with `git reset --hard`) before running `git stash pop`
+	later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..283bec2518 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
+			rollback_lock_file(&lock_file);
+			return 1;
 		}
 	}
 
@@ -1166,6 +1099,9 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	const char *stash_label_ancestor = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1203,10 +1139,31 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_ancestor = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_ancestor = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret && opts->merge) {
+			create_autostash_ref_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH");
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_ancestor);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
 			return ret;
 		}
 	}
@@ -1216,8 +1173,29 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
+				       new_branch_info->name, "local",
+				       stash_label_ancestor);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
 
 	return ret || writeout_error;
 }
diff --git a/builtin/stash.c b/builtin/stash.c
index 54bcb6ac73..4c8e8ab59a 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label1, const char *label2,
+				      const char *label_ancestor)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label1 ? label1 : "Updated upstream";
+	o.branch2 = label2 ? label2 : "Stashed changes";
+	o.ancestor = label_ancestor ? label_ancestor : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label1 = NULL, *label2 = NULL, *label_ancestor = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "ours-label", &label1, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "theirs-label", &label2, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "base-label", &label_ancestor, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label1, label2, label_ancestor);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/sequencer.c b/sequencer.c
index 79dceab579..421850f815 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4766,15 +4766,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..857a5a6bd1 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,194 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v7 4/4] checkout: -m (--merge) uses autostash when switching branches

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

>  === 3. Merge conflict
>  
> -When a merge conflict happens during switching branches with
> -the `-m` option, you would see something like this:
> +When the `--merge` (`-m`) option is in effect and the locally
> +modified files overlap with files that need to be updated by the
> +branch switch, the changes are stashed and reapplied after the
> +switch.  If the stash application results in conflicts, they are not
> +resolved and the stash is saved to the stash list:

"results in conflicts, they are not resolved" felt a bit funny thing
to say.  The definition of resulting in conflicits is to be left
with unresolvable conflicts ;-), so ...

    ... and reapplied after the switch.  If this process results in
    conflicts, a stash entry is saved and made available in "git
    stash list".  This is so that you can revisit it in case if you
    fail to resolve conflicts correctly.

or something.  But reading what you have further down, I think the
last sentence "This is so that ..." is probably unnecessary.

> ...
> +Your local changes are stashed, however, applying it to carry
> +forward your local changes resulted in conflicts:
>  
> + - You can try resolving them now.  If you resolved them
> +   successfully, discard the stash entry with "git stash drop".
>  
> + - Alternatively you can "git reset --hard" if you do not want
> +   to deal with them right now, and later "git stash pop" to
> +   recover your local changes.
>  ------------
> +
> +You can try resolving the conflicts now.  Edit the conflicting files
> +and mark them resolved with `git add` as usual, then run `git stash
> +drop` to discard the stash entry.  Alternatively, you can clear the
> +working tree with `git reset --hard` and recover your local changes
> +later with `git stash pop`.

Very well written.  I am very happy to see this text.

> diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
> index 87707e9265..3147023dc3 100644
> --- a/Documentation/git-switch.adoc
> +++ b/Documentation/git-switch.adoc
> @@ -126,15 +126,16 @@ variable.
>  	If you have local modifications to one or more files that are
>  	different between the current branch and the branch to which
>  	you are switching, the command refuses to switch branches in
> +	order to preserve your modifications in context.  With this
> +	option, the conflicting local changes are automatically
> +	stashed before the switch and reapplied afterwards.  If the
> +	local changes do not overlap with the differences between
> +	branches, the switch proceeds without stashing.  If
> +	reapplying the stash results in conflicts, the entry is
> +	saved to the stash list.  Resolve the conflicts and run
> +	`git stash drop` when done, or clear the working tree
> +	(e.g. with `git reset --hard`) before running `git stash pop`
> +	later to re-apply your changes.

We lost "however" but it is OK.

We would want to hint that "The command refuses to" refers to the
default behaviour when option being described ("--merge") is not
given by some other means, which was what the "however" we lost from
the updated text was trying to do.

> @@ -217,15 +218,15 @@ $ git switch mytopic
>  error: You have local changes to 'frotz'; not switching branches.
>  ------------
>  
> -You can give the `-m` flag to the command, which would try a three-way
> -merge:
> +You can give the `-m` flag to the command, which would carry your local
> +changes to the new branch:

Yes, saying "carry your local changes to" is much clearer than "try
a three-way merge".  I very much like this new text.

>  ------------
>  $ git switch -m mytopic
> -Auto-merging frotz
> +Switched to branch 'mytopic'
>  ------------
>  
> -After this three-way merge, the local modifications are _not_
> +After the switch, the local modifications are reapplied and are _not_
>  registered in your index file, so `git diff` would show you what
>  changes you made since the tip of the new branch.


So now to the more exciting part.  But there isn't much to comment
on, as it stayed the same since a previous iteration where Phillip's
excellent "we do not have to waste cycles to dry-run at all" idea.

> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..857a5a6bd1 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -210,6 +210,194 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
>  	test_cmp expect two
>  '
>  
> +test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	fill a b X d e >two &&
> +	git checkout --merge --conflict=zdiff3 simple &&
> +
> +	cat <<-EOF >expect &&
> +	a
> +	<<<<<<< simple
> +	c
> +	||||||| main
> +	b
> +	c
> +	d
> +	=======
> +	b
> +	X
> +	d
> +	>>>>>>> local
> +	e
> +	EOF
> +	test_cmp expect two
> +'

OK.  Do we want to verify with "git stash show -p" or something what
we stashed away?  I see we later have an explicit test to see that
the stash entry can actually be used in "stash pop" after clearing
the stage with "checkout -f", so perhaps it is OK to leave it to
that test, instead of checking in every step.

> +test_expect_success 'checkout -m skips stash when no conflict' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same
> +'

This one may not just check "test_grep !" but also check the output
of "git stash list", perhaps take one before and after "checkout -m"
and compare them?

> +test_expect_success 'checkout -m stashes and applies on conflicting changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 6 7 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "Applied autostash" actual &&
> +	fill 1 2 3 4 5 6 7 >expect &&
> +	test_cmp expect one
> +'

Nice.

> +test_expect_success 'checkout -m stashes on truly conflicting changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	test_must_fail git checkout side 2>stderr &&
> +	test_grep "Your local changes" stderr &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "resulted in conflicts" actual &&
> +	test_grep "git stash drop" actual &&
> +	git stash drop &&
> +	git reset --hard
> +'

OK.  This is an emulation of a user who gives up resolving and punts.

> +test_expect_success 'checkout -m produces usable stash on conflict' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep "recover your local changes" actual &&
> +	git checkout -f main &&
> +	git stash pop &&
> +	fill 1 2 3 4 5 >expect &&
> +	test_cmp expect one
> +'

Nice.

> +test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	git checkout -b nonoverlap_base &&
> +	fill a b c d >file &&
> +	git add file &&
> +	git commit -m "add file" &&
> +
> +	git checkout -b nonoverlap_child &&
> +	fill a b c INSERTED d >file &&
> +	git commit -a -m "insert line near end of file" &&
> +
> +	fill DIRTY a b c INSERTED d >file &&
> +
> +	git checkout -m nonoverlap_base 2>stderr &&
> +	test_grep "Applied autostash" stderr &&
> +	test_grep ! "resulted in conflicts" stderr &&
> +
> +	fill DIRTY a b c d >expect &&
> +	test_cmp expect file &&

Should we or should we not see an extra stack entry saved at this point?
Don't we want to test it?

> +
> +	git checkout -f main &&
> +	git branch -D nonoverlap_base &&
> +	git branch -D nonoverlap_child
> +'

Overall very nicely done.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Should we or should we not see an extra stack entry saved at this point?
> Don't we want to test it?

All of these should be fixed as well. Thanks!


Harald

Re: [PATCH v7 0/4] checkout: 'autostash' for branch switching

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> Harald Nordgren (4):
>   stash: add --ours-label, --theirs-label, --base-label for apply
>   sequencer: allow create_autostash to run silently
>   sequencer: teach autostash apply to take optional conflict marker
>     labels
>   checkout: -m (--merge) uses autostash when switching branches

Thanks for an update.  Above the list of the commits, it would be
helpful to give a summary of the overall goal of the topic (which
typically stays more or less the same during the life of the topic)
and the highlights of the changes since the previous iteration
(which authors often accumulate, so that in a cover letter for v7,
there will be 6 such summaries), if you are sending a cover letter.

I _think_ the change since v6 is a rebasing onto a more recent
'master', and addition of a new test?

Thanks.

>  Documentation/git-checkout.adoc |  58 +++++-----
>  Documentation/git-stash.adoc    |  11 +-
>  Documentation/git-switch.adoc   |  27 ++---
>  builtin/checkout.c              | 138 ++++++++++-------------
>  builtin/stash.c                 |  32 ++++--
>  sequencer.c                     |  67 +++++++++---
>  sequencer.h                     |   4 +
>  t/t3420-rebase-autostash.sh     |  24 +++-
>  t/t3903-stash.sh                |  18 +++
>  t/t7201-co.sh                   | 188 ++++++++++++++++++++++++++++++++
>  t/t7600-merge.sh                |   2 +-
>  xdiff-interface.c               |  12 ++
>  xdiff-interface.h               |   1 +
>  13 files changed, 431 insertions(+), 151 deletions(-)
>
>
> base-commit: b15384c06f77bc2d34d0d3623a8a58218313a561
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v7
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v7
> Pull-Request: https://github.com/git/git/pull/2234
>
> Range-diff vs v6:
>
>  1:  cd9c64ba60 ! 1:  284075600a stash: add --ours-label, --theirs-label, --base-label for apply
>      @@ Documentation/git-stash.adoc: git stash list [<log-options>]
>       -git stash apply [--index] [-q | --quiet] [<stash>]
>       +git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
>        git stash branch <branchname> [<stash>]
>      - git stash [push [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
>      + git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
>        	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
>       @@ Documentation/git-stash.adoc: the index's ones. However, this can fail, when you have conflicts
>        (which are stored in the index, where you therefore can no longer
>  2:  d572c4bb7d = 2:  64261e3cb6 sequencer: allow create_autostash to run silently
>  3:  80a98116fc = 3:  c0d6b4b4c0 sequencer: teach autostash apply to take optional conflict marker labels
>  4:  7ecb0835b7 ! 4:  1c29e19971 checkout: -m (--merge) uses autostash when switching branches
>      @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
>       -					0, 0);
>       -			init_ui_merge_options(&o, the_repository);
>       -			o.verbosity = 0;
>      --			work = write_in_core_index_as_tree(the_repository);
>      +-			work = write_in_core_index_as_tree(the_repository,
>      +-							   the_repository->index);
>       -
>       -			ret = reset_tree(new_tree,
>       -					 opts, 1,
>      @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
>       +	git reset --hard
>       +'
>       +
>      ++test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
>      ++	git checkout -f main &&
>      ++	git reset --hard &&
>      ++	git clean -f &&
>      ++
>      ++	git checkout -b nonoverlap_base &&
>      ++	fill a b c d >file &&
>      ++	git add file &&
>      ++	git commit -m "add file" &&
>      ++
>      ++	git checkout -b nonoverlap_child &&
>      ++	fill a b c INSERTED d >file &&
>      ++	git commit -a -m "insert line near end of file" &&
>      ++
>      ++	fill DIRTY a b c INSERTED d >file &&
>      ++
>      ++	git checkout -m nonoverlap_base 2>stderr &&
>      ++	test_grep "Applied autostash" stderr &&
>      ++	test_grep ! "resulted in conflicts" stderr &&
>      ++
>      ++	fill DIRTY a b c d >expect &&
>      ++	test_cmp expect file &&
>      ++
>      ++	git checkout -f main &&
>      ++	git branch -D nonoverlap_base &&
>      ++	git branch -D nonoverlap_child
>      ++'
>      ++
>       +test_expect_success 'checkout -m -b skips stash with dirty tree' '
>       +	git checkout -f main &&
>       +	git clean -f &&

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Thanks for an update.  Above the list of the commits, it would be
> helpful to give a summary of the overall goal of the topic (which
> typically stays more or less the same during the life of the topic)
> and the highlights of the changes since the previous iteration
> (which authors often accumulate, so that in a cover letter for v7,
> there will be 6 such summaries), if you are sending a cover letter.

I'm not exactly sure how to do that with GitGitGadget.

Isn't that what the commit message of the only non-preperatory commit is
here?


Harald

[PATCH v8 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Harald Nordgren (4):
  stash: add --ours-label, --theirs-label, --base-label for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  33 +++---
 builtin/checkout.c              | 138 ++++++++++------------
 builtin/stash.c                 |  32 ++++--
 sequencer.c                     |  67 ++++++++---
 sequencer.h                     |   4 +
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  37 ++++++
 t/t7201-co.sh                   | 195 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 14 files changed, 463 insertions(+), 157 deletions(-)


base-commit: b15384c06f77bc2d34d0d3623a8a58218313a561
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v8
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v8
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v7:

 1:  284075600a ! 1:  8fcf377820 stash: add --ours-label, --theirs-label, --base-label for apply
     @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
      +		echo upstream >file &&
      +		git add file &&
      +		git commit -m upstream &&
     -+		test_must_fail git stash apply --ours-label=UP --theirs-label=STASH &&
     -+		grep "^<<<<<<< UP" file &&
     -+		grep "^>>>>>>> STASH" file
     ++		test_must_fail git -c merge.conflictStyle=diff3 stash apply --ours-label=UP --theirs-label=STASH &&
     ++		test_grep "^<<<<<<< UP" file &&
     ++		test_grep "^||||||| Stash base" file &&
     ++		test_grep "^>>>>>>> STASH" file
     ++	)
     ++'
     ++
     ++test_expect_success 'apply with empty conflict labels' '
     ++	git init empty_labels &&
     ++	(
     ++		cd empty_labels &&
     ++		echo base >file &&
     ++		git add file &&
     ++		git commit -m base &&
     ++		echo stashed >file &&
     ++		git stash push -m "stashed" &&
     ++		echo upstream >file &&
     ++		git add file &&
     ++		git commit -m upstream &&
     ++		test_must_fail git stash apply --ours-label= --theirs-label= &&
     ++		test_grep "^<<<<<<<$" file &&
     ++		test_grep "^>>>>>>>$" file
      +	)
      +'
      +
       test_expect_success 'stash create reports a locked index' '
       	test_when_finished "rm -rf repo" &&
       	git init repo &&
     +
     + ## xdiff/xmerge.c ##
     +@@ xdiff/xmerge.c: static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
     + 			      int size, int i, int style,
     + 			      xdmerge_t *m, char *dest, int marker_size)
     + {
     +-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
     +-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
     +-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
     ++	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
     ++	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
     ++	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
     + 	int needs_cr = is_cr_needed(xe1, xe2, m);
     + 
     + 	if (marker_size <= 0)
 2:  64261e3cb6 = 2:  86cf68d024 sequencer: allow create_autostash to run silently
 3:  c0d6b4b4c0 ! 3:  78300e0e9a sequencer: teach autostash apply to take optional conflict marker labels
     @@ sequencer.c: void create_autostash_ref_silent(struct repository *r, const char *
       
      -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
      +static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor)
     ++				    const char *label_ours, const char *label_theirs,
     ++				    const char *label_base)
       {
       	struct child_process child = CHILD_PROCESS_INIT;
       	int ret = 0;
     @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
       		child.no_stderr = 1;
       		strvec_push(&child.args, "stash");
       		strvec_push(&child.args, "apply");
     -+		if (label1)
     -+			strvec_pushf(&child.args, "--ours-label=%s", label1);
     -+		if (label2)
     -+			strvec_pushf(&child.args, "--theirs-label=%s", label2);
     -+		if (label_ancestor)
     -+			strvec_pushf(&child.args, "--base-label=%s", label_ancestor);
     ++		if (label_ours)
     ++			strvec_pushf(&child.args, "--ours-label=%s", label_ours);
     ++		if (label_theirs)
     ++			strvec_pushf(&child.args, "--theirs-label=%s", label_theirs);
     ++		if (label_base)
     ++			strvec_pushf(&child.args, "--base-label=%s", label_base);
       		strvec_push(&child.args, stash_oid);
       		ret = run_command(&child);
       	}
     @@ sequencer.c: int apply_autostash(const char *path)
       static int apply_save_autostash_ref(struct repository *r, const char *refname,
      -				    int attempt_apply)
      +				    int attempt_apply,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor)
     ++				    const char *label_ours, const char *label_theirs,
     ++				    const char *label_base)
       {
       	struct object_id stash_oid;
       	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
     @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
       	oid_to_hex_r(stash_oid_hex, &stash_oid);
      -	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
      +	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
     -+				       label1, label2, label_ancestor);
     ++				       label_ours, label_theirs, label_base);
       
       	refs_delete_ref(get_main_ref_store(r), "", refname,
       			&stash_oid, REF_NO_DEREF);
     @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
      +}
      +
      +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor)
     ++				    const char *label_ours, const char *label_theirs,
     ++				    const char *label_base)
      +{
      +	return apply_save_autostash_ref(r, refname, 1,
     -+					label1, label2, label_ancestor);
     ++					label_ours, label_theirs, label_base);
       }
       
       static int checkout_onto(struct repository *r, struct replay_opts *opts,
     @@ sequencer.h: int save_autostash_ref(struct repository *r, const char *refname);
       int apply_autostash_oid(const char *stash_oid);
       int apply_autostash_ref(struct repository *r, const char *refname);
      +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     -+				    const char *label1, const char *label2,
     -+				    const char *label_ancestor);
     ++				    const char *label_ours, const char *label_theirs,
     ++				    const char *label_base);
       
       #define SUMMARY_INITIAL_COMMIT   (1 << 0)
       #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
 4:  1c29e19971 ! 4:  aa18313362 checkout: -m (--merge) uses autostash when switching branches
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
      +When the `--merge` (`-m`) option is in effect and the locally
      +modified files overlap with files that need to be updated by the
      +branch switch, the changes are stashed and reapplied after the
     -+switch.  If the stash application results in conflicts, they are not
     -+resolved and the stash is saved to the stash list:
     ++switch.  If this process results in conflicts, a stash entry is saved
     ++and made available in `git stash list`:
       
       ------------
       $ git checkout -m mytopic
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
      
       ## Documentation/git-switch.adoc ##
      @@ Documentation/git-switch.adoc: variable.
     - 	If you have local modifications to one or more files that are
     - 	different between the current branch and the branch to which
     - 	you are switching, the command refuses to switch branches in
     + 
     + `-m`::
     + `--merge`::
     +-	If you have local modifications to one or more files that are
     +-	different between the current branch and the branch to which
     +-	you are switching, the command refuses to switch branches in
      -	order to preserve your modifications in context.  However,
      -	with this option, a three-way merge between the current
      -	branch, your working tree contents, and the new branch is
     @@ Documentation/git-switch.adoc: variable.
      -paths are left unmerged, and you need to resolve the conflicts
      -and mark the resolved paths with `git add` (or `git rm` if the merge
      -should result in deletion of the path).
     -+	order to preserve your modifications in context.  With this
     -+	option, the conflicting local changes are automatically
     -+	stashed before the switch and reapplied afterwards.  If the
     -+	local changes do not overlap with the differences between
     -+	branches, the switch proceeds without stashing.  If
     -+	reapplying the stash results in conflicts, the entry is
     -+	saved to the stash list.  Resolve the conflicts and run
     -+	`git stash drop` when done, or clear the working tree
     -+	(e.g. with `git reset --hard`) before running `git stash pop`
     -+	later to re-apply your changes.
     ++	If you have local modifications to one or more files that
     ++	are different between the current branch and the branch to
     ++	which you are switching, the command normally refuses to
     ++	switch branches in order to preserve your modifications in
     ++	context.  However, with this option, the conflicting local
     ++	changes are automatically stashed before the switch and
     ++	reapplied afterwards.  If the local changes do not overlap
     ++	with the differences between branches, the switch proceeds
     ++	without stashing.  If reapplying the stash results in
     ++	conflicts, the entry is saved to the stash list.  Resolve
     ++	the conflicts and run `git stash drop` when done, or clear
     ++	the working tree (e.g. with `git reset --hard`) before
     ++	running `git stash pop` later to re-apply your changes.
       
       `--conflict=<style>`::
       	The same as `--merge` option above, but changes the way the
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	git clean -f &&
      +
      +	fill 0 x y z >same &&
     ++	git stash list >stash-before &&
      +	git checkout -m side >actual 2>&1 &&
      +	test_grep ! "Created autostash" actual &&
     ++	git stash list >stash-after &&
     ++	test_cmp stash-before stash-after &&
      +	fill 0 x y z >expect &&
      +	test_cmp expect same
      +'
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +
      +	fill DIRTY a b c INSERTED d >file &&
      +
     ++	git stash list >stash-before &&
      +	git checkout -m nonoverlap_base 2>stderr &&
      +	test_grep "Applied autostash" stderr &&
      +	test_grep ! "resulted in conflicts" stderr &&
      +
     ++	git stash list >stash-after &&
     ++	test_cmp stash-before stash-after &&
     ++
      +	fill DIRTY a b c d >expect &&
      +	test_cmp expect file &&
      +

-- 
gitgitgadget

[PATCH v8 1/4] stash: add --ours-label, --theirs-label, --base-label for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              |  2 +-
 t/t3903-stash.sh             | 37 ++++++++++++++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..6829ba1140 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--ours-label=<label>`::
+`--theirs-label=<label>`::
+`--base-label=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--base-label` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..54bcb6ac73 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..d4e4e4d7b6 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,43 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		echo base >file &&
+		git add file &&
+		git commit -m base &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		echo upstream >file &&
+		git add file &&
+		git commit -m upstream &&
+		test_must_fail git -c merge.conflictStyle=diff3 stash apply --ours-label=UP --theirs-label=STASH &&
+		test_grep "^<<<<<<< UP" file &&
+		test_grep "^||||||| Stash base" file &&
+		test_grep "^>>>>>>> STASH" file
+	)
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git init empty_labels &&
+	(
+		cd empty_labels &&
+		echo base >file &&
+		git add file &&
+		git commit -m base &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		echo upstream >file &&
+		git add file &&
+		git commit -m upstream &&
+		test_must_fail git stash apply --ours-label= --theirs-label= &&
+		test_grep "^<<<<<<<$" file &&
+		test_grep "^>>>>>>>$" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

Re: [PATCH v8 1/4] stash: add --ours-label, --theirs-label, --base-label for apply

[Phillip Wood]

Hi Harald

On 09/04/2026 20:17, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Allow callers of "git stash apply" to pass custom labels for conflict
> markers instead of the default "Updated upstream" and "Stashed changes".
> Document the new options and add a test.

Sounds sensible and the documentation looks good.

> diff --git a/builtin/stash.c b/builtin/stash.c
> index 0d27b2fb1f..54bcb6ac73 100644
> --- a/builtin/stash.c
> +++ b/builtin/stash.c
> @@ -44,7 +44,7 @@
>   #define BUILTIN_STASH_POP_USAGE \
>   	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
>   #define BUILTIN_STASH_APPLY_USAGE \
> -	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
> +	N_("git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]")
>   #define BUILTIN_STASH_BRANCH_USAGE \
>   	N_("git stash branch <branchname> [<stash>]")
>   #define BUILTIN_STASH_STORE_USAGE \

This patch seems to be missing the implementation of these new options. 
Before submitting a patch series I find it is very helpful to run

     git rebase --keep-base -x make -x 'cd t && prove -j6 <tests that I 
think might fail>'

to catch any mistakes.

> diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
> index 70879941c2..d4e4e4d7b6 100755
> --- a/t/t3903-stash.sh
> +++ b/t/t3903-stash.sh
> @@ -1666,6 +1666,43 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
>   	)
>   '
>   
> +test_expect_success 'apply with custom conflict labels' '
> +	git init conflict_labels &&

Why do we need to create a new repository just to stash some changes?

> +	(
> +		cd conflict_labels &&
> +		echo base >file &&
> +		git add file &&
> +		git commit -m base &&

We have a helper test_commit() for creating commits (it is documented in 
t/test-lib-functions.sh)

> +		echo stashed >file &&
> +		git stash push -m "stashed" &&
> +		echo upstream >file &&
> +		git add file &&
> +		git commit -m upstream &&
> +		test_must_fail git -c merge.conflictStyle=diff3 stash apply --ours-label=UP --theirs-label=STASH &&
> +		test_grep "^<<<<<<< UP" file &&
> +		test_grep "^||||||| Stash base" file &&
> +		test_grep "^>>>>>>> STASH" file

Hurray for the use of test_grep here!

> +	)
> +'
> +
> +test_expect_success 'apply with empty conflict labels' '

Why do we want to support empty labels rather than making them an error?

Thanks

Phillip

> +	git init empty_labels &&
> +	(
> +		cd empty_labels &&
> +		echo base >file &&
> +		git add file &&
> +		git commit -m base &&
> +		echo stashed >file &&
> +		git stash push -m "stashed" &&
> +		echo upstream >file &&
> +		git add file &&
> +		git commit -m upstream &&
> +		test_must_fail git stash apply --ours-label= --theirs-label= &&
> +		test_grep "^<<<<<<<$" file &&
> +		test_grep "^>>>>>>>$" file
> +	)
> +'
> +
>   test_expect_success 'stash create reports a locked index' '
>   	test_when_finished "rm -rf repo" &&
>   	git init repo &&
> diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
> index 29dad98c49..659ad4ec97 100644
> --- a/xdiff/xmerge.c
> +++ b/xdiff/xmerge.c
> @@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
>   			      int size, int i, int style,
>   			      xdmerge_t *m, char *dest, int marker_size)
>   {
> -	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
> -	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
> -	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
> +	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
> +	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
> +	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
>   	int needs_cr = is_cr_needed(xe1, xe2, m);
>   
>   	if (marker_size <= 0)

Re: [PATCH v8 1/4] stash: add --ours-label, --theirs-label, --base-label for apply

[Junio C Hamano]

Phillip Wood <phillip.wood123@gmail.com> writes:

>> +test_expect_success 'apply with empty conflict labels' '
>
> Why do we want to support empty labels rather than making them an error?

Why not?

There are applications that do not require, and prefer to have more
stable output that will not be affected by UI updates to improve
human-user experience.  Even though rerere database is not populated
with the facility this patch implements, we can see in

    $ grep -C2 -e '^\([<=>]\)\1\{6,\}$' .git/rr-cache/*/preimage*

how having labels make the output more noisy, and more importantly,
will make it misleading given how rerere is designed to work,
treating the same merge conflicts in both directions equivalents.
It is not a huge stretch of imagination that our users will find
similar needs, I would imagine.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> This patch seems to be missing the implementation of these new options. 
> Before submitting a patch series I find it is very helpful to run
> 
>      git rebase --keep-base -x make -x 'cd t && prove -j6 <tests that I 
> think might fail>'
> 
> to catch any mistakes.

Wow, that command is so powerful! Thanks for sharing that!

Will shift that definition to an earlier commit in my set.

> Why do we need to create a new repository just to stash some changes?

Isn't it good to do it in isolation, for when the test and/or its cleanup
fails. I tried to change it now, but it's not trivial, I quickly broke a
lot of subsequent tests.

> We have a helper test_commit() for creating commits (it is documented in 
> t/test-lib-functions.sh)

Thanks, will update!


Harald

[PATCH v8 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.  Use stderr for
the message when not silent.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 15 +++++++++++----
 sequencer.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..e500a94a59 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      int silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4702,7 +4703,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4716,17 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, 0);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, 0);
+}
+
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, 1);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..570f804457 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -230,6 +230,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

Re: [PATCH v8 2/4] sequencer: allow create_autostash to run silently

[Phillip Wood]

Hi Harald

On 09/04/2026 20:17, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add a silent parameter to create_autostash_internal and introduce
> create_autostash_ref_silent so that callers can create an autostash
> without printing the "Created autostash" message.  Use stderr for
> the message when not silent.

Why do we want to change where the message is printed? It is not 
necessarily a bad idea but it would be helpful to explain why we want 
that particular change.

> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>   sequencer.c | 15 +++++++++++----
>   sequencer.h |  1 +
>   2 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/sequencer.c b/sequencer.c
> index b7d8dca47f..e500a94a59 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4657,7 +4657,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
>   
>   static void create_autostash_internal(struct repository *r,
>   				      const char *path,
> -				      const char *refname)
> +				      const char *refname,
> +				      int silent)

This could be a "bool" and the users could pass "true" and "false". 
Apart from that this looks good.

Thanks

Phillip

>   {
>   	struct strbuf buf = STRBUF_INIT;
>   	struct lock_file lock_file = LOCK_INIT;
> @@ -4702,7 +4703,8 @@ static void create_autostash_internal(struct repository *r,
>   					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
>   		}
>   
> -		printf(_("Created autostash: %s\n"), buf.buf);
> +		if (!silent)
> +			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
>   		if (reset_head(r, &ropts) < 0)
>   			die(_("could not reset --hard"));
>   		discard_index(r->index);
> @@ -4714,12 +4716,17 @@ static void create_autostash_internal(struct repository *r,
>   
>   void create_autostash(struct repository *r, const char *path)
>   {
> -	create_autostash_internal(r, path, NULL);
> +	create_autostash_internal(r, path, NULL, 0);
>   }
>   
>   void create_autostash_ref(struct repository *r, const char *refname)
>   {
> -	create_autostash_internal(r, NULL, refname);
> +	create_autostash_internal(r, NULL, refname, 0);
> +}
> +
> +void create_autostash_ref_silent(struct repository *r, const char *refname)
> +{
> +	create_autostash_internal(r, NULL, refname, 1);
>   }
>   
>   static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
> diff --git a/sequencer.h b/sequencer.h
> index a6fa670c7c..570f804457 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -230,6 +230,7 @@ void commit_post_rewrite(struct repository *r,
>   
>   void create_autostash(struct repository *r, const char *path);
>   void create_autostash_ref(struct repository *r, const char *refname);
> +void create_autostash_ref_silent(struct repository *r, const char *refname);
>   int save_autostash(const char *path);
>   int save_autostash_ref(struct repository *r, const char *refname);
>   int apply_autostash(const char *path);

Re: [PATCH v8 2/4] sequencer: allow create_autostash to run silently

[Junio C Hamano]

Phillip Wood <phillip.wood123@gmail.com> writes:

>> Add a silent parameter to create_autostash_internal and introduce
>> create_autostash_ref_silent so that callers can create an autostash
>> without printing the "Created autostash" message.  Use stderr for
>> the message when not silent.
>
> Why do we want to change where the message is printed? It is not 
> necessarily a bad idea but it would be helpful to explain why we want 
> that particular change.

Yes, this is a great point.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Why do we want to change where the message is printed? It is not 
> necessarily a bad idea but it would be helpful to explain why we want 
> that particular change.

No good reason, and I will revert it.

> This could be a "bool" and the users could pass "true" and "false". 

Agreed.


Harald

[PATCH v8 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label1, label2, and label_ancestor parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --ours-label/--theirs-label/--base-label".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 34 +++++++++++++++++++++++++++-------
 sequencer.h |  3 +++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index e500a94a59..e28d30ff7b 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4729,7 +4729,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, 1);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4740,6 +4742,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--ours-label=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--theirs-label=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--base-label=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4784,7 +4792,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4803,11 +4812,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4823,7 +4834,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4833,12 +4845,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 570f804457..2c4ff17c4e 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -236,6 +236,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

Re: [PATCH v8 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Phillip Wood]

Hi Harald

On 09/04/2026 20:17, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add label1, label2, and label_ancestor parameters to the autostash
> apply machinery so callers can pass custom conflict marker labels
> through to "git stash apply --ours-label/--theirs-label/--base-label".
> Introduce apply_autostash_ref_with_labels() for callers that want
> to pass labels.

This looks good. In the future we could use this to set some better 
labels for "git rebase --autostash" but that does not need to be part of 
this series.

I'll leave it there for today and take a look at the last patch next 
week. It would be a good idea to wait a few days to see if anyone else 
has any comments before sending a new version.

Thanks

Phillip

> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>   sequencer.c | 34 +++++++++++++++++++++++++++-------
>   sequencer.h |  3 +++
>   2 files changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/sequencer.c b/sequencer.c
> index e500a94a59..e28d30ff7b 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4729,7 +4729,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
>   	create_autostash_internal(r, NULL, refname, 1);
>   }
>   
> -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
> +static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
> +				    const char *label_ours, const char *label_theirs,
> +				    const char *label_base)
>   {
>   	struct child_process child = CHILD_PROCESS_INIT;
>   	int ret = 0;
> @@ -4740,6 +4742,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
>   		child.no_stderr = 1;
>   		strvec_push(&child.args, "stash");
>   		strvec_push(&child.args, "apply");
> +		if (label_ours)
> +			strvec_pushf(&child.args, "--ours-label=%s", label_ours);
> +		if (label_theirs)
> +			strvec_pushf(&child.args, "--theirs-label=%s", label_theirs);
> +		if (label_base)
> +			strvec_pushf(&child.args, "--base-label=%s", label_base);
>   		strvec_push(&child.args, stash_oid);
>   		ret = run_command(&child);
>   	}
> @@ -4784,7 +4792,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
>   	}
>   	strbuf_trim(&stash_oid);
>   
> -	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
> +	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
> +				      NULL, NULL, NULL);
>   
>   	unlink(path);
>   	strbuf_release(&stash_oid);
> @@ -4803,11 +4812,13 @@ int apply_autostash(const char *path)
>   
>   int apply_autostash_oid(const char *stash_oid)
>   {
> -	return apply_save_autostash_oid(stash_oid, 1);
> +	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
>   }
>   
>   static int apply_save_autostash_ref(struct repository *r, const char *refname,
> -				    int attempt_apply)
> +				    int attempt_apply,
> +				    const char *label_ours, const char *label_theirs,
> +				    const char *label_base)
>   {
>   	struct object_id stash_oid;
>   	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
> @@ -4823,7 +4834,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
>   		return error(_("autostash reference is a symref"));
>   
>   	oid_to_hex_r(stash_oid_hex, &stash_oid);
> -	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
> +	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
> +				       label_ours, label_theirs, label_base);
>   
>   	refs_delete_ref(get_main_ref_store(r), "", refname,
>   			&stash_oid, REF_NO_DEREF);
> @@ -4833,12 +4845,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
>   
>   int save_autostash_ref(struct repository *r, const char *refname)
>   {
> -	return apply_save_autostash_ref(r, refname, 0);
> +	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
>   }
>   
>   int apply_autostash_ref(struct repository *r, const char *refname)
>   {
> -	return apply_save_autostash_ref(r, refname, 1);
> +	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
> +}
> +
> +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
> +				    const char *label_ours, const char *label_theirs,
> +				    const char *label_base)
> +{
> +	return apply_save_autostash_ref(r, refname, 1,
> +					label_ours, label_theirs, label_base);
>   }
>   
>   static int checkout_onto(struct repository *r, struct replay_opts *opts,
> diff --git a/sequencer.h b/sequencer.h
> index 570f804457..2c4ff17c4e 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -236,6 +236,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
>   int apply_autostash(const char *path);
>   int apply_autostash_oid(const char *stash_oid);
>   int apply_autostash_ref(struct repository *r, const char *refname);
> +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
> +				    const char *label_ours, const char *label_theirs,
> +				    const char *label_base);
>   
>   #define SUMMARY_INITIAL_COMMIT   (1 << 0)
>   #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)

Re: [PATCH v8 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Junio C Hamano]

Phillip Wood <phillip.wood123@gmail.com> writes:

> Hi Harald
>
> On 09/04/2026 20:17, Harald Nordgren via GitGitGadget wrote:
>> From: Harald Nordgren <haraldnordgren@gmail.com>
>> 
>> Add label1, label2, and label_ancestor parameters to the autostash

Sorry, I just noticed that these three should have been updated when
the actual parameters were renamed.

>> apply machinery so callers can pass custom conflict marker labels
>> through to "git stash apply --ours-label/--theirs-label/--base-label".
>> Introduce apply_autostash_ref_with_labels() for callers that want
>> to pass labels.
>
> This looks good. In the future we could use this to set some better 
> labels for "git rebase --autostash" but that does not need to be part of 
> this series.

Great.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Sorry, I just noticed that these three should have been updated when
> the actual parameters were renamed.

Good point!

I also switched it to prefix naming label_*, which makes more sense to me.


Harald

[PATCH v8 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-switch.adoc   |  33 +++---
 builtin/checkout.c              | 138 ++++++++++------------
 builtin/stash.c                 |  30 ++++-
 sequencer.c                     |  18 ++-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 195 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 10 files changed, 370 insertions(+), 141 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..283bec2518 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
+			rollback_lock_file(&lock_file);
+			return 1;
 		}
 	}
 
@@ -1166,6 +1099,9 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	const char *stash_label_ancestor = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1203,10 +1139,31 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_ancestor = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_ancestor = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret && opts->merge) {
+			create_autostash_ref_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH");
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_ancestor);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
 			return ret;
 		}
 	}
@@ -1216,8 +1173,29 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
+				       new_branch_info->name, "local",
+				       stash_label_ancestor);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
 
 	return ret || writeout_error;
 }
diff --git a/builtin/stash.c b/builtin/stash.c
index 54bcb6ac73..4c8e8ab59a 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label1, const char *label2,
+				      const char *label_ancestor)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label1 ? label1 : "Updated upstream";
+	o.branch2 = label2 ? label2 : "Stashed changes";
+	o.ancestor = label_ancestor ? label_ancestor : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label1 = NULL, *label2 = NULL, *label_ancestor = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "ours-label", &label1, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "theirs-label", &label2, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "base-label", &label_ancestor, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label1, label2, label_ancestor);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/sequencer.c b/sequencer.c
index e28d30ff7b..340ca4c9ce 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4766,15 +4766,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..8f02a664f4 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,201 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git stash list >stash-before &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git stash list >stash-before &&
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v8 4/4] checkout: -m (--merge) uses autostash when switching branches

[Chris Torek]

On Thu, Apr 9, 2026 at 12:18 PM Harald Nordgren via GitGitGadget
<gitgitgadget@gmail.com> wrote:
> ... If reapplying causes conflicts, the stash is
> kept and the user is told they can resolve and run "git stash drop",
> or run "git reset --hard" and later "git stash pop" to recover their
> changes.

I might suggest that this should recommend "git stash pop --index"
(either always, or if the stashed index differs from the stash's parent).

Chris

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> I might suggest that this should recommend "git stash pop --index"
> (either always, or if the stashed index differs from the stash's parent).

Interesting! This is a new option that I've never seen before.



Harald

[PATCH v9 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Harald Nordgren (4):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  33 +++---
 builtin/checkout.c              | 138 ++++++++++------------
 builtin/stash.c                 |  32 ++++--
 sequencer.c                     |  67 ++++++++---
 sequencer.h                     |   4 +
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  29 +++++
 t/t7201-co.sh                   | 195 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 14 files changed, 455 insertions(+), 157 deletions(-)


base-commit: cd412a49627774a14b3e49237109a77bd3ea70c0
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v9
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v9
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v8:

 1:  8fcf377820 ! 1:  5d5dc1f60e stash: add --ours-label, --theirs-label, --base-label for apply
     @@ Metadata
      Author: Harald Nordgren <haraldnordgren@gmail.com>
      
       ## Commit message ##
     -    stash: add --ours-label, --theirs-label, --base-label for apply
     +    stash: add --label-ours, --label-theirs, --label-base for apply
      
          Allow callers of "git stash apply" to pass custom labels for conflict
          markers instead of the default "Updated upstream" and "Stashed changes".
     @@ Documentation/git-stash.adoc: git stash list [<log-options>]
       git stash drop [-q | --quiet] [<stash>]
       git stash pop [--index] [-q | --quiet] [<stash>]
      -git stash apply [--index] [-q | --quiet] [<stash>]
     -+git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]
     ++git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
       git stash branch <branchname> [<stash>]
       git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
       	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
     @@ Documentation/git-stash.adoc: the index's ones. However, this can fail, when you
       (which are stored in the index, where you therefore can no longer
       apply the changes as they were originally).
       
     -+`--ours-label=<label>`::
     -+`--theirs-label=<label>`::
     -+`--base-label=<label>`::
     ++`--label-ours=<label>`::
     ++`--label-theirs=<label>`::
     ++`--label-base=<label>`::
      +	These options are only valid for the `apply` command.
      ++
      +Use the given labels in conflict markers instead of the default
      +"Updated upstream", "Stashed changes", and "Stash base".
     -+`--base-label` only has an effect with merge.conflictStyle=diff3.
     ++`--label-base` only has an effect with merge.conflictStyle=diff3.
      +
       `-k`::
       `--keep-index`::
     @@ builtin/stash.c
       	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
       #define BUILTIN_STASH_APPLY_USAGE \
      -	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
     -+	N_("git stash apply [--index] [-q | --quiet] [--ours-label=<label>] [--theirs-label=<label>] [--base-label=<label>] [<stash>]")
     ++	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
       #define BUILTIN_STASH_BRANCH_USAGE \
       	N_("git stash branch <branchname> [<stash>]")
       #define BUILTIN_STASH_STORE_USAGE \
     +@@ builtin/stash.c: static void unstage_changes_unless_new(struct object_id *orig_tree)
     + 		die(_("could not write index"));
     + }
     + 
     +-static int do_apply_stash(const char *prefix, struct stash_info *info,
     +-			  int index, int quiet)
     ++static int do_apply_stash_with_labels(const char *prefix,
     ++				      struct stash_info *info,
     ++				      int index, int quiet,
     ++				      const char *label_ours, const char *label_theirs,
     ++				      const char *label_base)
     + {
     + 	int clean, ret;
     + 	int has_index = index;
     +@@ builtin/stash.c: static int do_apply_stash(const char *prefix, struct stash_info *info,
     + 
     + 	init_ui_merge_options(&o, the_repository);
     + 
     +-	o.branch1 = "Updated upstream";
     +-	o.branch2 = "Stashed changes";
     +-	o.ancestor = "Stash base";
     ++	o.branch1 = label_ours ? label_ours : "Updated upstream";
     ++	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
     ++	o.ancestor = label_base ? label_base : "Stash base";
     + 
     + 	if (oideq(&info->b_tree, &c_tree))
     + 		o.branch1 = "Version stash was based on";
     +@@ builtin/stash.c: restore_untracked:
     + 	return ret;
     + }
     + 
     ++static int do_apply_stash(const char *prefix, struct stash_info *info,
     ++			  int index, int quiet)
     ++{
     ++	return do_apply_stash_with_labels(prefix, info, index, quiet,
     ++					  NULL, NULL, NULL);
     ++}
     ++
     + static int apply_stash(int argc, const char **argv, const char *prefix,
     + 		       struct repository *repo UNUSED)
     + {
     + 	int ret = -1;
     + 	int quiet = 0;
     + 	int index = use_index;
     ++	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
     + 	struct stash_info info = STASH_INFO_INIT;
     + 	struct option options[] = {
     + 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
     + 		OPT_BOOL(0, "index", &index,
     + 			 N_("attempt to recreate the index")),
     ++		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
     ++			   N_("label for the upstream side in conflict markers")),
     ++		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
     ++			   N_("label for the stashed side in conflict markers")),
     ++		OPT_STRING(0, "label-base", &label_base, N_("label"),
     ++			   N_("label for the base in diff3 conflict markers")),
     + 		OPT_END()
     + 	};
     + 
     +@@ builtin/stash.c: static int apply_stash(int argc, const char **argv, const char *prefix,
     + 	if (get_stash_info(&info, argc, argv))
     + 		goto cleanup;
     + 
     +-	ret = do_apply_stash(prefix, &info, index, quiet);
     ++	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
     ++					 label_ours, label_theirs, label_base);
     + cleanup:
     + 	free_stash_info(&info);
     + 	return ret;
      
       ## t/t3903-stash.sh ##
      @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit conflicts' '
     @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
      +	git init conflict_labels &&
      +	(
      +		cd conflict_labels &&
     -+		echo base >file &&
     -+		git add file &&
     -+		git commit -m base &&
     ++		test_commit base file &&
      +		echo stashed >file &&
      +		git stash push -m "stashed" &&
     -+		echo upstream >file &&
     -+		git add file &&
     -+		git commit -m upstream &&
     -+		test_must_fail git -c merge.conflictStyle=diff3 stash apply --ours-label=UP --theirs-label=STASH &&
     ++		test_commit upstream file &&
     ++		test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
      +		test_grep "^<<<<<<< UP" file &&
      +		test_grep "^||||||| Stash base" file &&
      +		test_grep "^>>>>>>> STASH" file
     @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
      +	git init empty_labels &&
      +	(
      +		cd empty_labels &&
     -+		echo base >file &&
     -+		git add file &&
     -+		git commit -m base &&
     ++		test_commit base file &&
      +		echo stashed >file &&
      +		git stash push -m "stashed" &&
     -+		echo upstream >file &&
     -+		git add file &&
     -+		git commit -m upstream &&
     -+		test_must_fail git stash apply --ours-label= --theirs-label= &&
     ++		test_commit upstream file &&
     ++		test_must_fail git stash apply --label-ours= --label-theirs= &&
      +		test_grep "^<<<<<<<$" file &&
      +		test_grep "^>>>>>>>$" file
      +	)
 2:  86cf68d024 ! 2:  a1fa04a965 sequencer: allow create_autostash to run silently
     @@ Commit message
      
          Add a silent parameter to create_autostash_internal and introduce
          create_autostash_ref_silent so that callers can create an autostash
     -    without printing the "Created autostash" message.  Use stderr for
     -    the message when not silent.
     +    without printing the "Created autostash" message.
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     @@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list,
       				      const char *path,
      -				      const char *refname)
      +				      const char *refname,
     -+				      int silent)
     ++				      bool silent)
       {
       	struct strbuf buf = STRBUF_INIT;
       	struct lock_file lock_file = LOCK_INIT;
     @@ sequencer.c: static void create_autostash_internal(struct repository *r,
       
      -		printf(_("Created autostash: %s\n"), buf.buf);
      +		if (!silent)
     -+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
     ++			printf(_("Created autostash: %s\n"), buf.buf);
       		if (reset_head(r, &ropts) < 0)
       			die(_("could not reset --hard"));
       		discard_index(r->index);
     @@ sequencer.c: static void create_autostash_internal(struct repository *r,
       void create_autostash(struct repository *r, const char *path)
       {
      -	create_autostash_internal(r, path, NULL);
     -+	create_autostash_internal(r, path, NULL, 0);
     ++	create_autostash_internal(r, path, NULL, false);
       }
       
       void create_autostash_ref(struct repository *r, const char *refname)
       {
      -	create_autostash_internal(r, NULL, refname);
     -+	create_autostash_internal(r, NULL, refname, 0);
     ++	create_autostash_internal(r, NULL, refname, false);
      +}
      +
      +void create_autostash_ref_silent(struct repository *r, const char *refname)
      +{
     -+	create_autostash_internal(r, NULL, refname, 1);
     ++	create_autostash_internal(r, NULL, refname, true);
       }
       
       static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 3:  78300e0e9a ! 3:  87216a633b sequencer: teach autostash apply to take optional conflict marker labels
     @@ Metadata
       ## Commit message ##
          sequencer: teach autostash apply to take optional conflict marker labels
      
     -    Add label1, label2, and label_ancestor parameters to the autostash
     +    Add label_ours, label_theirs, and label_base parameters to the autostash
          apply machinery so callers can pass custom conflict marker labels
     -    through to "git stash apply --ours-label/--theirs-label/--base-label".
     +    through to "git stash apply --label-ours/--label-theirs/--label-base".
          Introduce apply_autostash_ref_with_labels() for callers that want
          to pass labels.
      
     @@ Commit message
      
       ## sequencer.c ##
      @@ sequencer.c: void create_autostash_ref_silent(struct repository *r, const char *refname)
     - 	create_autostash_internal(r, NULL, refname, 1);
     + 	create_autostash_internal(r, NULL, refname, true);
       }
       
      -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
       		strvec_push(&child.args, "stash");
       		strvec_push(&child.args, "apply");
      +		if (label_ours)
     -+			strvec_pushf(&child.args, "--ours-label=%s", label_ours);
     ++			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
      +		if (label_theirs)
     -+			strvec_pushf(&child.args, "--theirs-label=%s", label_theirs);
     ++			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
      +		if (label_base)
     -+			strvec_pushf(&child.args, "--base-label=%s", label_base);
     ++			strvec_pushf(&child.args, "--label-base=%s", label_base);
       		strvec_push(&child.args, stash_oid);
       		ret = run_command(&child);
       	}
 4:  aa18313362 ! 4:  00e0b3196c checkout: -m (--merge) uses autostash when switching branches
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	int do_merge = 1;
      +	int created_autostash = 0;
      +	struct strbuf old_commit_shortname = STRBUF_INIT;
     -+	const char *stash_label_ancestor = NULL;
     ++	const char *stash_label_base = NULL;
       
       	trace2_cmd_mode("branch");
       
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	}
       
      +	if (old_branch_info.name)
     -+		stash_label_ancestor = old_branch_info.name;
     ++		stash_label_base = old_branch_info.name;
      +	else if (old_branch_info.commit) {
      +		strbuf_add_unique_abbrev(&old_commit_shortname,
      +					 &old_branch_info.commit->object.oid,
      +					 DEFAULT_ABBREV);
     -+		stash_label_ancestor = old_commit_shortname.buf;
     ++		stash_label_base = old_commit_shortname.buf;
      +	}
      +
       	if (do_merge) {
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +						       "CHECKOUT_AUTOSTASH",
      +						       new_branch_info->name,
      +						       "local",
     -+						       stash_label_ancestor);
     ++						       stash_label_base);
       			branch_info_release(&old_branch_info);
      +			strbuf_release(&old_commit_shortname);
       			return ret;
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +	}
      +	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
      +				       new_branch_info->name, "local",
     -+				       stash_label_ancestor);
     ++				       stash_label_base);
      +
      +	discard_index(the_repository->index);
      +	if (repo_read_index(the_repository) < 0)
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	return ret || writeout_error;
       }
      
     - ## builtin/stash.c ##
     -@@ builtin/stash.c: static void unstage_changes_unless_new(struct object_id *orig_tree)
     - 		die(_("could not write index"));
     - }
     - 
     --static int do_apply_stash(const char *prefix, struct stash_info *info,
     --			  int index, int quiet)
     -+static int do_apply_stash_with_labels(const char *prefix,
     -+				      struct stash_info *info,
     -+				      int index, int quiet,
     -+				      const char *label1, const char *label2,
     -+				      const char *label_ancestor)
     - {
     - 	int clean, ret;
     - 	int has_index = index;
     -@@ builtin/stash.c: static int do_apply_stash(const char *prefix, struct stash_info *info,
     - 
     - 	init_ui_merge_options(&o, the_repository);
     - 
     --	o.branch1 = "Updated upstream";
     --	o.branch2 = "Stashed changes";
     --	o.ancestor = "Stash base";
     -+	o.branch1 = label1 ? label1 : "Updated upstream";
     -+	o.branch2 = label2 ? label2 : "Stashed changes";
     -+	o.ancestor = label_ancestor ? label_ancestor : "Stash base";
     - 
     - 	if (oideq(&info->b_tree, &c_tree))
     - 		o.branch1 = "Version stash was based on";
     -@@ builtin/stash.c: restore_untracked:
     - 	return ret;
     - }
     - 
     -+static int do_apply_stash(const char *prefix, struct stash_info *info,
     -+			  int index, int quiet)
     -+{
     -+	return do_apply_stash_with_labels(prefix, info, index, quiet,
     -+					  NULL, NULL, NULL);
     -+}
     -+
     - static int apply_stash(int argc, const char **argv, const char *prefix,
     - 		       struct repository *repo UNUSED)
     - {
     - 	int ret = -1;
     - 	int quiet = 0;
     - 	int index = use_index;
     -+	const char *label1 = NULL, *label2 = NULL, *label_ancestor = NULL;
     - 	struct stash_info info = STASH_INFO_INIT;
     - 	struct option options[] = {
     - 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
     - 		OPT_BOOL(0, "index", &index,
     - 			 N_("attempt to recreate the index")),
     -+		OPT_STRING(0, "ours-label", &label1, N_("label"),
     -+			   N_("label for the upstream side in conflict markers")),
     -+		OPT_STRING(0, "theirs-label", &label2, N_("label"),
     -+			   N_("label for the stashed side in conflict markers")),
     -+		OPT_STRING(0, "base-label", &label_ancestor, N_("label"),
     -+			   N_("label for the base in diff3 conflict markers")),
     - 		OPT_END()
     - 	};
     - 
     -@@ builtin/stash.c: static int apply_stash(int argc, const char **argv, const char *prefix,
     - 	if (get_stash_info(&info, argc, argv))
     - 		goto cleanup;
     - 
     --	ret = do_apply_stash(prefix, &info, index, quiet);
     -+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
     -+					 label1, label2, label_ancestor);
     - cleanup:
     - 	free_stash_info(&info);
     - 	return ret;
     -
       ## sequencer.c ##
      @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
       		strvec_push(&store.args, stash_oid);

-- 
gitgitgadget

[PATCH v9 1/4] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 32 +++++++++++++++++++++++++-------
 t/t3903-stash.sh             | 29 +++++++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 67 insertions(+), 11 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..00314e2b13 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label_ours, const char *label_theirs,
+				      const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..00bcb1f802 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,35 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+		test_grep "^<<<<<<< UP" file &&
+		test_grep "^||||||| Stash base" file &&
+		test_grep "^>>>>>>> STASH" file
+	)
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git init empty_labels &&
+	(
+		cd empty_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git stash apply --label-ours= --label-theirs= &&
+		test_grep "^<<<<<<<$" file &&
+		test_grep "^>>>>>>>$" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

[PATCH v9 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 15 +++++++++++----
 sequencer.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..1197d7d8a0 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4702,7 +4703,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4716,17 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, false);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, false);
+}
+
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, true);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..570f804457 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -230,6 +230,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v9 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, and label_base parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --label-ours/--label-theirs/--label-base".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 34 +++++++++++++++++++++++++++-------
 sequencer.h |  3 +++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 1197d7d8a0..913be115f2 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4729,7 +4729,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, true);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4740,6 +4742,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4784,7 +4792,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4803,11 +4812,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4823,7 +4834,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4833,12 +4845,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 570f804457..2c4ff17c4e 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -236,6 +236,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v9 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-switch.adoc   |  33 +++---
 builtin/checkout.c              | 138 ++++++++++------------
 sequencer.c                     |  18 ++-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 195 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 9 files changed, 346 insertions(+), 135 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..52c84bbe84 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
+			rollback_lock_file(&lock_file);
+			return 1;
 		}
 	}
 
@@ -1166,6 +1099,9 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1203,10 +1139,31 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_base = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret && opts->merge) {
+			create_autostash_ref_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH");
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_base);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
 			return ret;
 		}
 	}
@@ -1216,8 +1173,29 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
+				       new_branch_info->name, "local",
+				       stash_label_base);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index 913be115f2..72967886d7 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4766,15 +4766,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..8f02a664f4 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,201 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git stash list >stash-before &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git stash list >stash-before &&
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v9 4/4] checkout: -m (--merge) uses autostash when switching branches

[Jeff King]

On Fri, Apr 10, 2026 at 09:01:13PM +0000, Harald Nordgren via GitGitGadget wrote:

>  	if (do_merge) {
>  		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> +		if (ret && opts->merge) {
> +			create_autostash_ref_silent(the_repository,
> +						   "CHECKOUT_AUTOSTASH");

This tries to create a root-level ref called CHECKOUT_AUTOSTASH, which
violates the syntax rules given in gitglossary's "ref" entry:

  Ref names must either start with refs/ or be located in the root of
  the hierarchy. For the latter, their name must follow these rules:

    •   The name consists of only upper-case characters or underscores.

    •   The name ends with "_HEAD" or is equal to "HEAD".

Our enforcement of these rules has some holes, but I have a local series
to fix that (which is how I noticed the problem). The entry continues to
list some exceptions:

  There are some irregular refs in the root of the hierarchy that do not
  match these rules. The following list is exhaustive and shall not be
  extended in the future:

    •   AUTO_MERGE

    •   BISECT_EXPECTED_REV

    •   NOTES_MERGE_PARTIAL

    •   NOTES_MERGE_REF

    •   MERGE_AUTOSTASH

We can add CHECKOUT_AUTOSTASH to the list of exceptions, but I wonder if
there is another name we could use that would conform to the usual
rules.

-Peff

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> This tries to create a root-level ref called CHECKOUT_AUTOSTASH, which
> violates the syntax rules given in gitglossary's "ref" entry:
> 
>   Ref names must either start with refs/ or be located in the root of
>   the hierarchy. For the latter, their name must follow these rules:
> 
>     •   The name consists of only upper-case characters or underscores.
> 
>     •   The name ends with "_HEAD" or is equal to "HEAD".


So maybe easiest is just to rename it to CHECKOUT_AUTOSTASH_HEAD?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Jeff King]

On Sat, Apr 11, 2026 at 08:51:09PM +0200, Harald Nordgren wrote:

> > This tries to create a root-level ref called CHECKOUT_AUTOSTASH, which
> > violates the syntax rules given in gitglossary's "ref" entry:
> > 
> >   Ref names must either start with refs/ or be located in the root of
> >   the hierarchy. For the latter, their name must follow these rules:
> > 
> >     •   The name consists of only upper-case characters or underscores.
> > 
> >     •   The name ends with "_HEAD" or is equal to "HEAD".
> 
> 
> So maybe easiest is just to rename it to CHECKOUT_AUTOSTASH_HEAD?

Yeah, that is syntactically valid, if a mouthful. I can't offhand think
of a shorter variant.

-Peff

Re: [PATCH v9 4/4] checkout: -m (--merge) uses autostash when switching branches

[Jeff King]

On Sat, Apr 11, 2026 at 02:38:23PM -0400, Jeff King wrote:

> Our enforcement of these rules has some holes, but I have a local series
> to fix that (which is how I noticed the problem). The entry continues to
> list some exceptions:
> 
>   There are some irregular refs in the root of the hierarchy that do not
>   match these rules. The following list is exhaustive and shall not be
>   extended in the future:
> 
>     •   AUTO_MERGE
> 
>     •   BISECT_EXPECTED_REV
> 
>     •   NOTES_MERGE_PARTIAL
> 
>     •   NOTES_MERGE_REF
> 
>     •   MERGE_AUTOSTASH
> 
> We can add CHECKOUT_AUTOSTASH to the list of exceptions, but I wonder if
> there is another name we could use that would conform to the usual
> rules.

Actually, I misread the documentation I quoted as "list is not
exhaustive". ;) So we would be violating its promise to add
CHECKOUT_AUTOSTASH to the list.

-Peff

Re: [PATCH v9 0/4] checkout: 'autostash' for branch switching

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

>      -    stash: add --ours-label, --theirs-label, --base-label for apply
>      +    stash: add --label-ours, --label-theirs, --label-base for apply
> ...
>      -+`--ours-label=<label>`::
>      -+`--theirs-label=<label>`::
>      -+`--base-label=<label>`::
>      ++`--label-ours=<label>`::
>      ++`--label-theirs=<label>`::
>      ++`--label-base=<label>`::

I guess it is a good change that makes things align better .  One
potential downside is that "--labels-o<TAB>" is slightly longer than
"--ours-l<TAB>", but I do not mind too much either way.

>      @@ sequencer.c: static void create_autostash_internal(struct repository *r,
>        
>       -		printf(_("Created autostash: %s\n"), buf.buf);
>       +		if (!silent)
>      -+			fprintf(stderr, _("Created autostash: %s\n"), buf.buf);
>      ++			printf(_("Created autostash: %s\n"), buf.buf);

Keeping the behaviour of shared code path unchanged would be a safer
move, I guess.  Sending progress-like messages that are meant for
human consumption to the standard error stream may be a good change
but should not be part of this topic, I think.

[PATCH v10 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Harald Nordgren (4):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  33 +++---
 builtin/checkout.c              | 138 ++++++++++------------
 builtin/stash.c                 |  32 ++++--
 sequencer.c                     |  67 ++++++++---
 sequencer.h                     |   4 +
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  29 +++++
 t/t7201-co.sh                   | 195 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 14 files changed, 455 insertions(+), 157 deletions(-)


base-commit: 8c9303b1ffae5b745d1b0a1f98330cf7944d8db0
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v10
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v10
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v9:

 1:  5d5dc1f60e = 1:  aa519c50be stash: add --label-ours, --label-theirs, --label-base for apply
 2:  a1fa04a965 = 2:  8173a4eb72 sequencer: allow create_autostash to run silently
 3:  87216a633b = 3:  f36fedd8c2 sequencer: teach autostash apply to take optional conflict marker labels
 4:  00e0b3196c ! 4:  b6e5546d74 checkout: -m (--merge) uses autostash when switching branches
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		if (ret && opts->merge) {
      +			create_autostash_ref_silent(the_repository,
     -+						   "CHECKOUT_AUTOSTASH");
     ++						   "CHECKOUT_AUTOSTASH_HEAD");
      +			created_autostash = 1;
      +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		}
       		if (ret) {
      +			apply_autostash_ref_with_labels(the_repository,
     -+						       "CHECKOUT_AUTOSTASH",
     ++						       "CHECKOUT_AUTOSTASH_HEAD",
      +						       new_branch_info->name,
      +						       "local",
      +						       stash_label_base);
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +		git_config_push_parameter(cfg.buf);
      +		strbuf_release(&cfg);
      +	}
     -+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH",
     ++	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
      +				       new_branch_info->name, "local",
      +				       stash_label_base);
      +

-- 
gitgitgadget

[PATCH v10 1/4] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 32 +++++++++++++++++++++++++-------
 t/t3903-stash.sh             | 29 +++++++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 67 insertions(+), 11 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..00314e2b13 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label_ours, const char *label_theirs,
+				      const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..00bcb1f802 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,35 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+		test_grep "^<<<<<<< UP" file &&
+		test_grep "^||||||| Stash base" file &&
+		test_grep "^>>>>>>> STASH" file
+	)
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git init empty_labels &&
+	(
+		cd empty_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git stash apply --label-ours= --label-theirs= &&
+		test_grep "^<<<<<<<$" file &&
+		test_grep "^>>>>>>>$" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

[PATCH v10 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 15 +++++++++++----
 sequencer.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..1197d7d8a0 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4702,7 +4703,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4716,17 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, false);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, false);
+}
+
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, true);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..570f804457 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -230,6 +230,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v10 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, and label_base parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --label-ours/--label-theirs/--label-base".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 34 +++++++++++++++++++++++++++-------
 sequencer.h |  3 +++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 1197d7d8a0..913be115f2 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4729,7 +4729,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, true);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4740,6 +4742,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4784,7 +4792,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4803,11 +4812,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4823,7 +4834,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4833,12 +4845,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 570f804457..2c4ff17c4e 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -236,6 +236,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v10 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 +++++-----
 Documentation/git-switch.adoc   |  33 +++---
 builtin/checkout.c              | 138 ++++++++++------------
 sequencer.c                     |  18 ++-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 195 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 9 files changed, 346 insertions(+), 135 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..47391d453f 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
+			rollback_lock_file(&lock_file);
+			return 1;
 		}
 	}
 
@@ -1166,6 +1099,9 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1203,10 +1139,31 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_base = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret && opts->merge) {
+			create_autostash_ref_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH_HEAD");
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH_HEAD",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_base);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
 			return ret;
 		}
 	}
@@ -1216,8 +1173,29 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
+				       new_branch_info->name, "local",
+				       stash_label_base);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index 913be115f2..72967886d7 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4766,15 +4766,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..8f02a664f4 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,201 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git stash list >stash-before &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git stash list >stash-before &&
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v10 0/4] checkout: 'autostash' for branch switching

[Jeff King]

On Sun, Apr 12, 2026 at 11:51:41AM +0000, Harald Nordgren via GitGitGadget wrote:

>  4:  00e0b3196c ! 4:  b6e5546d74 checkout: -m (--merge) uses autostash when switching branches
>      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>        		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>       +		if (ret && opts->merge) {
>       +			create_autostash_ref_silent(the_repository,
>      -+						   "CHECKOUT_AUTOSTASH");
>      ++						   "CHECKOUT_AUTOSTASH_HEAD");
> [...]

Thanks, I can confirm that this version is fine with the stricter
ref-syntax checks.

-Peff

Re: [PATCH v10 0/4] checkout: 'autostash' for branch switching

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> Harald Nordgren (4):
>   stash: add --label-ours, --label-theirs, --label-base for apply
>   sequencer: allow create_autostash to run silently
>   sequencer: teach autostash apply to take optional conflict marker
>     labels
>   checkout: -m (--merge) uses autostash when switching branches

I have been trying this in my real workflow and noticed only one
minor annoyance, which is that the stash entry only says
"autostash", which is not very illuminating.

Because I almost always have either 'master' or 'next' checked out,
when I start outlining a "how about this" kind of change, they are
made on top of these branches, but when I say "checkout -m topic"
after that, I _know_ that the rough draft change that becomes a
stash entry is meant to be part of the "topic", either to extend it
or refine it.  Because the code that creates the stash entry knows
that we were in the process of moving to 'topic', it would be nice
to see the name of the branch we are moving to (i.e., 'topic') on
the title, e.g., "autostash while switching to 'topic'".

Other than that, it is a very pleasant usability enhancement.

Thanks.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Because I almost always have either 'master' or 'next' checked out,
> when I start outlining a "how about this" kind of change, they are
> made on top of these branches, but when I say "checkout -m topic"
> after that, I _know_ that the rough draft change that becomes a
> stash entry is meant to be part of the "topic", either to extend it
> or refine it.  Because the code that creates the stash entry knows
> that we were in the process of moving to 'topic', it would be nice
> to see the name of the branch we are moving to (i.e., 'topic') on
> the title, e.g., "autostash while switching to 'topic'".

Sounds reasonable, but wouldn't it make more sense to call it "autostash
from master". We should still be able to abort the merge and merge it to
some other branch. I feel like the source is more relevant than the
destination, no?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Harald Nordgren <haraldnordgren@gmail.com> writes:

> Sounds reasonable, but wouldn't it make more sense to call it "autostash
> from master". We should still be able to abort the merge and merge it to
> some other branch. I feel like the source is more relevant than the
> destination, no?

The new comment is for reminder, so "I made this while switching
from 'master' to this new 'topic'" theoretically has more reminding
value than "I made this while switching to this new 'topic'".  As I
outlined my workflow, I usually am on 'master' or 'next' when I end
up needing "co -m" option, so "I was on 'master' when I stashed
this" has a much weaker reminding value.  Just like a series of
"autostash" without any context comment irritated me, I'll see many
"autostash on master" that I cannot quite distinguish.

But that may be just me.

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Harald Nordgren <haraldnordgren@gmail.com> writes:
>
>> Sounds reasonable, but wouldn't it make more sense to call it "autostash
>> from master". We should still be able to abort the merge and merge it to
>> some other branch. I feel like the source is more relevant than the
>> destination, no?
>
> The new comment is for reminder, so "I made this while switching
> from 'master' to this new 'topic'" theoretically has more reminding
> value than "I made this while switching to this new 'topic'".  As I
> outlined my workflow, I usually am on 'master' or 'next' when I end
> up needing "co -m" option, so "I was on 'master' when I stashed
> this" has a much weaker reminding value.  Just like a series of
> "autostash" without any context comment irritated me, I'll see many
> "autostash on master" that I cannot quite distinguish.
>
> But that may be just me.

In any case, the topic is already in 'next' and this kind of minor
tweaks are best done as a separate topic once the basic framework
that works reasonably well is established on top.  We may end up
wanting some mechanism to customize the message in the end but that
is something we will find out and become able to decide on the best
design only after we let users use it for a while.

Thanks.

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Harald Nordgren <haraldnordgren@gmail.com> writes:
>
>> Sounds reasonable, but wouldn't it make more sense to call it "autostash
>> from master". We should still be able to abort the merge and merge it to
>> some other branch. I feel like the source is more relevant than the
>> destination, no?
>
> The new comment is for reminder, so "I made this while switching
> from 'master' to this new 'topic'" theoretically has more reminding
> value than "I made this while switching to this new 'topic'".  As I
> outlined my workflow, I usually am on 'master' or 'next' when I end
> up needing "co -m" option, so "I was on 'master' when I stashed
> this" has a much weaker reminding value.  Just like a series of
> "autostash" without any context comment irritated me, I'll see many
> "autostash on master" that I cannot quite distinguish.
>
> But that may be just me.

Thinking about it a bit more, I doubt it would be just me.

The whole point of "git checkout -m other-branch" is "oops, I
started working on this thing while I am on <this> branch, but all
of this changes are irrelevant in the context of this branch and I
realize that they are better done in the context of that other
branch".  So as a name that reminds readers of "git stash list" what
this particular stash entry is about, the name of that other branch
you were switching to is much more relevant than the branch you were
on when you started working on.

[PATCH v11 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Harald Nordgren (4):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 147 ++++++++++------------
 builtin/stash.c                 |  32 +++--
 sequencer.c                     |  87 ++++++++++---
 sequencer.h                     |   8 ++
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  29 +++++
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 14 files changed, 499 insertions(+), 159 deletions(-)


base-commit: 9e8f4e9c04e3efa494e78b710e0c5f6cc77a0a5e
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v11
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v11
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v10:

 1:  aa519c50be = 1:  9ab5431b47 stash: add --label-ours, --label-theirs, --label-base for apply
 2:  8173a4eb72 = 2:  e7f8328e3c sequencer: allow create_autostash to run silently
 3:  f36fedd8c2 = 3:  3242fd3261 sequencer: teach autostash apply to take optional conflict marker labels
 4:  b6e5546d74 ! 4:  97a5d87c81 checkout: -m (--merge) uses autostash when switching branches
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	int do_merge = 1;
      +	int created_autostash = 0;
      +	struct strbuf old_commit_shortname = STRBUF_INIT;
     ++	struct strbuf autostash_msg = STRBUF_INIT;
      +	const char *stash_label_base = NULL;
       
       	trace2_cmd_mode("branch");
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	if (do_merge) {
       		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		if (ret && opts->merge) {
     -+			create_autostash_ref_silent(the_repository,
     -+						   "CHECKOUT_AUTOSTASH_HEAD");
     ++			strbuf_addf(&autostash_msg,
     ++				    "autostash while switching to '%s'",
     ++				    new_branch_info->name);
     ++			create_autostash_ref_silent_with_msg(the_repository,
     ++							    "CHECKOUT_AUTOSTASH_HEAD",
     ++							    autostash_msg.buf);
      +			created_autostash = 1;
      +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		}
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +						       "CHECKOUT_AUTOSTASH_HEAD",
      +						       new_branch_info->name,
      +						       "local",
     -+						       stash_label_base);
     ++						       stash_label_base,
     ++						       autostash_msg.len ? autostash_msg.buf : NULL);
       			branch_info_release(&old_branch_info);
      +			strbuf_release(&old_commit_shortname);
     ++			strbuf_release(&autostash_msg);
       			return ret;
       		}
       	}
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +	}
      +	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
      +				       new_branch_info->name, "local",
     -+				       stash_label_base);
     ++				       stash_label_base,
     ++				       autostash_msg.len ? autostash_msg.buf : NULL);
      +
      +	discard_index(the_repository->index);
      +	if (repo_read_index(the_repository) < 0)
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
       	branch_info_release(&old_branch_info);
      +	strbuf_release(&old_commit_shortname);
     ++	strbuf_release(&autostash_msg);
       
       	return ret || writeout_error;
       }
      
       ## sequencer.c ##
     +@@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list, int offset)
     + static void create_autostash_internal(struct repository *r,
     + 				      const char *path,
     + 				      const char *refname,
     ++				      const char *message,
     + 				      bool silent)
     + {
     + 	struct strbuf buf = STRBUF_INIT;
     +@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     + 		struct object_id oid;
     + 
     + 		strvec_pushl(&stash.args,
     +-			     "stash", "create", "autostash", NULL);
     ++			     "stash", "create",
     ++			     message ? message : "autostash", NULL);
     + 		stash.git_cmd = 1;
     + 		stash.no_stdin = 1;
     + 		strbuf_reset(&buf);
     +@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     + 
     + void create_autostash(struct repository *r, const char *path)
     + {
     +-	create_autostash_internal(r, path, NULL, false);
     ++	create_autostash_internal(r, path, NULL, NULL, false);
     + }
     + 
     + void create_autostash_ref(struct repository *r, const char *refname)
     + {
     +-	create_autostash_internal(r, NULL, refname, false);
     ++	create_autostash_internal(r, NULL, refname, NULL, false);
     + }
     + 
     + void create_autostash_ref_silent(struct repository *r, const char *refname)
     + {
     +-	create_autostash_internal(r, NULL, refname, true);
     ++	create_autostash_internal(r, NULL, refname, NULL, true);
     ++}
     ++
     ++void create_autostash_ref_silent_with_msg(struct repository *r,
     ++					  const char *refname,
     ++					  const char *message)
     ++{
     ++	create_autostash_internal(r, NULL, refname, message, true);
     + }
     + 
     + static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
     + 				    const char *label_ours, const char *label_theirs,
     +-				    const char *label_base)
     ++				    const char *label_base,
     ++				    const char *stash_msg)
     + {
     + 	struct child_process child = CHILD_PROCESS_INIT;
     + 	int ret = 0;
      @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
     + 		strvec_push(&store.args, "stash");
     + 		strvec_push(&store.args, "store");
     + 		strvec_push(&store.args, "-m");
     +-		strvec_push(&store.args, "autostash");
     ++		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
     + 		strvec_push(&store.args, "-q");
       		strvec_push(&store.args, stash_oid);
       		if (run_command(&store))
       			ret = error(_("cannot store %s"), stash_oid);
     @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
       	}
       
       	return ret;
     +@@ sequencer.c: static int apply_save_autostash(const char *path, int attempt_apply)
     + 	strbuf_trim(&stash_oid);
     + 
     + 	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
     +-				      NULL, NULL, NULL);
     ++				      NULL, NULL, NULL, NULL);
     + 
     + 	unlink(path);
     + 	strbuf_release(&stash_oid);
     +@@ sequencer.c: int apply_autostash(const char *path)
     + 
     + int apply_autostash_oid(const char *stash_oid)
     + {
     +-	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
     ++	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
     + }
     + 
     + static int apply_save_autostash_ref(struct repository *r, const char *refname,
     + 				    int attempt_apply,
     + 				    const char *label_ours, const char *label_theirs,
     +-				    const char *label_base)
     ++				    const char *label_base,
     ++				    const char *stash_msg)
     + {
     + 	struct object_id stash_oid;
     + 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
     +@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     + 
     + 	oid_to_hex_r(stash_oid_hex, &stash_oid);
     + 	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
     +-				       label_ours, label_theirs, label_base);
     ++				       label_ours, label_theirs, label_base,
     ++				       stash_msg);
     + 
     + 	refs_delete_ref(get_main_ref_store(r), "", refname,
     + 			&stash_oid, REF_NO_DEREF);
     +@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     + 
     + int save_autostash_ref(struct repository *r, const char *refname)
     + {
     +-	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
     ++	return apply_save_autostash_ref(r, refname, 0,
     ++					NULL, NULL, NULL, NULL);
     + }
     + 
     + int apply_autostash_ref(struct repository *r, const char *refname)
     + {
     +-	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
     ++	return apply_save_autostash_ref(r, refname, 1,
     ++					NULL, NULL, NULL, NULL);
     + }
     + 
     + int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     + 				    const char *label_ours, const char *label_theirs,
     +-				    const char *label_base)
     ++				    const char *label_base,
     ++				    const char *stash_msg)
     + {
     + 	return apply_save_autostash_ref(r, refname, 1,
     +-					label_ours, label_theirs, label_base);
     ++					label_ours, label_theirs, label_base,
     ++					stash_msg);
     + }
     + 
     + static int checkout_onto(struct repository *r, struct replay_opts *opts,
     +
     + ## sequencer.h ##
     +@@ sequencer.h: void commit_post_rewrite(struct repository *r,
     + void create_autostash(struct repository *r, const char *path);
     + void create_autostash_ref(struct repository *r, const char *refname);
     + void create_autostash_ref_silent(struct repository *r, const char *refname);
     ++void create_autostash_ref_silent_with_msg(struct repository *r,
     ++					  const char *refname,
     ++					  const char *message);
     + int save_autostash(const char *path);
     + int save_autostash_ref(struct repository *r, const char *refname);
     + int apply_autostash(const char *path);
     +@@ sequencer.h: int apply_autostash_oid(const char *stash_oid);
     + int apply_autostash_ref(struct repository *r, const char *refname);
     + int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     + 				    const char *label_ours, const char *label_theirs,
     +-				    const char *label_base);
     ++				    const char *label_base,
     ++				    const char *stash_msg);
     + 
     + #define SUMMARY_INITIAL_COMMIT   (1 << 0)
     + #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
      
       ## t/t3420-rebase-autostash.sh ##
      @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	test_cmp expect one
      +'
      +
     ++test_expect_success 'checkout -m autostash message includes target branch' '
     ++	git checkout -f main &&
     ++	git clean -f &&
     ++
     ++	fill 1 2 3 4 5 >one &&
     ++	git checkout -m side >actual 2>&1 &&
     ++	git stash list >stash-list &&
     ++	test_grep "autostash while switching to .side." stash-list &&
     ++	git stash drop &&
     ++	git checkout -f main &&
     ++	git reset --hard
     ++'
     ++
      +test_expect_success 'checkout -m stashes on staged conflicting changes' '
      +	git checkout -f main &&
      +	git clean -f &&

-- 
gitgitgadget

[PATCH v11 1/4] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 32 +++++++++++++++++++++++++-------
 t/t3903-stash.sh             | 29 +++++++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 67 insertions(+), 11 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..00314e2b13 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label_ours, const char *label_theirs,
+				      const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..00bcb1f802 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,35 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+		test_grep "^<<<<<<< UP" file &&
+		test_grep "^||||||| Stash base" file &&
+		test_grep "^>>>>>>> STASH" file
+	)
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git init empty_labels &&
+	(
+		cd empty_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git stash apply --label-ours= --label-theirs= &&
+		test_grep "^<<<<<<<$" file &&
+		test_grep "^>>>>>>>$" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

[PATCH v11 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 15 +++++++++++----
 sequencer.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..1197d7d8a0 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,8 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4702,7 +4703,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4716,17 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, false);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, false);
+}
+
+void create_autostash_ref_silent(struct repository *r, const char *refname)
+{
+	create_autostash_internal(r, NULL, refname, true);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..570f804457 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -230,6 +230,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_silent(struct repository *r, const char *refname);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v11 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, and label_base parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --label-ours/--label-theirs/--label-base".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 34 +++++++++++++++++++++++++++-------
 sequencer.h |  3 +++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 1197d7d8a0..913be115f2 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4729,7 +4729,9 @@ void create_autostash_ref_silent(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, true);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4740,6 +4742,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4784,7 +4792,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4803,11 +4812,13 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4823,7 +4834,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4833,12 +4845,20 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 570f804457..2c4ff17c4e 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -236,6 +236,9 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v11 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 147 ++++++++++------------
 sequencer.c                     |  62 +++++++---
 sequencer.h                     |   6 +-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 10 files changed, 403 insertions(+), 150 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..2adfefa085 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
+			rollback_lock_file(&lock_file);
+			return 1;
 		}
 	}
 
@@ -1166,6 +1099,10 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	struct strbuf autostash_msg = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1203,10 +1140,37 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_base = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret && opts->merge) {
+			strbuf_addf(&autostash_msg,
+				    "autostash while switching to '%s'",
+				    new_branch_info->name);
+			create_autostash_ref_silent_with_msg(the_repository,
+							    "CHECKOUT_AUTOSTASH_HEAD",
+							    autostash_msg.buf);
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH_HEAD",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_base,
+						       autostash_msg.len ? autostash_msg.buf : NULL);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
+			strbuf_release(&autostash_msg);
 			return ret;
 		}
 	}
@@ -1216,8 +1180,31 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
+				       new_branch_info->name, "local",
+				       stash_label_base,
+				       autostash_msg.len ? autostash_msg.buf : NULL);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
+	strbuf_release(&autostash_msg);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index 913be115f2..febdb5b20a 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4658,6 +4658,7 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
 				      const char *refname,
+				      const char *message,
 				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
@@ -4680,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
 		struct object_id oid;
 
 		strvec_pushl(&stash.args,
-			     "stash", "create", "autostash", NULL);
+			     "stash", "create",
+			     message ? message : "autostash", NULL);
 		stash.git_cmd = 1;
 		stash.no_stdin = 1;
 		strbuf_reset(&buf);
@@ -4716,22 +4718,30 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL, false);
+	create_autostash_internal(r, path, NULL, NULL, false);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname, false);
+	create_autostash_internal(r, NULL, refname, NULL, false);
 }
 
 void create_autostash_ref_silent(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname, true);
+	create_autostash_internal(r, NULL, refname, NULL, true);
+}
+
+void create_autostash_ref_silent_with_msg(struct repository *r,
+					  const char *refname,
+					  const char *message)
+{
+	create_autostash_internal(r, NULL, refname, message, true);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 				    const char *label_ours, const char *label_theirs,
-				    const char *label_base)
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4761,20 +4771,28 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, "stash");
 		strvec_push(&store.args, "store");
 		strvec_push(&store.args, "-m");
-		strvec_push(&store.args, "autostash");
+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
 		strvec_push(&store.args, "-q");
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
@@ -4793,7 +4811,7 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	strbuf_trim(&stash_oid);
 
 	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
-				      NULL, NULL, NULL);
+				      NULL, NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4812,13 +4830,14 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
 				    int attempt_apply,
 				    const char *label_ours, const char *label_theirs,
-				    const char *label_base)
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4835,7 +4854,8 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
 	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
-				       label_ours, label_theirs, label_base);
+				       label_ours, label_theirs, label_base,
+				       stash_msg);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4845,20 +4865,24 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
+	return apply_save_autostash_ref(r, refname, 0,
+					NULL, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
+	return apply_save_autostash_ref(r, refname, 1,
+					NULL, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
 				    const char *label_ours, const char *label_theirs,
-				    const char *label_base)
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	return apply_save_autostash_ref(r, refname, 1,
-					label_ours, label_theirs, label_base);
+					label_ours, label_theirs, label_base,
+					stash_msg);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 2c4ff17c4e..67de755053 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -231,6 +231,9 @@ void commit_post_rewrite(struct repository *r,
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
 void create_autostash_ref_silent(struct repository *r, const char *refname);
+void create_autostash_ref_silent_with_msg(struct repository *r,
+					  const char *refname,
+					  const char *message);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
@@ -238,7 +241,8 @@ int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
 				    const char *label_ours, const char *label_theirs,
-				    const char *label_base);
+				    const char *label_base,
+				    const char *stash_msg);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..c474c6759f 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,214 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git stash list >stash-before &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m autostash message includes target branch' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	git stash list >stash-list &&
+	test_grep "autostash while switching to .side." stash-list &&
+	git stash drop &&
+	git checkout -f main &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git stash list >stash-before &&
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

[PATCH v12 0/4] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Harald Nordgren (4):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: -m (--merge) uses autostash when switching branches

 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 147 ++++++++++------------
 builtin/stash.c                 |  32 +++--
 sequencer.c                     |  81 ++++++++++---
 sequencer.h                     |   6 +
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  29 +++++
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 14 files changed, 491 insertions(+), 159 deletions(-)


base-commit: 9e8f4e9c04e3efa494e78b710e0c5f6cc77a0a5e
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v12
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v12
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v11:

 1:  9ab5431b47 = 1:  9ab5431b47 stash: add --label-ours, --label-theirs, --label-base for apply
 2:  e7f8328e3c ! 2:  e11a622bdf sequencer: allow create_autostash to run silently
     @@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list,
       				      const char *path,
      -				      const char *refname)
      +				      const char *refname,
     ++				      const char *message,
      +				      bool silent)
       {
       	struct strbuf buf = STRBUF_INIT;
       	struct lock_file lock_file = LOCK_INIT;
     +@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     + 		struct object_id oid;
     + 
     + 		strvec_pushl(&stash.args,
     +-			     "stash", "create", "autostash", NULL);
     ++			     "stash", "create",
     ++			     message ? message : "autostash", NULL);
     + 		stash.git_cmd = 1;
     + 		stash.no_stdin = 1;
     + 		strbuf_reset(&buf);
      @@ sequencer.c: static void create_autostash_internal(struct repository *r,
       					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
       		}
     @@ sequencer.c: static void create_autostash_internal(struct repository *r,
       void create_autostash(struct repository *r, const char *path)
       {
      -	create_autostash_internal(r, path, NULL);
     -+	create_autostash_internal(r, path, NULL, false);
     ++	create_autostash_internal(r, path, NULL, NULL, false);
       }
       
       void create_autostash_ref(struct repository *r, const char *refname)
       {
      -	create_autostash_internal(r, NULL, refname);
     -+	create_autostash_internal(r, NULL, refname, false);
     ++	create_autostash_internal(r, NULL, refname, NULL, false);
      +}
      +
     -+void create_autostash_ref_silent(struct repository *r, const char *refname)
     ++void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
     ++				 const char *message)
      +{
     -+	create_autostash_internal(r, NULL, refname, true);
     ++	create_autostash_internal(r, NULL, refname, message, true);
       }
       
       static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     @@ sequencer.h: void commit_post_rewrite(struct repository *r,
       
       void create_autostash(struct repository *r, const char *path);
       void create_autostash_ref(struct repository *r, const char *refname);
     -+void create_autostash_ref_silent(struct repository *r, const char *refname);
     ++void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
     ++				 const char *message);
       int save_autostash(const char *path);
       int save_autostash_ref(struct repository *r, const char *refname);
       int apply_autostash(const char *path);
 3:  3242fd3261 ! 3:  4593745e90 sequencer: teach autostash apply to take optional conflict marker labels
     @@ Commit message
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
       ## sequencer.c ##
     -@@ sequencer.c: void create_autostash_ref_silent(struct repository *r, const char *refname)
     - 	create_autostash_internal(r, NULL, refname, true);
     +@@ sequencer.c: void create_autostash_ref_with_msg_silent(struct repository *r, const char *refn
     + 	create_autostash_internal(r, NULL, refname, message, true);
       }
       
      -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
      +static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
      +				    const char *label_ours, const char *label_theirs,
     -+				    const char *label_base)
     ++				    const char *label_base,
     ++				    const char *stash_msg)
       {
       	struct child_process child = CHILD_PROCESS_INIT;
       	int ret = 0;
     @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
       		strvec_push(&child.args, stash_oid);
       		ret = run_command(&child);
       	}
     +@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     + 		strvec_push(&store.args, "stash");
     + 		strvec_push(&store.args, "store");
     + 		strvec_push(&store.args, "-m");
     +-		strvec_push(&store.args, "autostash");
     ++		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
     + 		strvec_push(&store.args, "-q");
     + 		strvec_push(&store.args, stash_oid);
     + 		if (run_command(&store))
      @@ sequencer.c: static int apply_save_autostash(const char *path, int attempt_apply)
       	}
       	strbuf_trim(&stash_oid);
       
      -	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
      +	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
     -+				      NULL, NULL, NULL);
     ++				      NULL, NULL, NULL, NULL);
       
       	unlink(path);
       	strbuf_release(&stash_oid);
     @@ sequencer.c: int apply_autostash(const char *path)
       int apply_autostash_oid(const char *stash_oid)
       {
      -	return apply_save_autostash_oid(stash_oid, 1);
     -+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
     ++	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
       }
       
       static int apply_save_autostash_ref(struct repository *r, const char *refname,
      -				    int attempt_apply)
      +				    int attempt_apply,
      +				    const char *label_ours, const char *label_theirs,
     -+				    const char *label_base)
     ++				    const char *label_base,
     ++				    const char *stash_msg)
       {
       	struct object_id stash_oid;
       	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
     @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
       	oid_to_hex_r(stash_oid_hex, &stash_oid);
      -	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
      +	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
     -+				       label_ours, label_theirs, label_base);
     ++				       label_ours, label_theirs, label_base,
     ++				       stash_msg);
       
       	refs_delete_ref(get_main_ref_store(r), "", refname,
       			&stash_oid, REF_NO_DEREF);
     @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
       int save_autostash_ref(struct repository *r, const char *refname)
       {
      -	return apply_save_autostash_ref(r, refname, 0);
     -+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
     ++	return apply_save_autostash_ref(r, refname, 0,
     ++					NULL, NULL, NULL, NULL);
       }
       
       int apply_autostash_ref(struct repository *r, const char *refname)
       {
      -	return apply_save_autostash_ref(r, refname, 1);
     -+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
     ++	return apply_save_autostash_ref(r, refname, 1,
     ++					NULL, NULL, NULL, NULL);
      +}
      +
      +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
      +				    const char *label_ours, const char *label_theirs,
     -+				    const char *label_base)
     ++				    const char *label_base,
     ++				    const char *stash_msg)
      +{
      +	return apply_save_autostash_ref(r, refname, 1,
     -+					label_ours, label_theirs, label_base);
     ++					label_ours, label_theirs, label_base,
     ++					stash_msg);
       }
       
       static int checkout_onto(struct repository *r, struct replay_opts *opts,
     @@ sequencer.h: int save_autostash_ref(struct repository *r, const char *refname);
       int apply_autostash_ref(struct repository *r, const char *refname);
      +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
      +				    const char *label_ours, const char *label_theirs,
     -+				    const char *label_base);
     ++				    const char *label_base,
     ++				    const char *stash_msg);
       
       #define SUMMARY_INITIAL_COMMIT   (1 << 0)
       #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
 4:  97a5d87c81 ! 4:  911e520431 checkout: -m (--merge) uses autostash when switching branches
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +			strbuf_addf(&autostash_msg,
      +				    "autostash while switching to '%s'",
      +				    new_branch_info->name);
     -+			create_autostash_ref_silent_with_msg(the_repository,
     -+							    "CHECKOUT_AUTOSTASH_HEAD",
     -+							    autostash_msg.buf);
     ++			create_autostash_ref_with_msg_silent(the_repository,
     ++						   "CHECKOUT_AUTOSTASH_HEAD",
     ++						   autostash_msg.buf);
      +			created_autostash = 1;
      +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		}
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       }
      
       ## sequencer.c ##
     -@@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list, int offset)
     - static void create_autostash_internal(struct repository *r,
     - 				      const char *path,
     - 				      const char *refname,
     -+				      const char *message,
     - 				      bool silent)
     - {
     - 	struct strbuf buf = STRBUF_INIT;
     -@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     - 		struct object_id oid;
     - 
     - 		strvec_pushl(&stash.args,
     --			     "stash", "create", "autostash", NULL);
     -+			     "stash", "create",
     -+			     message ? message : "autostash", NULL);
     - 		stash.git_cmd = 1;
     - 		stash.no_stdin = 1;
     - 		strbuf_reset(&buf);
     -@@ sequencer.c: static void create_autostash_internal(struct repository *r,
     - 
     - void create_autostash(struct repository *r, const char *path)
     - {
     --	create_autostash_internal(r, path, NULL, false);
     -+	create_autostash_internal(r, path, NULL, NULL, false);
     - }
     - 
     - void create_autostash_ref(struct repository *r, const char *refname)
     - {
     --	create_autostash_internal(r, NULL, refname, false);
     -+	create_autostash_internal(r, NULL, refname, NULL, false);
     - }
     - 
     - void create_autostash_ref_silent(struct repository *r, const char *refname)
     - {
     --	create_autostash_internal(r, NULL, refname, true);
     -+	create_autostash_internal(r, NULL, refname, NULL, true);
     -+}
     -+
     -+void create_autostash_ref_silent_with_msg(struct repository *r,
     -+					  const char *refname,
     -+					  const char *message)
     -+{
     -+	create_autostash_internal(r, NULL, refname, message, true);
     - }
     - 
     - static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
     - 				    const char *label_ours, const char *label_theirs,
     --				    const char *label_base)
     -+				    const char *label_base,
     -+				    const char *stash_msg)
     - {
     - 	struct child_process child = CHILD_PROCESS_INIT;
     - 	int ret = 0;
      @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
     - 		strvec_push(&store.args, "stash");
     - 		strvec_push(&store.args, "store");
     - 		strvec_push(&store.args, "-m");
     --		strvec_push(&store.args, "autostash");
     -+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
     - 		strvec_push(&store.args, "-q");
       		strvec_push(&store.args, stash_oid);
       		if (run_command(&store))
       			ret = error(_("cannot store %s"), stash_oid);
     @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
       	}
       
       	return ret;
     -@@ sequencer.c: static int apply_save_autostash(const char *path, int attempt_apply)
     - 	strbuf_trim(&stash_oid);
     - 
     - 	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
     --				      NULL, NULL, NULL);
     -+				      NULL, NULL, NULL, NULL);
     - 
     - 	unlink(path);
     - 	strbuf_release(&stash_oid);
     -@@ sequencer.c: int apply_autostash(const char *path)
     - 
     - int apply_autostash_oid(const char *stash_oid)
     - {
     --	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
     -+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
     - }
     - 
     - static int apply_save_autostash_ref(struct repository *r, const char *refname,
     - 				    int attempt_apply,
     - 				    const char *label_ours, const char *label_theirs,
     --				    const char *label_base)
     -+				    const char *label_base,
     -+				    const char *stash_msg)
     - {
     - 	struct object_id stash_oid;
     - 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
     -@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     - 
     - 	oid_to_hex_r(stash_oid_hex, &stash_oid);
     - 	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
     --				       label_ours, label_theirs, label_base);
     -+				       label_ours, label_theirs, label_base,
     -+				       stash_msg);
     - 
     - 	refs_delete_ref(get_main_ref_store(r), "", refname,
     - 			&stash_oid, REF_NO_DEREF);
     -@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
     - 
     - int save_autostash_ref(struct repository *r, const char *refname)
     - {
     --	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
     -+	return apply_save_autostash_ref(r, refname, 0,
     -+					NULL, NULL, NULL, NULL);
     - }
     - 
     - int apply_autostash_ref(struct repository *r, const char *refname)
     - {
     --	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
     -+	return apply_save_autostash_ref(r, refname, 1,
     -+					NULL, NULL, NULL, NULL);
     - }
     - 
     - int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     - 				    const char *label_ours, const char *label_theirs,
     --				    const char *label_base)
     -+				    const char *label_base,
     -+				    const char *stash_msg)
     - {
     - 	return apply_save_autostash_ref(r, refname, 1,
     --					label_ours, label_theirs, label_base);
     -+					label_ours, label_theirs, label_base,
     -+					stash_msg);
     - }
     - 
     - static int checkout_onto(struct repository *r, struct replay_opts *opts,
     -
     - ## sequencer.h ##
     -@@ sequencer.h: void commit_post_rewrite(struct repository *r,
     - void create_autostash(struct repository *r, const char *path);
     - void create_autostash_ref(struct repository *r, const char *refname);
     - void create_autostash_ref_silent(struct repository *r, const char *refname);
     -+void create_autostash_ref_silent_with_msg(struct repository *r,
     -+					  const char *refname,
     -+					  const char *message);
     - int save_autostash(const char *path);
     - int save_autostash_ref(struct repository *r, const char *refname);
     - int apply_autostash(const char *path);
     -@@ sequencer.h: int apply_autostash_oid(const char *stash_oid);
     - int apply_autostash_ref(struct repository *r, const char *refname);
     - int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     - 				    const char *label_ours, const char *label_theirs,
     --				    const char *label_base);
     -+				    const char *label_base,
     -+				    const char *stash_msg);
     - 
     - #define SUMMARY_INITIAL_COMMIT   (1 << 0)
     - #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
      
       ## t/t3420-rebase-autostash.sh ##
      @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {

-- 
gitgitgadget

[PATCH v12 1/4] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 32 +++++++++++++++++++++++++-------
 t/t3903-stash.sh             | 29 +++++++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 67 insertions(+), 11 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..00314e2b13 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -590,8 +590,11 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 		die(_("could not write index"));
 }
 
-static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+static int do_apply_stash_with_labels(const char *prefix,
+				      struct stash_info *info,
+				      int index, int quiet,
+				      const char *label_ours, const char *label_theirs,
+				      const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +646,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -717,17 +720,31 @@ restore_untracked:
 	return ret;
 }
 
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+			  int index, int quiet)
+{
+	return do_apply_stash_with_labels(prefix, info, index, quiet,
+					  NULL, NULL, NULL);
+}
+
 static int apply_stash(int argc, const char **argv, const char *prefix,
 		       struct repository *repo UNUSED)
 {
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +754,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
+					 label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..00bcb1f802 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,35 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git init conflict_labels &&
+	(
+		cd conflict_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+		test_grep "^<<<<<<< UP" file &&
+		test_grep "^||||||| Stash base" file &&
+		test_grep "^>>>>>>> STASH" file
+	)
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git init empty_labels &&
+	(
+		cd empty_labels &&
+		test_commit base file &&
+		echo stashed >file &&
+		git stash push -m "stashed" &&
+		test_commit upstream file &&
+		test_must_fail git stash apply --label-ours= --label-theirs= &&
+		test_grep "^<<<<<<<$" file &&
+		test_grep "^>>>>>>>$" file
+	)
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

Re: [PATCH v12 1/4] stash: add --label-ours, --label-theirs, --label-base for apply

[Phillip Wood]

Hi Harald

On 14/04/2026 13:59, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Allow callers of "git stash apply" to pass custom labels for conflict
> markers instead of the default "Updated upstream" and "Stashed changes".
> Document the new options and add a test.
> 
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> [...]
> diff --git a/builtin/stash.c b/builtin/stash.c
> index 0d27b2fb1f..00314e2b13 100644
> --- a/builtin/stash.c
> +++ b/builtin/stash.c
> @@ -44,7 +44,7 @@
> [...]
> -static int do_apply_stash(const char *prefix, struct stash_info *info,
> -			  int index, int quiet)
> +static int do_apply_stash_with_labels(const char *prefix,
> +				      struct stash_info *info,
> +				      int index, int quiet,
> +				      const char *label_ours, const char *label_theirs,
> +				      const char *label_base)

There are only four callers of do_apply_stash so it might be better just 
to change the function signature and update the existing callers rather 
than adding another function.

> diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
> index 70879941c2..00bcb1f802 100755
> --- a/t/t3903-stash.sh
> +++ b/t/t3903-stash.sh
> @@ -1666,6 +1666,35 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
>   	)
>   '
>   
> +test_expect_success 'apply with custom conflict labels' '
> +	git init conflict_labels &&
> +	(

I'm still unclear why we're creating a new repository here. Our test 
suite is slow enough already without each test spending time creating 
its own repository. There doesn't seem to be anything here that requires 
isolating the test in this way.

Apart from that everything else looks good to me

Thanks

Phillip

> +		cd conflict_labels &&
> +		test_commit base file &&
> +		echo stashed >file &&
> +		git stash push -m "stashed" &&
> +		test_commit upstream file &&
> +		test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
> +		test_grep "^<<<<<<< UP" file &&
> +		test_grep "^||||||| Stash base" file &&
> +		test_grep "^>>>>>>> STASH" file
> +	)
> +'
> +
> +test_expect_success 'apply with empty conflict labels' '
> +	git init empty_labels &&
> +	(
> +		cd empty_labels &&
> +		test_commit base file &&
> +		echo stashed >file &&
> +		git stash push -m "stashed" &&
> +		test_commit upstream file &&
> +		test_must_fail git stash apply --label-ours= --label-theirs= &&
> +		test_grep "^<<<<<<<$" file &&
> +		test_grep "^>>>>>>>$" file
> +	)
> +'
> +
>   test_expect_success 'stash create reports a locked index' '
>   	test_when_finished "rm -rf repo" &&
>   	git init repo &&
> diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
> index 29dad98c49..659ad4ec97 100644
> --- a/xdiff/xmerge.c
> +++ b/xdiff/xmerge.c
> @@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
>   			      int size, int i, int style,
>   			      xdmerge_t *m, char *dest, int marker_size)
>   {
> -	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
> -	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
> -	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
> +	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
> +	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
> +	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
>   	int needs_cr = is_cr_needed(xe1, xe2, m);
>   
>   	if (marker_size <= 0)

Re: [PATCH v12 1/4] stash: add --label-ours, --label-theirs, --label-base for apply

[Junio C Hamano]

Phillip Wood <phillip.wood123@gmail.com> writes:

>> +static int do_apply_stash_with_labels(const char *prefix,
>> +				      struct stash_info *info,
>> +				      int index, int quiet,
>> +				      const char *label_ours, const char *label_theirs,
>> +				      const char *label_base)
>
> There are only four callers of do_apply_stash so it might be better just 
> to change the function signature and update the existing callers rather 
> than adding another function.
>
>> diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
>> index 70879941c2..00bcb1f802 100755
>> --- a/t/t3903-stash.sh
>> +++ b/t/t3903-stash.sh
>> @@ -1666,6 +1666,35 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
>>   	)
>>   '
>>   
>> +test_expect_success 'apply with custom conflict labels' '
>> +	git init conflict_labels &&
>> +	(
>
> I'm still unclear why we're creating a new repository here. Our test 
> suite is slow enough already without each test spending time creating 
> its own repository. There doesn't seem to be anything here that requires 
> isolating the test in this way.

Both are exellent points.  

I also agree with your comments on create_autostash_ref() in [2/4],
extending apply_autostash_ref() with optional three or four extra
parameters and updating existing callers in [3/4].

I have v10 already merged to 'next', but I think it is better to
revert the merge and give these finishing touches, as we are not
in a rush to add more topics to 'next' before 2.54 final anyway.

Thanks.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> There are only four callers of do_apply_stash so it might be better just 
> to change the function signature and update the existing callers rather 
> than adding another function.

Also a good point, and I will update it.

Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> > +test_expect_success 'apply with custom conflict labels' '
> > +	git init conflict_labels &&
> > +	(
> 
> I'm still unclear why we're creating a new repository here. Our test 
> suite is slow enough already without each test spending time creating 
> its own repository. There doesn't seem to be anything here that requires 
> isolating the test in this way.

Yes, I want this too, but I had some problems to get it to work. Found a
way now I think, but the cleanup is not 100% trivial (this is the only
reason to run anything inside a new repo).

Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Phillip Wood]

On 14/04/2026 21:08, Harald Nordgren wrote:
>>> +test_expect_success 'apply with custom conflict labels' '
>>> +	git init conflict_labels &&
>>> +	(
>>
>> I'm still unclear why we're creating a new repository here. Our test
>> suite is slow enough already without each test spending time creating
>> its own repository. There doesn't seem to be anything here that requires
>> isolating the test in this way.
> 
> Yes, I want this too, but I had some problems to get it to work. Found a
> way now I think, but the cleanup is not 100% trivial (this is the only
> reason to run anything inside a new repo).

Normally the first test would setup some commits with test_commit() that 
creates a tag so you can just use "git reset --hard <tag>" to start your 
test from a known state. Unfortunately setup_stash() does not use 
test_commit() so there are no tags. It would be useful to fix that by 
adding a line that creates a tag so that future test authors do not face 
the same problem.

Thanks

Phillip

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> Normally the first test would setup some commits with test_commit() that
> creates a tag so you can just use "git reset --hard <tag>" to start your
> test from a known state. Unfortunately setup_stash() does not use
> test_commit() so there are no tags. It would be useful to fix that by
> adding a line that creates a tag so that future test authors do not face
> the same problem.

Sounds reasonable, but it's surprisingly easy to break the subsequent
tests.

My solution now will be to move these tests to last in the test file.


Harald

[PATCH v12 2/4] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 20 +++++++++++++++-----
 sequencer.h |  2 ++
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..780628aab4 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,9 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      const char *message,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4679,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
 		struct object_id oid;
 
 		strvec_pushl(&stash.args,
-			     "stash", "create", "autostash", NULL);
+			     "stash", "create",
+			     message ? message : "autostash", NULL);
 		stash.git_cmd = 1;
 		stash.no_stdin = 1;
 		strbuf_reset(&buf);
@@ -4702,7 +4705,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4718,18 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, NULL, false);
 }
 
 void create_autostash_ref(struct repository *r, const char *refname)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, NULL, false);
+}
+
+void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
+				 const char *message)
+{
+	create_autostash_internal(r, NULL, refname, message, true);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..5d3bc83314 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -230,6 +230,8 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
+				 const char *message);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

Re: [PATCH v12 2/4] sequencer: allow create_autostash to run silently

[Phillip Wood]

Hi Harald

On 14/04/2026 13:59, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add a silent parameter to create_autostash_internal and introduce
> create_autostash_ref_silent so that callers can create an autostash
> without printing the "Created autostash" message.
> 
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>

I wonder if we should just update the two callers of 
create_autostash_ref() instead of adding a new function but the 
implementation looks sensible

Thanks

Phillip

>   sequencer.c | 20 +++++++++++++++-----
>   sequencer.h |  2 ++
>   2 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/sequencer.c b/sequencer.c
> index b7d8dca47f..780628aab4 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4657,7 +4657,9 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
>   
>   static void create_autostash_internal(struct repository *r,
>   				      const char *path,
> -				      const char *refname)
> +				      const char *refname,
> +				      const char *message,
> +				      bool silent)
>   {
>   	struct strbuf buf = STRBUF_INIT;
>   	struct lock_file lock_file = LOCK_INIT;
> @@ -4679,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
>   		struct object_id oid;
>   
>   		strvec_pushl(&stash.args,
> -			     "stash", "create", "autostash", NULL);
> +			     "stash", "create",
> +			     message ? message : "autostash", NULL);
>   		stash.git_cmd = 1;
>   		stash.no_stdin = 1;
>   		strbuf_reset(&buf);
> @@ -4702,7 +4705,8 @@ static void create_autostash_internal(struct repository *r,
>   					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
>   		}
>   
> -		printf(_("Created autostash: %s\n"), buf.buf);
> +		if (!silent)
> +			printf(_("Created autostash: %s\n"), buf.buf);
>   		if (reset_head(r, &ropts) < 0)
>   			die(_("could not reset --hard"));
>   		discard_index(r->index);
> @@ -4714,12 +4718,18 @@ static void create_autostash_internal(struct repository *r,
>   
>   void create_autostash(struct repository *r, const char *path)
>   {
> -	create_autostash_internal(r, path, NULL);
> +	create_autostash_internal(r, path, NULL, NULL, false);
>   }
>   
>   void create_autostash_ref(struct repository *r, const char *refname)
>   {
> -	create_autostash_internal(r, NULL, refname);
> +	create_autostash_internal(r, NULL, refname, NULL, false);
> +}
> +
> +void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
> +				 const char *message)
> +{
> +	create_autostash_internal(r, NULL, refname, message, true);
>   }
>   
>   static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
> diff --git a/sequencer.h b/sequencer.h
> index a6fa670c7c..5d3bc83314 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -230,6 +230,8 @@ void commit_post_rewrite(struct repository *r,
>   
>   void create_autostash(struct repository *r, const char *path);
>   void create_autostash_ref(struct repository *r, const char *refname);
> +void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
> +				 const char *message);
>   int save_autostash(const char *path);
>   int save_autostash_ref(struct repository *r, const char *refname);
>   int apply_autostash(const char *path);

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> > From: Harald Nordgren <haraldnordgren@gmail.com>
> > 
> > Add a silent parameter to create_autostash_internal and introduce
> > create_autostash_ref_silent so that callers can create an autostash
> > without printing the "Created autostash" message.
> > 
> > Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> 
> I wonder if we should just update the two callers of 
> create_autostash_ref() instead of adding a new function but the 
> implementation looks sensible

Good point, I will update it!


Harald

[PATCH v12 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, and label_base parameters to the autostash
apply machinery so callers can pass custom conflict marker labels
through to "git stash apply --label-ours/--label-theirs/--label-base".
Introduce apply_autostash_ref_with_labels() for callers that want
to pass labels.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 sequencer.c | 43 +++++++++++++++++++++++++++++++++++--------
 sequencer.h |  4 ++++
 2 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 780628aab4..c2516000bd 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4732,7 +4732,10 @@ void create_autostash_ref_with_msg_silent(struct repository *r, const char *refn
 	create_autostash_internal(r, NULL, refname, message, true);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4743,6 +4746,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4756,7 +4765,7 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		strvec_push(&store.args, "stash");
 		strvec_push(&store.args, "store");
 		strvec_push(&store.args, "-m");
-		strvec_push(&store.args, "autostash");
+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
 		strvec_push(&store.args, "-q");
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
@@ -4787,7 +4796,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4806,11 +4816,14 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4826,7 +4839,9 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base,
+				       stash_msg);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4836,12 +4851,24 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0,
+					NULL, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1,
+					NULL, NULL, NULL, NULL);
+}
+
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
+{
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base,
+					stash_msg);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 5d3bc83314..b0c891d3b6 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -237,6 +237,10 @@ int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

Re: [PATCH v12 3/4] sequencer: teach autostash apply to take optional conflict marker labels

[Phillip Wood]

Hi Harald

On 14/04/2026 13:59, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add label_ours, label_theirs, and label_base parameters to the autostash
> apply machinery so callers can pass custom conflict marker labels
> through to "git stash apply --label-ours/--label-theirs/--label-base".
> Introduce apply_autostash_ref_with_labels() for callers that want
> to pass labels.
> 
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> [...]
> diff --git a/sequencer.c b/sequencer.c
> index 780628aab4..c2516000bd 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4732,7 +4732,10 @@ void create_autostash_ref_with_msg_silent(struct repository *r, const char *refn
>   	create_autostash_internal(r, NULL, refname, message, true);
>   }
>   
> -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
> +static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
> +				    const char *label_ours, const char *label_theirs,
> +				    const char *label_base,
> +				    const char *stash_msg)

I'm confused why to need to provide a message when we're storing an 
existing stash that already has the message that we want to use.
> diff --git a/sequencer.h b/sequencer.h
> index 5d3bc83314..b0c891d3b6 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -237,6 +237,10 @@ int save_autostash_ref(struct repository *r, const char *refname);
>   int apply_autostash(const char *path);
>   int apply_autostash_oid(const char *stash_oid);
>   int apply_autostash_ref(struct repository *r, const char *refname);
> +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
> +				    const char *label_ours, const char *label_theirs,
> +				    const char *label_base,
> +				    const char *stash_msg);

Do we need a new function, or can we just update the existing callers to 
pass NULL? In the future I think we'll want to pass better conflict 
labels and updating them now to pass NULL makes that easier.

Thanks

Phillip

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> > diff --git a/sequencer.h b/sequencer.h
> > index 5d3bc83314..b0c891d3b6 100644
> > --- a/sequencer.h
> > +++ b/sequencer.h
> > @@ -237,6 +237,10 @@ int save_autostash_ref(struct repository *r, const char *refname);
> >   int apply_autostash(const char *path);
> >   int apply_autostash_oid(const char *stash_oid);
> >   int apply_autostash_ref(struct repository *r, const char *refname);
> > +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
> > +                                 const char *label_ours, const char *label_theirs,
> > +                                 const char *label_base,
> > +                                 const char *stash_msg);

Fair enough, will update in the next patch!


Harald

[PATCH v12 4/4] checkout: -m (--merge) uses autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", local modifications
can block the switch.  Teach the -m flow to create a temporary stash
before switching and reapply it after.  On success, only "Applied
autostash." is shown.  If reapplying causes conflicts, the stash is
kept and the user is told they can resolve and run "git stash drop",
or run "git reset --hard" and later "git stash pop" to recover their
changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 147 ++++++++++------------
 sequencer.c                     |  18 ++-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 9 files changed, 368 insertions(+), 135 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..a7a93e1c6b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge)
-				return 1;
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit)
-				return 1;
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret)
-				return ret;
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret)
-				return ret;
+			rollback_lock_file(&lock_file);
+			return 1;
 		}
 	}
 
@@ -1166,6 +1099,10 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	struct strbuf autostash_msg = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1203,10 +1140,37 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_base = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret && opts->merge) {
+			strbuf_addf(&autostash_msg,
+				    "autostash while switching to '%s'",
+				    new_branch_info->name);
+			create_autostash_ref_with_msg_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH_HEAD",
+						   autostash_msg.buf);
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			apply_autostash_ref_with_labels(the_repository,
+						       "CHECKOUT_AUTOSTASH_HEAD",
+						       new_branch_info->name,
+						       "local",
+						       stash_label_base,
+						       autostash_msg.len ? autostash_msg.buf : NULL);
 			branch_info_release(&old_branch_info);
+			strbuf_release(&old_commit_shortname);
+			strbuf_release(&autostash_msg);
 			return ret;
 		}
 	}
@@ -1216,8 +1180,31 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
+				       new_branch_info->name, "local",
+				       stash_label_base,
+				       autostash_msg.len ? autostash_msg.buf : NULL);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
+	    new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
+	strbuf_release(&autostash_msg);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index c2516000bd..b78a8ff092 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4770,15 +4770,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..c474c6759f 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,214 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git stash list >stash-before &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m autostash message includes target branch' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	git stash list >stash-list &&
+	test_grep "autostash while switching to .side." stash-list &&
+	git stash drop &&
+	git checkout -f main &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git stash list >stash-before &&
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v12 4/4] checkout: -m (--merge) uses autostash when switching branches

[Phillip Wood]

Hi Harald

For the subject line I think

     checkout -m: autostash when switching branches

would be more in keeping with our usual style.

On 14/04/2026 13:59, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> When switching branches with "git checkout -m", local modifications
> can block the switch. 

Really? Isn't the point of "checkout -m" to merge the local 
modifications into the branch that's being checked out?

> Teach the -m flow to create a temporary stash
> before switching and reapply it after.  On success, only "Applied
> autostash." is shown. 

and a diff of the local changes?

> If reapplying causes conflicts, the stash is
> kept and the user is told they can resolve and run "git stash drop",
> or run "git reset --hard" and later "git stash pop" to recover their
> changes.
> 
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>

I've skipped the docs as I'm short on time

> @@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   	struct tree *new_tree;
>   
>   	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
> -	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
> +	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
> +		rollback_lock_file(&lock_file);
>   		return error(_("index file corrupt"));
> +	}
>   
>   	resolve_undo_clear_index(the_repository->index);
>   	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
> @@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   	} else {
>   		new_tree = repo_get_commit_tree(the_repository,
>   						new_branch_info->commit);
> -		if (!new_tree)
> +		if (!new_tree) {
> +			rollback_lock_file(&lock_file);
>   			return error(_("unable to read tree (%s)"),
>   				     oid_to_hex(&new_branch_info->commit->object.oid));
> +		}
>   	}
>   	if (opts->discard_changes) {
>   		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
> -		if (ret)
> +		if (ret) {
> +			rollback_lock_file(&lock_file);
>   			return ret;
> +		}
>   	} else {
>   		struct tree_desc trees[2];
>   		struct tree *tree;
> @@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
>   
>   		if (unmerged_index(the_repository->index)) {
> +			rollback_lock_file(&lock_file);
>   			error(_("you need to resolve your current index first"));
>   			return 1;

The changes up to here look like fixes for an existing bug and so would 
be better in a separate patch.

Sometimes we return "1" and sometimes "-1" what does that signal to the 
caller?

>   		}
> @@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   		ret = unpack_trees(2, trees, &topts);
>   		clear_unpack_trees_porcelain(&topts);
>   		if (ret == -1) {
> [lots of deletions]
> -			if (ret)
> -				return ret;
> +			rollback_lock_file(&lock_file);
> +			return 1;
>   		}
>   	}
>   
> @@ -1166,6 +1099,10 @@ static int switch_branches(const struct checkout_opts *opts,
>   	struct object_id rev;
>   	int flag, writeout_error = 0;
>   	int do_merge = 1;
> +	int created_autostash = 0;

This can be a bool

> +	struct strbuf old_commit_shortname = STRBUF_INIT;
> +	struct strbuf autostash_msg = STRBUF_INIT;
> +	const char *stash_label_base = NULL;
>   
>   	trace2_cmd_mode("branch");
>   
> @@ -1203,10 +1140,37 @@ static int switch_branches(const struct checkout_opts *opts,
>   			do_merge = 0;
>   	}
>   
> +	if (old_branch_info.name)
> +		stash_label_base = old_branch_info.name;
> +	else if (old_branch_info.commit) {
> +		strbuf_add_unique_abbrev(&old_commit_shortname,
> +					 &old_branch_info.commit->object.oid,
> +					 DEFAULT_ABBREV);
> +		stash_label_base = old_commit_shortname.buf;
> +	}
> +
>   	if (do_merge) {
>   		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> +		if (ret && opts->merge) {

As we saw above merge_working_tree() can return non-zero for a variety 
of reasons. We only want to try stashing if the call to unpack_trees() 
failed. Even then if you look at the list of errors in unpack-trees.h 
you'll see that only a few of them relate to problems that can be solved 
by stashing. The old code just tried merging whenever unpack_trees() 
failed so it probably not so bad to do the same here but we should not 
be stashing if merge_working_tree() returns before calling unpack_trees().

> +			strbuf_addf(&autostash_msg,
> +				    "autostash while switching to '%s'",
> +				    new_branch_info->name);
> +			create_autostash_ref_with_msg_silent(the_repository,
> +						   "CHECKOUT_AUTOSTASH_HEAD",

It's a shame we have to create a ref here. MERGE_AUTOSTASH exists so 
that "git merge --continue" can apply the stash once the user has 
resolved any merge conflicts. We don't have that problem here because 
there is no user interaction and we could just hold onto the stash oid 
in a variable.

> +						   autostash_msg.buf);
> +			created_autostash = 1;
> +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> +		}
>   		if (ret) {

I'm confused by this - if we stash then don't we expect the call to 
unpack_trees() in merge_working_tree() to succeed and therefore return 
0? If opts->merge is false then we should not be trying to apply the 
stash when merge_working_tree() fails.

> +			apply_autostash_ref_with_labels(the_repository,
> +						       "CHECKOUT_AUTOSTASH_HEAD",
> +						       new_branch_info->name,
> +						       "local",
> +						       stash_label_base,
> +						       autostash_msg.len ? autostash_msg.buf : NULL);

Can we create an autostash without setting a message in autostash_msg?

>   			branch_info_release(&old_branch_info);
> +			strbuf_release(&old_commit_shortname);
> +			strbuf_release(&autostash_msg);
>   			return ret;
>   		}
>   	}
> @@ -1216,8 +1180,31 @@ static int switch_branches(const struct checkout_opts *opts,
>   
>   	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
>   
> +	if (opts->conflict_style >= 0) {
> +		struct strbuf cfg = STRBUF_INIT;
> +		strbuf_addf(&cfg, "merge.conflictStyle=%s",
> +			    conflict_style_name(opts->conflict_style));
> +		git_config_push_parameter(cfg.buf);

This is rather unfortunate - it might be nicer for 
create_autostash_internal() to set the conflict style.

> +		strbuf_release(&cfg);
> +	}
> +	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
> +				       new_branch_info->name, "local",
> +				       stash_label_base,
> +				       autostash_msg.len ? autostash_msg.buf : NULL);
> +
> +	discard_index(the_repository->index);
> +	if (repo_read_index(the_repository) < 0)
> +		die(_("index file corrupt"));
> +
> +	if (created_autostash && !opts->discard_changes && !opts->quiet &&

Wouldn't it be a bug if we've created and autostash when 
opts->discard_changes is set? Why do we need to check it?

> +	    new_branch_info->commit)
> +		show_local_changes(&new_branch_info->commit->object,
> +				   &opts->diff_options);

So this is a change to the output when using "checkout -m"? If so it 
might be better as a separate change.


I'll have to leave it there for now, I'll try and look at the rest of 
the changes later in the week.

Thanks

Phillip

> +
>   	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
>   	branch_info_release(&old_branch_info);
> +	strbuf_release(&old_commit_shortname);
> +	strbuf_release(&autostash_msg);
>   
>   	return ret || writeout_error;
>   }
> diff --git a/sequencer.c b/sequencer.c
> index c2516000bd..b78a8ff092 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4770,15 +4770,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
>   		strvec_push(&store.args, stash_oid);
>   		if (run_command(&store))
>   			ret = error(_("cannot store %s"), stash_oid);
> +		else if (attempt_apply)
> +			fprintf(stderr,
> +				_("Your local changes are stashed, however, applying it to carry\n"
> +				  "forward your local changes resulted in conflicts:\n"
> +				  "\n"
> +				  " - You can try resolving them now.  If you resolved them\n"
> +				  "   successfully, discard the stash entry with \"git stash drop\".\n"
> +				  "\n"
> +				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
> +				  "   to deal with them right now, and later \"git stash pop\" to\n"
> +				  "   recover your local changes.\n"));
>   		else
>   			fprintf(stderr,
> -				_("%s\n"
> +				_("Autostash exists; creating a new stash entry.\n"
>   				  "Your changes are safe in the stash.\n"
>   				  "You can run \"git stash pop\" or"
> -				  " \"git stash drop\" at any time.\n"),
> -				attempt_apply ?
> -				_("Applying autostash resulted in conflicts.") :
> -				_("Autostash exists; creating a new stash entry."));
> +				  " \"git stash drop\" at any time.\n"));
>   	}
>   
>   	return ret;
> diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
> index ad3ba6a984..e4e2cb19ce 100755
> --- a/t/t3420-rebase-autostash.sh
> +++ b/t/t3420-rebase-autostash.sh
> @@ -61,18 +61,30 @@ create_expected_failure_apply () {
>   	First, rewinding head to replay your work on top of it...
>   	Applying: second commit
>   	Applying: third commit
> -	Applying autostash resulted in conflicts.
> -	Your changes are safe in the stash.
> -	You can run "git stash pop" or "git stash drop" at any time.
> +	Your local changes are stashed, however, applying it to carry
> +	forward your local changes resulted in conflicts:
> +
> +	 - You can try resolving them now.  If you resolved them
> +	   successfully, discard the stash entry with "git stash drop".
> +
> +	 - Alternatively you can "git reset --hard" if you do not want
> +	   to deal with them right now, and later "git stash pop" to
> +	   recover your local changes.
>   	EOF
>   }
>   
>   create_expected_failure_merge () {
>   	cat >expected <<-EOF
>   	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
> -	Applying autostash resulted in conflicts.
> -	Your changes are safe in the stash.
> -	You can run "git stash pop" or "git stash drop" at any time.
> +	Your local changes are stashed, however, applying it to carry
> +	forward your local changes resulted in conflicts:
> +
> +	 - You can try resolving them now.  If you resolved them
> +	   successfully, discard the stash entry with "git stash drop".
> +
> +	 - Alternatively you can "git reset --hard" if you do not want
> +	   to deal with them right now, and later "git stash pop" to
> +	   recover your local changes.
>   	Successfully rebased and updated refs/heads/rebased-feature-branch.
>   	EOF
>   }
> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..c474c6759f 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -210,6 +210,214 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
>   	test_cmp expect two
>   '
>   
> +test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	fill a b X d e >two &&
> +	git checkout --merge --conflict=zdiff3 simple &&
> +
> +	cat <<-EOF >expect &&
> +	a
> +	<<<<<<< simple
> +	c
> +	||||||| main
> +	b
> +	c
> +	d
> +	=======
> +	b
> +	X
> +	d
> +	>>>>>>> local
> +	e
> +	EOF
> +	test_cmp expect two
> +'
> +
> +test_expect_success 'checkout -m respects merge.conflictStyle config' '
> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	test_config merge.conflictStyle diff3 &&
> +	fill b d >two &&
> +	git checkout -m simple &&
> +
> +	cat <<-EOF >expect &&
> +	<<<<<<< simple
> +	a
> +	c
> +	e
> +	||||||| main
> +	a
> +	b
> +	c
> +	d
> +	e
> +	=======
> +	b
> +	d
> +	>>>>>>> local
> +	EOF
> +	test_cmp expect two
> +'
> +
> +test_expect_success 'checkout -m skips stash when no conflict' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git stash list >stash-before &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	git stash list >stash-after &&
> +	test_cmp stash-before stash-after &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same
> +'
> +
> +test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git add same &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same
> +'
> +
> +test_expect_success 'checkout -m stashes and applies on conflicting changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 6 7 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "Applied autostash" actual &&
> +	fill 1 2 3 4 5 6 7 >expect &&
> +	test_cmp expect one
> +'
> +
> +test_expect_success 'checkout -m with mixed staged and unstaged changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git add same &&
> +	fill 1 2 3 4 5 6 7 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "Applied autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same &&
> +	fill 1 2 3 4 5 6 7 >expect &&
> +	test_cmp expect one
> +'
> +
> +test_expect_success 'checkout -m stashes on truly conflicting changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	test_must_fail git checkout side 2>stderr &&
> +	test_grep "Your local changes" stderr &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "resulted in conflicts" actual &&
> +	test_grep "git stash drop" actual &&
> +	git stash drop &&
> +	git reset --hard
> +'
> +
> +test_expect_success 'checkout -m produces usable stash on conflict' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep "recover your local changes" actual &&
> +	git checkout -f main &&
> +	git stash pop &&
> +	fill 1 2 3 4 5 >expect &&
> +	test_cmp expect one
> +'
> +
> +test_expect_success 'checkout -m autostash message includes target branch' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	git stash list >stash-list &&
> +	test_grep "autostash while switching to .side." stash-list &&
> +	git stash drop &&
> +	git checkout -f main &&
> +	git reset --hard
> +'
> +
> +test_expect_success 'checkout -m stashes on staged conflicting changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	git add one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "resulted in conflicts" actual &&
> +	test_grep "git stash drop" actual &&
> +	git stash drop &&
> +	git reset --hard
> +'
> +
> +test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	git checkout -b nonoverlap_base &&
> +	fill a b c d >file &&
> +	git add file &&
> +	git commit -m "add file" &&
> +
> +	git checkout -b nonoverlap_child &&
> +	fill a b c INSERTED d >file &&
> +	git commit -a -m "insert line near end of file" &&
> +
> +	fill DIRTY a b c INSERTED d >file &&
> +
> +	git stash list >stash-before &&
> +	git checkout -m nonoverlap_base 2>stderr &&
> +	test_grep "Applied autostash" stderr &&
> +	test_grep ! "resulted in conflicts" stderr &&
> +
> +	git stash list >stash-after &&
> +	test_cmp stash-before stash-after &&
> +
> +	fill DIRTY a b c d >expect &&
> +	test_cmp expect file &&
> +
> +	git checkout -f main &&
> +	git branch -D nonoverlap_base &&
> +	git branch -D nonoverlap_child
> +'
> +
> +test_expect_success 'checkout -m -b skips stash with dirty tree' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git checkout -m -b newbranch >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same &&
> +	git checkout main &&
> +	git branch -D newbranch
> +'
> +
>   test_expect_success 'switch to another branch while carrying a deletion' '
>   	git checkout -f main &&
>   	git reset --hard &&
> diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
> index 9838094b66..cbef8a534e 100755
> --- a/t/t7600-merge.sh
> +++ b/t/t7600-merge.sh
> @@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
>   	git diff >expect &&
>   	test_when_finished "test_might_fail git stash drop" &&
>   	git merge --autostash c3 2>err &&
> -	test_grep "Applying autostash resulted in conflicts." err &&
> +	test_grep "your local changes resulted in conflicts" err &&
>   	git show HEAD:file >merge-result &&
>   	test_cmp result.1-9 merge-result &&
>   	git stash show -p >actual &&
> diff --git a/xdiff-interface.c b/xdiff-interface.c
> index f043330f2a..5ee2b96d0a 100644
> --- a/xdiff-interface.c
> +++ b/xdiff-interface.c
> @@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
>   		return -1;
>   }
>   
> +const char *conflict_style_name(int style)
> +{
> +	switch (style) {
> +	case XDL_MERGE_DIFF3:
> +		return "diff3";
> +	case XDL_MERGE_ZEALOUS_DIFF3:
> +		return "zdiff3";
> +	default:
> +		return "merge";
> +	}
> +}
> +
>   int git_xmerge_style = -1;
>   
>   int git_xmerge_config(const char *var, const char *value,
> diff --git a/xdiff-interface.h b/xdiff-interface.h
> index fbc4ceec40..ce54e1c0e0 100644
> --- a/xdiff-interface.h
> +++ b/xdiff-interface.h
> @@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
>   void xdiff_clear_find_func(xdemitconf_t *xecfg);
>   struct config_context;
>   int parse_conflict_style_name(const char *value);
> +const char *conflict_style_name(int style);
>   int git_xmerge_config(const char *var, const char *value,
>   		      const struct config_context *ctx, void *cb);
>   extern int git_xmerge_style;

Re: [PATCH v12 4/4] checkout: -m (--merge) uses autostash when switching branches

[Junio C Hamano]

Phillip Wood <phillip.wood123@gmail.com> writes:

> Hi Harald
>
> For the subject line I think
>
>      checkout -m: autostash when switching branches
>
> would be more in keeping with our usual style.

Thanks.  I agree.  Alternatively, 

    checkout: autostash when switching branches with -m

would also work.

>> When switching branches with "git checkout -m", local modifications
>> can block the switch. 
>
> Really? Isn't the point of "checkout -m" to merge the local 
> modifications into the branch that's being checked out?

Yeah, either "git checkout -m" -> "git checkout" (without "-m")
or "can block" -> "can cause conflict during".  Also, I think a bit
more description of what happens in the current system without this
patch series would clarify the motivation.  Perhaps something like...

    When switching branches with "git checkout -m", the attempted
    merge of local modifications may cause conflicts with the
    changes made on the other branch, which the user may not want to
    (or may not be able to) resolve right now.  Because there is no
    easy way to recover from this situation, we discouraged users from
    using "checkout -m" unless they are certain their changes are
    trivial and within their ability to resolve conflicts.

... would contrast well with "the user can resolve or reset and
postpone 'stash pop' to some later time" we will give at the end of
the message.

>> Teach the -m flow to create a temporary stash
>> before switching and reapply it after.  On success, only "Applied
>> autostash." is shown. 
>
> and a diff of the local changes?

I noticed that we show the same output as a successful "git checkout
other-branch" without "-m" shows, i.e., short list of modified
paths.  I am not sure what it is officially called but calling it
"diff" is probably misleading.

>> If reapplying causes conflicts, the stash is
>> kept and the user is told they can resolve and run "git stash drop",
>> or run "git reset --hard" and later "git stash pop" to recover their
>> changes.

Good.

>> @@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
>>   		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
>>   
>>   		if (unmerged_index(the_repository->index)) {
>> +			rollback_lock_file(&lock_file);
>>   			error(_("you need to resolve your current index first"));
>>   			return 1;
>
> The changes up to here look like fixes for an existing bug and so would 
> be better in a separate patch.

Good point.

> Sometimes we return "1" and sometimes "-1" what does that signal to the 
> caller?

This too.

>> @@ -846,82 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
>>   		ret = unpack_trees(2, trees, &topts);
>>   		clear_unpack_trees_porcelain(&topts);
>>   		if (ret == -1) {
>> [lots of deletions]
>> -			if (ret)
>> -				return ret;
>> +			rollback_lock_file(&lock_file);
>> +			return 1;
>>   		}
>>   	}
>>   
>> @@ -1166,6 +1099,10 @@ static int switch_branches(const struct checkout_opts *opts,
>>   	struct object_id rev;
>>   	int flag, writeout_error = 0;
>>   	int do_merge = 1;
>> +	int created_autostash = 0;
>
> This can be a bool

So are many things (like do_merge, writeout_error).  I wouldn't
worry too much about the difference between int and bool unless it
is a function parameter.

>> +			strbuf_addf(&autostash_msg,
>> +				    "autostash while switching to '%s'",
>> +				    new_branch_info->name);
>> +			create_autostash_ref_with_msg_silent(the_repository,
>> +						   "CHECKOUT_AUTOSTASH_HEAD",
>
> It's a shame we have to create a ref here. MERGE_AUTOSTASH exists so 
> that "git merge --continue" can apply the stash once the user has 
> resolved any merge conflicts. We don't have that problem here because 
> there is no user interaction and we could just hold onto the stash oid 
> in a variable.

Hmph, so it is not a shame and we can do without it?

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> The changes up to here look like fixes for an existing bug and so would 
> be better in a separate patch.

👍

> Sometimes we return "1" and sometimes "-1" what does that signal to the 
> caller?

I just tried to follow a pattern, I'm not knowlegable of how this return code will be used. Futher down in the file we check 'ret == -1' and turn it into 1, so maybe 1 is correct?

> > +                                                    autostash_msg.len ? autostash_msg.buf : NULL);
> 
> Can we create an autostash without setting a message in autostash_msg?

No, seems not. I'll simplify it!

> > +     if (created_autostash && !opts->discard_changes && !opts->quiet &&
> 
> Wouldn't it be a bug if we've created and autostash when
> opts->discard_changes is set? Why do we need to check it?

I'll simplify it!

> > +	    new_branch_info->commit)
> > +		show_local_changes(&new_branch_info->commit->object,
> > +				   &opts->diff_options);
>
> So this is a change to the output when using "checkout -m"? If so it 
> might be better as a separate change.

Do you mean to drop if from my patchset, or just make it a separate
commit within this series?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Phillip Wood]

On 14/04/2026 21:06, Harald Nordgren wrote:
>> The changes up to here look like fixes for an existing bug and so would
>> be better in a separate patch.
> 
> 👍
> 
>> Sometimes we return "1" and sometimes "-1" what does that signal to the
>> caller?
> 
> I just tried to follow a pattern, I'm not knowlegable of how this return
 > code will be used. Futher down in the file we check 'ret == -1' and
 > turn it into 1, so maybe 1 is correct?

But you can read the code to see how it is used. Tracing the return path 
of merge_working_tree(), the return value get propagated back up to the 
top of the call stack i.e. cmd_checkout() or cmd_switch() and used as 
the return value there. I had wondered if we were using the value on the 
way back up the stack and doing something different based on the whether 
it was "1" or "-1" but we don't so it only affects the exit code of "git 
checkout". That means returning "1" is sensible I think.

> Do you mean to drop if from my patchset, or just make it a separate
> commit within this series?

A separate commit in this series. As "git checkout" without "-m" can 
also carry local changes across we probably should do the same there as 
well.

Thanks

Phillip

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> > +                     strbuf_addf(&autostash_msg,
> > +                                 "autostash while switching to '%s'",
> > +                                 new_branch_info->name);
> > +                     create_autostash_ref_with_msg_silent(the_repository,
> > +                                                "CHECKOUT_AUTOSTASH_HEAD",
> 
> It's a shame we have to create a ref here. MERGE_AUTOSTASH exists so
> that "git merge --continue" can apply the stash once the user has
> resolved any merge conflicts. We don't have that problem here because
> there is no user interaction and we could just hold onto the stash oid
> in a variable.

I don't know how to actually do that. Maybe better to do later?

> > +                                                autostash_msg.buf);
> > +                     created_autostash = 1;
> > +                     ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> > +             }
> >               if (ret) {
> 
> I'm confused by this - if we stash then don't we expect the call to
> unpack_trees() in merge_working_tree() to succeed and therefore return
> 0? If opts->merge is false then we should not be trying to apply the
> stash when merge_working_tree() fails.

Same here, I'm not sure how to get this to work. Maybe better to do later?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> > > +                     strbuf_addf(&autostash_msg,
> > > +                                 "autostash while switching to '%s'",
> > > +                                 new_branch_info->name);
> > > +                     create_autostash_ref_with_msg_silent(the_repository,
> > > +                                                "CHECKOUT_AUTOSTASH_HEAD",
> > 
> > It's a shame we have to create a ref here. MERGE_AUTOSTASH exists so
> > that "git merge --continue" can apply the stash once the user has
> > resolved any merge conflicts. We don't have that problem here because
> > there is no user interaction and we could just hold onto the stash oid
> > in a variable.
> 
> I don't know how to actually do that. Maybe better to do later?

A gave this a try, but it becomes a very big change. Or maybe I'm missing
some key knowledge here.

> > > +                                                autostash_msg.buf);
> > > +                     created_autostash = 1;
> > > +                     ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> > > +             }
> > >               if (ret) {
> > 
> > I'm confused by this - if we stash then don't we expect the call to
> > unpack_trees() in merge_working_tree() to succeed and therefore return
> > 0? If opts->merge is false then we should not be trying to apply the
> > stash when merge_working_tree() fails.
> 
> Same here, I'm not sure how to get this to work. Maybe better to do later?

I think I succeeded with this one.


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Phillip Wood]

On 15/04/2026 09:19, Harald Nordgren wrote:
>>>> +                     strbuf_addf(&autostash_msg,
>>>> +                                 "autostash while switching to '%s'",
>>>> +                                 new_branch_info->name);
>>>> +                     create_autostash_ref_with_msg_silent(the_repository,
>>>> +                                                "CHECKOUT_AUTOSTASH_HEAD",
>>>
>>> It's a shame we have to create a ref here. MERGE_AUTOSTASH exists so
>>> that "git merge --continue" can apply the stash once the user has
>>> resolved any merge conflicts. We don't have that problem here because
>>> there is no user interaction and we could just hold onto the stash oid
>>> in a variable.
>>
>> I don't know how to actually do that. Maybe better to do later?
> 
> A gave this a try, but it becomes a very big change. Or maybe I'm missing
> some key knowledge here.

Maybe leave that for now then

>>>> +                                                autostash_msg.buf);
>>>> +                     created_autostash = 1;
>>>> +                     ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>>>> +             }
>>>>                if (ret) {
>>>
>>> I'm confused by this - if we stash then don't we expect the call to
>>> unpack_trees() in merge_working_tree() to succeed and therefore return
>>> 0? 

In that case we apply the stash lower down so that's fine.

>>> If opts->merge is false then we should not be trying to apply the
>>> stash when merge_working_tree() fails.
>>
>> Same here, I'm not sure how to get this to work. Maybe better to do later?
> 
> I think I succeeded with this one.

This one definitely needs fixing but it should be simple to do as I 
think it is just a logic error. We should not be trying to re-apply the 
stash unless we created it and we can check "created_autostash" to do that.

Thanks

Phillip

> 
> 
> Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> > +	if (old_branch_info.name)
> > +		stash_label_base = old_branch_info.name;
> > +	else if (old_branch_info.commit) {
> > +		strbuf_add_unique_abbrev(&old_commit_shortname,
> > +					 &old_branch_info.commit->object.oid,
> > +					 DEFAULT_ABBREV);
> > +		stash_label_base = old_commit_shortname.buf;
> > +	}
> > +
> >   	if (do_merge) {
> >   		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> > +		if (ret && opts->merge) {
> 
> As we saw above merge_working_tree() can return non-zero for a variety 
> of reasons. We only want to try stashing if the call to unpack_trees() 
> failed. Even then if you look at the list of errors in unpack-trees.h 
> you'll see that only a few of them relate to problems that can be solved 
> by stashing. The old code just tried merging whenever unpack_trees() 
> failed so it probably not so bad to do the same here but we should not 
> be stashing if merge_working_tree() returns before calling unpack_trees().

What you are saying makes a lot of sense.

I gave this a shot now, trying to return an error code that only attempts
the stashing when it has a chance of improving the outcome. Not at all sure
if it's correct though!

> > +						   autostash_msg.buf);
> > +			created_autostash = 1;
> > +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> > +		}
> >   		if (ret) {
> 
> I'm confused by this - if we stash then don't we expect the call to 
> unpack_trees() in merge_working_tree() to succeed and therefore return 
> 0? If opts->merge is false then we should not be trying to apply the 
> stash when merge_working_tree() fails.

I'm attempting to fix this by making call to apply_autostash_ref
conditional on whether or not the autostash was actually created. Makes
sense?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Phillip Wood]

On 15/04/2026 09:16, Harald Nordgren wrote:
>>> +	if (old_branch_info.name)
>>> +		stash_label_base = old_branch_info.name;
>>> +	else if (old_branch_info.commit) {
>>> +		strbuf_add_unique_abbrev(&old_commit_shortname,
>>> +					 &old_branch_info.commit->object.oid,
>>> +					 DEFAULT_ABBREV);
>>> +		stash_label_base = old_commit_shortname.buf;
>>> +	}
>>> +
>>>    	if (do_merge) {
>>>    		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>>> +		if (ret && opts->merge) {
>>
>> As we saw above merge_working_tree() can return non-zero for a variety
>> of reasons. We only want to try stashing if the call to unpack_trees()
>> failed. Even then if you look at the list of errors in unpack-trees.h
>> you'll see that only a few of them relate to problems that can be solved
>> by stashing. The old code just tried merging whenever unpack_trees()
>> failed so it probably not so bad to do the same here but we should not
>> be stashing if merge_working_tree() returns before calling unpack_trees().
> 
> What you are saying makes a lot of sense.
> 
> I gave this a shot now, trying to return an error code that only attempts
> the stashing when it has a chance of improving the outcome. Not at all sure
> if it's correct though!

That sounds like the right approach

>>> +						   autostash_msg.buf);
>>> +			created_autostash = 1;
>>> +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>>> +		}
>>>    		if (ret) {
>>
>> I'm confused by this - if we stash then don't we expect the call to
>> unpack_trees() in merge_working_tree() to succeed and therefore return
>> 0? If opts->merge is false then we should not be trying to apply the
>> stash when merge_working_tree() fails.
> 
> I'm attempting to fix this by making call to apply_autostash_ref
> conditional on whether or not the autostash was actually created. Makes
> sense?

Yes, exactly

Thanks

Phillip

Re: [PATCH v12 0/4] checkout: 'autostash' for branch switching

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> Harald Nordgren (4):
>   stash: add --label-ours, --label-theirs, --label-base for apply
>   sequencer: allow create_autostash to run silently
>   sequencer: teach autostash apply to take optional conflict marker
>     labels
>   checkout: -m (--merge) uses autostash when switching branches
>
>  Documentation/git-checkout.adoc |  58 ++++-----
>  Documentation/git-stash.adoc    |  11 +-
>  Documentation/git-switch.adoc   |  33 ++---
>  builtin/checkout.c              | 147 ++++++++++------------
>  builtin/stash.c                 |  32 +++--
>  sequencer.c                     |  81 ++++++++++---
>  sequencer.h                     |   6 +
>  t/t3420-rebase-autostash.sh     |  24 +++-
>  t/t3903-stash.sh                |  29 +++++
>  t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
>  t/t7600-merge.sh                |   2 +-
>  xdiff-interface.c               |  12 ++
>  xdiff-interface.h               |   1 +
>  xdiff/xmerge.c                  |   6 +-
>  14 files changed, 491 insertions(+), 159 deletions(-)

I am not taking v11 and v12 today, as v10 is already in 'next', but
for future reference, I have to say that this cover letter is not
very helpful.

It shows 350+ lines of range-diff to show mostly irrelevant noise,
when the true difference between v11 and v12 is only that two helper
functions create_autostash_ref_silent{,_with_msg}() are merged into
one create_autostash_ref_with_msg_silent() helper function.

It is much easier to read that read from the diff between the
results of applying v11 and v12 on the same base commit, which is a
mere 55 lines (shown at the end).

I would not expect you to teach GGG to produce a better range-diff
or add an option to instead show an interdiff, but doesn't GGG
already have a way to add some human-written comment, e.g.,

    Changes since v11:

        Two helper functions create_autostash_ref_silent{,_with_msg}()
        are merged into one create_autostash_ref_with_msg_silent().

to the cover letter?  Such a comment, even a very short one like I
showed above, would be a lot more effective way to help human
readers to decide what is the point of this iteration is, especially
when you are sending v11 and v12 almost back-to-back, and to decide
if it is easier to understand to read both or if v11 can be skipped
and reading v12 alone (with the understanding of the difference
explained in the comment) should be enough to tell if v12 is an
improvement over v11 or not.

https://github.com/gitgitgadget/gitgitgadget/blob/main/DESIGN.md#patch-submissions

says that

    The description of the Pull Request will be used as cover
    letter, ...

so perhaps your pull-request comment should have something more than
just the list of CC: recipients?

Thanks.


diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2adfefa085..a7a93e1c6b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1155,9 +1155,9 @@ static int switch_branches(const struct checkout_opts *opts,
 			strbuf_addf(&autostash_msg,
 				    "autostash while switching to '%s'",
 				    new_branch_info->name);
-			create_autostash_ref_silent_with_msg(the_repository,
-							    "CHECKOUT_AUTOSTASH_HEAD",
-							    autostash_msg.buf);
+			create_autostash_ref_with_msg_silent(the_repository,
+						   "CHECKOUT_AUTOSTASH_HEAD",
+						   autostash_msg.buf);
 			created_autostash = 1;
 			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 		}
diff --git a/sequencer.c b/sequencer.c
index febdb5b20a..b78a8ff092 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4726,14 +4726,8 @@ void create_autostash_ref(struct repository *r, const char *refname)
 	create_autostash_internal(r, NULL, refname, NULL, false);
 }
 
-void create_autostash_ref_silent(struct repository *r, const char *refname)
-{
-	create_autostash_internal(r, NULL, refname, NULL, true);
-}
-
-void create_autostash_ref_silent_with_msg(struct repository *r,
-					  const char *refname,
-					  const char *message)
+void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
+				 const char *message)
 {
 	create_autostash_internal(r, NULL, refname, message, true);
 }
diff --git a/sequencer.h b/sequencer.h
index 67de755053..b0c891d3b6 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -230,10 +230,8 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path);
 void create_autostash_ref(struct repository *r, const char *refname);
-void create_autostash_ref_silent(struct repository *r, const char *refname);
-void create_autostash_ref_silent_with_msg(struct repository *r,
-					  const char *refname,
-					  const char *message);
+void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
+				 const char *message);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);


> base-commit: 9e8f4e9c04e3efa494e78b710e0c5f6cc77a0a5e
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v12
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v12
> Pull-Request: https://github.com/git/git/pull/2234
>
> Range-diff vs v11:
>
>  1:  9ab5431b47 = 1:  9ab5431b47 stash: add --label-ours, --label-theirs, --label-base for apply
>  2:  e7f8328e3c ! 2:  e11a622bdf sequencer: allow create_autostash to run silently
>      @@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list,
>        				      const char *path,
>       -				      const char *refname)
>       +				      const char *refname,
>      ++				      const char *message,
>       +				      bool silent)
>        {
>        	struct strbuf buf = STRBUF_INIT;
>        	struct lock_file lock_file = LOCK_INIT;
>      +@@ sequencer.c: static void create_autostash_internal(struct repository *r,
>      + 		struct object_id oid;
>      + 
>      + 		strvec_pushl(&stash.args,
>      +-			     "stash", "create", "autostash", NULL);
>      ++			     "stash", "create",
>      ++			     message ? message : "autostash", NULL);
>      + 		stash.git_cmd = 1;
>      + 		stash.no_stdin = 1;
>      + 		strbuf_reset(&buf);
>       @@ sequencer.c: static void create_autostash_internal(struct repository *r,
>        					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
>        		}
>      @@ sequencer.c: static void create_autostash_internal(struct repository *r,
>        void create_autostash(struct repository *r, const char *path)
>        {
>       -	create_autostash_internal(r, path, NULL);
>      -+	create_autostash_internal(r, path, NULL, false);
>      ++	create_autostash_internal(r, path, NULL, NULL, false);
>        }
>        
>        void create_autostash_ref(struct repository *r, const char *refname)
>        {
>       -	create_autostash_internal(r, NULL, refname);
>      -+	create_autostash_internal(r, NULL, refname, false);
>      ++	create_autostash_internal(r, NULL, refname, NULL, false);
>       +}
>       +
>      -+void create_autostash_ref_silent(struct repository *r, const char *refname)
>      ++void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
>      ++				 const char *message)
>       +{
>      -+	create_autostash_internal(r, NULL, refname, true);
>      ++	create_autostash_internal(r, NULL, refname, message, true);
>        }
>        
>        static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
>      @@ sequencer.h: void commit_post_rewrite(struct repository *r,
>        
>        void create_autostash(struct repository *r, const char *path);
>        void create_autostash_ref(struct repository *r, const char *refname);
>      -+void create_autostash_ref_silent(struct repository *r, const char *refname);
>      ++void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
>      ++				 const char *message);
>        int save_autostash(const char *path);
>        int save_autostash_ref(struct repository *r, const char *refname);
>        int apply_autostash(const char *path);
>  3:  3242fd3261 ! 3:  4593745e90 sequencer: teach autostash apply to take optional conflict marker labels
>      @@ Commit message
>           Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
>       
>        ## sequencer.c ##
>      -@@ sequencer.c: void create_autostash_ref_silent(struct repository *r, const char *refname)
>      - 	create_autostash_internal(r, NULL, refname, true);
>      +@@ sequencer.c: void create_autostash_ref_with_msg_silent(struct repository *r, const char *refn
>      + 	create_autostash_internal(r, NULL, refname, message, true);
>        }
>        
>       -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
>       +static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
>       +				    const char *label_ours, const char *label_theirs,
>      -+				    const char *label_base)
>      ++				    const char *label_base,
>      ++				    const char *stash_msg)
>        {
>        	struct child_process child = CHILD_PROCESS_INIT;
>        	int ret = 0;
>      @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
>        		strvec_push(&child.args, stash_oid);
>        		ret = run_command(&child);
>        	}
>      +@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
>      + 		strvec_push(&store.args, "stash");
>      + 		strvec_push(&store.args, "store");
>      + 		strvec_push(&store.args, "-m");
>      +-		strvec_push(&store.args, "autostash");
>      ++		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
>      + 		strvec_push(&store.args, "-q");
>      + 		strvec_push(&store.args, stash_oid);
>      + 		if (run_command(&store))
>       @@ sequencer.c: static int apply_save_autostash(const char *path, int attempt_apply)
>        	}
>        	strbuf_trim(&stash_oid);
>        
>       -	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
>       +	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
>      -+				      NULL, NULL, NULL);
>      ++				      NULL, NULL, NULL, NULL);
>        
>        	unlink(path);
>        	strbuf_release(&stash_oid);
>      @@ sequencer.c: int apply_autostash(const char *path)
>        int apply_autostash_oid(const char *stash_oid)
>        {
>       -	return apply_save_autostash_oid(stash_oid, 1);
>      -+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
>      ++	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
>        }
>        
>        static int apply_save_autostash_ref(struct repository *r, const char *refname,
>       -				    int attempt_apply)
>       +				    int attempt_apply,
>       +				    const char *label_ours, const char *label_theirs,
>      -+				    const char *label_base)
>      ++				    const char *label_base,
>      ++				    const char *stash_msg)
>        {
>        	struct object_id stash_oid;
>        	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
>      @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
>        	oid_to_hex_r(stash_oid_hex, &stash_oid);
>       -	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
>       +	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
>      -+				       label_ours, label_theirs, label_base);
>      ++				       label_ours, label_theirs, label_base,
>      ++				       stash_msg);
>        
>        	refs_delete_ref(get_main_ref_store(r), "", refname,
>        			&stash_oid, REF_NO_DEREF);
>      @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
>        int save_autostash_ref(struct repository *r, const char *refname)
>        {
>       -	return apply_save_autostash_ref(r, refname, 0);
>      -+	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
>      ++	return apply_save_autostash_ref(r, refname, 0,
>      ++					NULL, NULL, NULL, NULL);
>        }
>        
>        int apply_autostash_ref(struct repository *r, const char *refname)
>        {
>       -	return apply_save_autostash_ref(r, refname, 1);
>      -+	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
>      ++	return apply_save_autostash_ref(r, refname, 1,
>      ++					NULL, NULL, NULL, NULL);
>       +}
>       +
>       +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
>       +				    const char *label_ours, const char *label_theirs,
>      -+				    const char *label_base)
>      ++				    const char *label_base,
>      ++				    const char *stash_msg)
>       +{
>       +	return apply_save_autostash_ref(r, refname, 1,
>      -+					label_ours, label_theirs, label_base);
>      ++					label_ours, label_theirs, label_base,
>      ++					stash_msg);
>        }
>        
>        static int checkout_onto(struct repository *r, struct replay_opts *opts,
>      @@ sequencer.h: int save_autostash_ref(struct repository *r, const char *refname);
>        int apply_autostash_ref(struct repository *r, const char *refname);
>       +int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
>       +				    const char *label_ours, const char *label_theirs,
>      -+				    const char *label_base);
>      ++				    const char *label_base,
>      ++				    const char *stash_msg);
>        
>        #define SUMMARY_INITIAL_COMMIT   (1 << 0)
>        #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
>  4:  97a5d87c81 ! 4:  911e520431 checkout: -m (--merge) uses autostash when switching branches
>      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>       +			strbuf_addf(&autostash_msg,
>       +				    "autostash while switching to '%s'",
>       +				    new_branch_info->name);
>      -+			create_autostash_ref_silent_with_msg(the_repository,
>      -+							    "CHECKOUT_AUTOSTASH_HEAD",
>      -+							    autostash_msg.buf);
>      ++			create_autostash_ref_with_msg_silent(the_repository,
>      ++						   "CHECKOUT_AUTOSTASH_HEAD",
>      ++						   autostash_msg.buf);
>       +			created_autostash = 1;
>       +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>       +		}
>      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>        }
>       
>        ## sequencer.c ##
>      -@@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list, int offset)
>      - static void create_autostash_internal(struct repository *r,
>      - 				      const char *path,
>      - 				      const char *refname,
>      -+				      const char *message,
>      - 				      bool silent)
>      - {
>      - 	struct strbuf buf = STRBUF_INIT;
>      -@@ sequencer.c: static void create_autostash_internal(struct repository *r,
>      - 		struct object_id oid;
>      - 
>      - 		strvec_pushl(&stash.args,
>      --			     "stash", "create", "autostash", NULL);
>      -+			     "stash", "create",
>      -+			     message ? message : "autostash", NULL);
>      - 		stash.git_cmd = 1;
>      - 		stash.no_stdin = 1;
>      - 		strbuf_reset(&buf);
>      -@@ sequencer.c: static void create_autostash_internal(struct repository *r,
>      - 
>      - void create_autostash(struct repository *r, const char *path)
>      - {
>      --	create_autostash_internal(r, path, NULL, false);
>      -+	create_autostash_internal(r, path, NULL, NULL, false);
>      - }
>      - 
>      - void create_autostash_ref(struct repository *r, const char *refname)
>      - {
>      --	create_autostash_internal(r, NULL, refname, false);
>      -+	create_autostash_internal(r, NULL, refname, NULL, false);
>      - }
>      - 
>      - void create_autostash_ref_silent(struct repository *r, const char *refname)
>      - {
>      --	create_autostash_internal(r, NULL, refname, true);
>      -+	create_autostash_internal(r, NULL, refname, NULL, true);
>      -+}
>      -+
>      -+void create_autostash_ref_silent_with_msg(struct repository *r,
>      -+					  const char *refname,
>      -+					  const char *message)
>      -+{
>      -+	create_autostash_internal(r, NULL, refname, message, true);
>      - }
>      - 
>      - static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
>      - 				    const char *label_ours, const char *label_theirs,
>      --				    const char *label_base)
>      -+				    const char *label_base,
>      -+				    const char *stash_msg)
>      - {
>      - 	struct child_process child = CHILD_PROCESS_INIT;
>      - 	int ret = 0;
>       @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
>      - 		strvec_push(&store.args, "stash");
>      - 		strvec_push(&store.args, "store");
>      - 		strvec_push(&store.args, "-m");
>      --		strvec_push(&store.args, "autostash");
>      -+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
>      - 		strvec_push(&store.args, "-q");
>        		strvec_push(&store.args, stash_oid);
>        		if (run_command(&store))
>        			ret = error(_("cannot store %s"), stash_oid);
>      @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
>        	}
>        
>        	return ret;
>      -@@ sequencer.c: static int apply_save_autostash(const char *path, int attempt_apply)
>      - 	strbuf_trim(&stash_oid);
>      - 
>      - 	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
>      --				      NULL, NULL, NULL);
>      -+				      NULL, NULL, NULL, NULL);
>      - 
>      - 	unlink(path);
>      - 	strbuf_release(&stash_oid);
>      -@@ sequencer.c: int apply_autostash(const char *path)
>      - 
>      - int apply_autostash_oid(const char *stash_oid)
>      - {
>      --	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL);
>      -+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
>      - }
>      - 
>      - static int apply_save_autostash_ref(struct repository *r, const char *refname,
>      - 				    int attempt_apply,
>      - 				    const char *label_ours, const char *label_theirs,
>      --				    const char *label_base)
>      -+				    const char *label_base,
>      -+				    const char *stash_msg)
>      - {
>      - 	struct object_id stash_oid;
>      - 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
>      -@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
>      - 
>      - 	oid_to_hex_r(stash_oid_hex, &stash_oid);
>      - 	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
>      --				       label_ours, label_theirs, label_base);
>      -+				       label_ours, label_theirs, label_base,
>      -+				       stash_msg);
>      - 
>      - 	refs_delete_ref(get_main_ref_store(r), "", refname,
>      - 			&stash_oid, REF_NO_DEREF);
>      -@@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const char *refname,
>      - 
>      - int save_autostash_ref(struct repository *r, const char *refname)
>      - {
>      --	return apply_save_autostash_ref(r, refname, 0, NULL, NULL, NULL);
>      -+	return apply_save_autostash_ref(r, refname, 0,
>      -+					NULL, NULL, NULL, NULL);
>      - }
>      - 
>      - int apply_autostash_ref(struct repository *r, const char *refname)
>      - {
>      --	return apply_save_autostash_ref(r, refname, 1, NULL, NULL, NULL);
>      -+	return apply_save_autostash_ref(r, refname, 1,
>      -+					NULL, NULL, NULL, NULL);
>      - }
>      - 
>      - int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
>      - 				    const char *label_ours, const char *label_theirs,
>      --				    const char *label_base)
>      -+				    const char *label_base,
>      -+				    const char *stash_msg)
>      - {
>      - 	return apply_save_autostash_ref(r, refname, 1,
>      --					label_ours, label_theirs, label_base);
>      -+					label_ours, label_theirs, label_base,
>      -+					stash_msg);
>      - }
>      - 
>      - static int checkout_onto(struct repository *r, struct replay_opts *opts,
>      -
>      - ## sequencer.h ##
>      -@@ sequencer.h: void commit_post_rewrite(struct repository *r,
>      - void create_autostash(struct repository *r, const char *path);
>      - void create_autostash_ref(struct repository *r, const char *refname);
>      - void create_autostash_ref_silent(struct repository *r, const char *refname);
>      -+void create_autostash_ref_silent_with_msg(struct repository *r,
>      -+					  const char *refname,
>      -+					  const char *message);
>      - int save_autostash(const char *path);
>      - int save_autostash_ref(struct repository *r, const char *refname);
>      - int apply_autostash(const char *path);
>      -@@ sequencer.h: int apply_autostash_oid(const char *stash_oid);
>      - int apply_autostash_ref(struct repository *r, const char *refname);
>      - int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
>      - 				    const char *label_ours, const char *label_theirs,
>      --				    const char *label_base);
>      -+				    const char *label_base,
>      -+				    const char *stash_msg);
>      - 
>      - #define SUMMARY_INITIAL_COMMIT   (1 << 0)
>      - #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
>       
>        ## t/t3420-rebase-autostash.sh ##
>       @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

>    The description of the Pull Request will be used as cover
>    letter, ...
>
> so perhaps your pull-request comment should have something more than
> just the list of CC: recipients?

I'll give it a try!


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Harald Nordgren <haraldnordgren@gmail.com> writes:

>>    The description of the Pull Request will be used as cover
>>    letter, ...
>>
>> so perhaps your pull-request comment should have something more than
>> just the list of CC: recipients?
>
> I'll give it a try!

;-)

I find that many topics by Patrick Steinhardt and Jeff King with
multiple iterations often come with good cover letters that outline
updates between iterations.

Thanks.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> It shows 350+ lines of range-diff to show mostly irrelevant noise,
> when the true difference between v11 and v12 is only that two helper
> functions create_autostash_ref_silent{,_with_msg}() are merged into
> one create_autostash_ref_with_msg_silent() helper function.
> 
> It is much easier to read that read from the diff between the
> results of applying v11 and v12 on the same base commit, which is a
> mere 55 lines (shown at the end).
> 
> I would not expect you to teach GGG to produce a better range-diff
> or add an option to instead show an interdiff, but doesn't GGG
> already have a way to add some human-written comment

I will work on my cover letters, that's a very fair point.

I do think there is some possibility to handle this via maybe a new
option 'git range-diff --rebase', or directly via GitGitGadget. This would
automatically create a diff with only the files actually changed, which
saves both author's and reviewer's time.

Perhaps this: https://github.com/gitgitgadget/gitgitgadget/pull/2212


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Harald Nordgren <haraldnordgren@gmail.com> writes:

> I do think there is some possibility to handle this via maybe a new
> option 'git range-diff --rebase', or directly via GitGitGadget. This would
> automatically create a diff with only the files actually changed, which
> saves both author's and reviewer's time.

I am not sure.  Have you actually tried to apply two iterations (I
think it was between v11 and v12 but please double check) on the
same base and ran range-diff, and compared the result with what I
complained about?  You added one helper in the new iteration, that
replaces two helpers you added to the old iteration, and the part of
the range-diff that I called "less interesting" noise were the
change to the callers to the original two helpers to make them call
the unified helper, inevitably with different arguments.  I am not
sure a mechanical textual comparison tool can tell them from the
more interesting change that shows that two old helpers did not get
added and instead one new unified helper got added.  I do not expect
this to change if two versions compared were built on the same base.

And that is why I kept saying that the cover letter needs some
comments written by the author to guide readers which parts of the
changes are notable.

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> I am not sure.  Have you actually tried to apply two iterations (I
> think it was between v11 and v12 but please double check) on the
> same base and ran range-diff, and compared the result with what I
> complained about?

Fair enough, it's not great!

> And that is why I kept saying that the cover letter needs some
> comments written by the author to guide readers which parts of the
> changes are notable.

I hear you loud and clear! Next patch will have a better cover letter
if or when it comes!


Harald

[PATCH v13 0/5] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Handling the review comments from Phillip Wood and JCH.

The ones I struggled to fix I commented on on the mailing list instead, wuld
be nice to get some feedback on my proposed fixes 🤗

Harald Nordgren (5):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: rollback lock on early returns in merge_working_tree
  checkout -m: autostash when switching branches

 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 149 +++++++++++------------
 builtin/commit.c                |   3 +-
 builtin/merge.c                 |  15 ++-
 builtin/stash.c                 |  28 +++--
 sequencer.c                     |  73 ++++++++---
 sequencer.h                     |   7 +-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  25 ++++
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 16 files changed, 484 insertions(+), 171 deletions(-)


base-commit: 9e8f4e9c04e3efa494e78b710e0c5f6cc77a0a5e
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v13
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v13
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v12:

 1:  9ab5431b47 ! 1:  43bfdf2136 stash: add --label-ours, --label-theirs, --label-base for apply
     @@ builtin/stash.c
       	N_("git stash branch <branchname> [<stash>]")
       #define BUILTIN_STASH_STORE_USAGE \
      @@ builtin/stash.c: static void unstage_changes_unless_new(struct object_id *orig_tree)
     - 		die(_("could not write index"));
       }
       
     --static int do_apply_stash(const char *prefix, struct stash_info *info,
     + static int do_apply_stash(const char *prefix, struct stash_info *info,
      -			  int index, int quiet)
     -+static int do_apply_stash_with_labels(const char *prefix,
     -+				      struct stash_info *info,
     -+				      int index, int quiet,
     -+				      const char *label_ours, const char *label_theirs,
     -+				      const char *label_base)
     ++			  int index, int quiet,
     ++			  const char *label_ours, const char *label_theirs,
     ++			  const char *label_base)
       {
       	int clean, ret;
       	int has_index = index;
     @@ builtin/stash.c: static int do_apply_stash(const char *prefix, struct stash_info
       
       	if (oideq(&info->b_tree, &c_tree))
       		o.branch1 = "Version stash was based on";
     -@@ builtin/stash.c: restore_untracked:
     - 	return ret;
     - }
     - 
     -+static int do_apply_stash(const char *prefix, struct stash_info *info,
     -+			  int index, int quiet)
     -+{
     -+	return do_apply_stash_with_labels(prefix, info, index, quiet,
     -+					  NULL, NULL, NULL);
     -+}
     -+
     - static int apply_stash(int argc, const char **argv, const char *prefix,
     - 		       struct repository *repo UNUSED)
     - {
     +@@ builtin/stash.c: static int apply_stash(int argc, const char **argv, const char *prefix,
       	int ret = -1;
       	int quiet = 0;
       	int index = use_index;
     @@ builtin/stash.c: static int apply_stash(int argc, const char **argv, const char
       		goto cleanup;
       
      -	ret = do_apply_stash(prefix, &info, index, quiet);
     -+	ret = do_apply_stash_with_labels(prefix, &info, index, quiet,
     -+					 label_ours, label_theirs, label_base);
     ++	ret = do_apply_stash(prefix, &info, index, quiet,
     ++			     label_ours, label_theirs, label_base);
       cleanup:
       	free_stash_info(&info);
       	return ret;
     +@@ builtin/stash.c: static int pop_stash(int argc, const char **argv, const char *prefix,
     + 	if (get_stash_info_assert(&info, argc, argv))
     + 		goto cleanup;
     + 
     +-	if ((ret = do_apply_stash(prefix, &info, index, quiet)))
     ++	if ((ret = do_apply_stash(prefix, &info, index, quiet,
     ++				  NULL, NULL, NULL)))
     + 		printf_ln(_("The stash entry is kept in case "
     + 			    "you need it again."));
     + 	else
     +@@ builtin/stash.c: static int branch_stash(int argc, const char **argv, const char *prefix,
     + 	strvec_push(&cp.args, oid_to_hex(&info.b_commit));
     + 	ret = run_command(&cp);
     + 	if (!ret)
     +-		ret = do_apply_stash(prefix, &info, 1, 0);
     ++		ret = do_apply_stash(prefix, &info, 1, 0,
     ++				     NULL, NULL, NULL);
     + 	if (!ret && info.is_stash_ref)
     + 		ret = do_drop_stash(&info, 0);
     + 
      
       ## t/t3903-stash.sh ##
      @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit conflicts' '
     @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
       '
       
      +test_expect_success 'apply with custom conflict labels' '
     -+	git init conflict_labels &&
     -+	(
     -+		cd conflict_labels &&
     -+		test_commit base file &&
     -+		echo stashed >file &&
     -+		git stash push -m "stashed" &&
     -+		test_commit upstream file &&
     -+		test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
     -+		test_grep "^<<<<<<< UP" file &&
     -+		test_grep "^||||||| Stash base" file &&
     -+		test_grep "^>>>>>>> STASH" file
     -+	)
     ++	test_when_finished "git reset --hard && git stash drop" &&
     ++	git reset --hard &&
     ++	test_commit label-base conflict-file base-content &&
     ++	echo stashed >conflict-file &&
     ++	git stash push -m "stashed" &&
     ++	test_commit label-upstream conflict-file upstream-content &&
     ++	test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
     ++	test_grep "^<<<<<<< UP" conflict-file &&
     ++	test_grep "^||||||| Stash base" conflict-file &&
     ++	test_grep "^>>>>>>> STASH" conflict-file
      +'
      +
      +test_expect_success 'apply with empty conflict labels' '
     -+	git init empty_labels &&
     -+	(
     -+		cd empty_labels &&
     -+		test_commit base file &&
     -+		echo stashed >file &&
     -+		git stash push -m "stashed" &&
     -+		test_commit upstream file &&
     -+		test_must_fail git stash apply --label-ours= --label-theirs= &&
     -+		test_grep "^<<<<<<<$" file &&
     -+		test_grep "^>>>>>>>$" file
     -+	)
     ++	test_when_finished "git reset --hard && git stash drop" &&
     ++	git reset --hard &&
     ++	test_commit empty-label-base conflict-file base-content &&
     ++	echo stashed >conflict-file &&
     ++	git stash push -m "stashed" &&
     ++	test_commit empty-label-upstream conflict-file upstream-content &&
     ++	test_must_fail git stash apply --label-ours= --label-theirs= &&
     ++	test_grep "^<<<<<<<$" conflict-file &&
     ++	test_grep "^>>>>>>>$" conflict-file
      +'
      +
       test_expect_success 'stash create reports a locked index' '
 2:  e11a622bdf ! 2:  7f3c32f5e9 sequencer: allow create_autostash to run silently
     @@ Commit message
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     + ## builtin/merge.c ##
     +@@ builtin/merge.c: int cmd_merge(int argc,
     + 		}
     + 
     + 		if (autostash)
     +-			create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
     ++			create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
     ++					     NULL, false);
     + 		if (checkout_fast_forward(the_repository,
     + 					  &head_commit->object.oid,
     + 					  &commit->object.oid,
     +@@ builtin/merge.c: int cmd_merge(int argc,
     + 		die_ff_impossible();
     + 
     + 	if (autostash)
     +-		create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
     ++		create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
     ++				     NULL, false);
     + 
     + 	/* We are going to make a new commit. */
     + 	git_committer_info(IDENT_STRICT);
     +
       ## sequencer.c ##
      @@ sequencer.c: static enum todo_command peek_command(struct todo_list *todo_list, int offset)
       
     @@ sequencer.c: static void create_autostash_internal(struct repository *r,
      +	create_autostash_internal(r, path, NULL, NULL, false);
       }
       
     - void create_autostash_ref(struct repository *r, const char *refname)
     +-void create_autostash_ref(struct repository *r, const char *refname)
     ++void create_autostash_ref(struct repository *r, const char *refname,
     ++			  const char *message, bool silent)
       {
      -	create_autostash_internal(r, NULL, refname);
     -+	create_autostash_internal(r, NULL, refname, NULL, false);
     -+}
     -+
     -+void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
     -+				 const char *message)
     -+{
     -+	create_autostash_internal(r, NULL, refname, message, true);
     ++	create_autostash_internal(r, NULL, refname, message, silent);
       }
       
       static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
      
       ## sequencer.h ##
      @@ sequencer.h: void commit_post_rewrite(struct repository *r,
     + 			 const struct object_id *new_head);
       
       void create_autostash(struct repository *r, const char *path);
     - void create_autostash_ref(struct repository *r, const char *refname);
     -+void create_autostash_ref_with_msg_silent(struct repository *r, const char *refname,
     -+				 const char *message);
     +-void create_autostash_ref(struct repository *r, const char *refname);
     ++void create_autostash_ref(struct repository *r, const char *refname,
     ++			  const char *message, bool silent);
       int save_autostash(const char *path);
       int save_autostash_ref(struct repository *r, const char *refname);
       int apply_autostash(const char *path);
 3:  4593745e90 ! 3:  b279d1dac8 sequencer: teach autostash apply to take optional conflict marker labels
     @@ Metadata
       ## Commit message ##
          sequencer: teach autostash apply to take optional conflict marker labels
      
     -    Add label_ours, label_theirs, and label_base parameters to the autostash
     -    apply machinery so callers can pass custom conflict marker labels
     -    through to "git stash apply --label-ours/--label-theirs/--label-base".
     -    Introduce apply_autostash_ref_with_labels() for callers that want
     -    to pass labels.
     +    Add label_ours, label_theirs, label_base, and stash_msg parameters to
     +    apply_autostash_ref() and the autostash apply machinery so callers can
     +    pass custom conflict marker labels through to
     +    "git stash apply --label-ours/--label-theirs/--label-base", as well as
     +    a custom stash message for "git stash store -m".
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     + ## builtin/commit.c ##
     +@@ builtin/commit.c: int cmd_commit(int argc,
     + 				     &oid, flags);
     + 	}
     + 
     +-	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
     ++	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
     ++			    NULL, NULL, NULL, NULL);
     + 
     + cleanup:
     + 	free_commit_extra_headers(extra);
     +
     + ## builtin/merge.c ##
     +@@ builtin/merge.c: static void finish(struct commit *head_commit,
     + 	run_hooks_l(the_repository, "post-merge", squash ? "1" : "0", NULL);
     + 
     + 	if (new_head)
     +-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
     ++		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
     ++				    NULL, NULL, NULL, NULL);
     + 	strbuf_release(&reflog_message);
     + }
     + 
     +@@ builtin/merge.c: int cmd_merge(int argc,
     + 					  &head_commit->object.oid,
     + 					  &commit->object.oid,
     + 					  overwrite_ignore)) {
     +-			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
     ++			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
     ++					    NULL, NULL, NULL, NULL);
     + 			ret = 1;
     + 			goto done;
     + 		}
     +@@ builtin/merge.c: int cmd_merge(int argc,
     + 		else
     + 			fprintf(stderr, _("Merge with strategy %s failed.\n"),
     + 				use_strategies[0]->name);
     +-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
     ++		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
     ++				    NULL, NULL, NULL, NULL);
     + 		ret = 2;
     + 		goto done;
     + 	} else if (best_strategy == wt_strategy)
     +
       ## sequencer.c ##
     -@@ sequencer.c: void create_autostash_ref_with_msg_silent(struct repository *r, const char *refn
     - 	create_autostash_internal(r, NULL, refname, message, true);
     +@@ sequencer.c: void create_autostash_ref(struct repository *r, const char *refname,
     + 	create_autostash_internal(r, NULL, refname, message, silent);
       }
       
      -static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
     @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
      +					NULL, NULL, NULL, NULL);
       }
       
     - int apply_autostash_ref(struct repository *r, const char *refname)
     +-int apply_autostash_ref(struct repository *r, const char *refname)
     ++int apply_autostash_ref(struct repository *r, const char *refname,
     ++			const char *label_ours, const char *label_theirs,
     ++			const char *label_base, const char *stash_msg)
       {
      -	return apply_save_autostash_ref(r, refname, 1);
      +	return apply_save_autostash_ref(r, refname, 1,
     -+					NULL, NULL, NULL, NULL);
     -+}
     -+
     -+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     -+				    const char *label_ours, const char *label_theirs,
     -+				    const char *label_base,
     -+				    const char *stash_msg)
     -+{
     -+	return apply_save_autostash_ref(r, refname, 1,
      +					label_ours, label_theirs, label_base,
      +					stash_msg);
       }
     @@ sequencer.c: static int apply_save_autostash_ref(struct repository *r, const cha
       static int checkout_onto(struct repository *r, struct replay_opts *opts,
      
       ## sequencer.h ##
     -@@ sequencer.h: int save_autostash_ref(struct repository *r, const char *refname);
     +@@ sequencer.h: int save_autostash(const char *path);
     + int save_autostash_ref(struct repository *r, const char *refname);
       int apply_autostash(const char *path);
       int apply_autostash_oid(const char *stash_oid);
     - int apply_autostash_ref(struct repository *r, const char *refname);
     -+int apply_autostash_ref_with_labels(struct repository *r, const char *refname,
     -+				    const char *label_ours, const char *label_theirs,
     -+				    const char *label_base,
     -+				    const char *stash_msg);
     +-int apply_autostash_ref(struct repository *r, const char *refname);
     ++int apply_autostash_ref(struct repository *r, const char *refname,
     ++			const char *label_ours, const char *label_theirs,
     ++			const char *label_base, const char *stash_msg);
       
       #define SUMMARY_INITIAL_COMMIT   (1 << 0)
       #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
 -:  ---------- > 4:  04869314ec checkout: rollback lock on early returns in merge_working_tree
 4:  911e520431 ! 5:  4b3c6025ac checkout: -m (--merge) uses autostash when switching branches
     @@ Metadata
      Author: Harald Nordgren <haraldnordgren@gmail.com>
      
       ## Commit message ##
     -    checkout: -m (--merge) uses autostash when switching branches
     +    checkout -m: autostash when switching branches
      
     -    When switching branches with "git checkout -m", local modifications
     -    can block the switch.  Teach the -m flow to create a temporary stash
     -    before switching and reapply it after.  On success, only "Applied
     -    autostash." is shown.  If reapplying causes conflicts, the stash is
     -    kept and the user is told they can resolve and run "git stash drop",
     -    or run "git reset --hard" and later "git stash pop" to recover their
     -    changes.
     +    When switching branches with "git checkout -m", the attempted merge
     +    of local modifications may cause conflicts with the changes made on
     +    the other branch, which the user may not want to (or may not be able
     +    to) resolve right now.  Because there is no easy way to recover from
     +    this situation, we discouraged users from using "checkout -m" unless
     +    they are certain their changes are trivial and within their ability
     +    to resolve conflicts.
     +
     +    Teach the -m flow to create a temporary stash before switching and
     +    reapply it after.  On success, the stash is silently applied and
     +    the list of locally modified paths is shown, same as a successful
     +    "git checkout" without "-m".
     +
     +    If reapplying causes conflicts, the stash is kept and the user is
     +    told they can resolve and run "git stash drop", or run "git reset
     +    --hard" and later "git stash pop" to recover their changes.
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     @@ builtin/checkout.c
       #include "setup.h"
       #include "submodule.h"
       #include "symlinks.h"
     -@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     - 	struct tree *new_tree;
     - 
     - 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
     --	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
     -+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
     -+		rollback_lock_file(&lock_file);
     - 		return error(_("index file corrupt"));
     -+	}
     - 
     - 	resolve_undo_clear_index(the_repository->index);
     - 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
     -@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     - 	} else {
     - 		new_tree = repo_get_commit_tree(the_repository,
     - 						new_branch_info->commit);
     --		if (!new_tree)
     -+		if (!new_tree) {
     -+			rollback_lock_file(&lock_file);
     - 			return error(_("unable to read tree (%s)"),
     - 				     oid_to_hex(&new_branch_info->commit->object.oid));
     -+		}
     - 	}
     - 	if (opts->discard_changes) {
     - 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
     --		if (ret)
     -+		if (ret) {
     -+			rollback_lock_file(&lock_file);
     - 			return ret;
     -+		}
     - 	} else {
     - 		struct tree_desc trees[2];
     - 		struct tree *tree;
     -@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     - 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
     - 
     - 		if (unmerged_index(the_repository->index)) {
     -+			rollback_lock_file(&lock_file);
     - 			error(_("you need to resolve your current index first"));
     - 			return 1;
     - 		}
      @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
       		ret = unpack_trees(2, trees, &topts);
       		clear_unpack_trees_porcelain(&topts);
     @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
      -			struct strbuf sb = STRBUF_INIT;
      -			struct strbuf old_commit_shortname = STRBUF_INIT;
      -
     --			if (!opts->merge)
     +-			if (!opts->merge) {
     +-				rollback_lock_file(&lock_file);
      -				return 1;
     +-			}
      -
      -			/*
      -			 * Without old_branch_info->commit, the below is the same as
      -			 * the two-tree unpack we already tried and failed.
      -			 */
     --			if (!old_branch_info->commit)
     +-			if (!old_branch_info->commit) {
     +-				rollback_lock_file(&lock_file);
      -				return 1;
     +-			}
      -			old_tree = repo_get_commit_tree(the_repository,
      -							old_branch_info->commit);
      -
     @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
      -			ret = reset_tree(new_tree,
      -					 opts, 1,
      -					 writeout_error, new_branch_info);
     --			if (ret)
     +-			if (ret) {
     +-				rollback_lock_file(&lock_file);
      -				return ret;
     +-			}
      -			o.ancestor = old_branch_info->name;
      -			if (!old_branch_info->name) {
      -				strbuf_add_unique_abbrev(&old_commit_shortname,
     @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
      -					 writeout_error, new_branch_info);
      -			strbuf_release(&o.obuf);
      -			strbuf_release(&old_commit_shortname);
     --			if (ret)
     +-			if (ret) {
     +-				rollback_lock_file(&lock_file);
      -				return ret;
     +-			}
      +			rollback_lock_file(&lock_file);
     -+			return 1;
     ++			return ret;
       		}
       	}
       
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +
       	if (do_merge) {
       		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
     -+		if (ret && opts->merge) {
     ++		if (ret == -1 && opts->merge) {
      +			strbuf_addf(&autostash_msg,
      +				    "autostash while switching to '%s'",
      +				    new_branch_info->name);
     -+			create_autostash_ref_with_msg_silent(the_repository,
     -+						   "CHECKOUT_AUTOSTASH_HEAD",
     -+						   autostash_msg.buf);
     ++			create_autostash_ref(the_repository,
     ++					     "CHECKOUT_AUTOSTASH_HEAD",
     ++					     autostash_msg.buf, true);
      +			created_autostash = 1;
      +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		}
       		if (ret) {
     -+			apply_autostash_ref_with_labels(the_repository,
     -+						       "CHECKOUT_AUTOSTASH_HEAD",
     -+						       new_branch_info->name,
     -+						       "local",
     -+						       stash_label_base,
     -+						       autostash_msg.len ? autostash_msg.buf : NULL);
     ++			if (created_autostash)
     ++				apply_autostash_ref(the_repository,
     ++						    "CHECKOUT_AUTOSTASH_HEAD",
     ++						    new_branch_info->name,
     ++						    "local",
     ++						    stash_label_base,
     ++						    autostash_msg.buf);
       			branch_info_release(&old_branch_info);
     +-			return ret;
      +			strbuf_release(&old_commit_shortname);
      +			strbuf_release(&autostash_msg);
     - 			return ret;
     ++			return ret < 0 ? 1 : ret;
       		}
       	}
     + 
      @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       
       	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +		git_config_push_parameter(cfg.buf);
      +		strbuf_release(&cfg);
      +	}
     -+	apply_autostash_ref_with_labels(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
     -+				       new_branch_info->name, "local",
     -+				       stash_label_base,
     -+				       autostash_msg.len ? autostash_msg.buf : NULL);
     ++	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
     ++			    new_branch_info->name, "local",
     ++			    stash_label_base,
     ++			    autostash_msg.buf);
      +
      +	discard_index(the_repository->index);
      +	if (repo_read_index(the_repository) < 0)
      +		die(_("index file corrupt"));
      +
     -+	if (created_autostash && !opts->discard_changes && !opts->quiet &&
     -+	    new_branch_info->commit)
     ++	if (created_autostash && !opts->quiet && new_branch_info->commit)
      +		show_local_changes(&new_branch_info->commit->object,
      +				   &opts->diff_options);
      +

-- 
gitgitgadget

[PATCH v13 1/5] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 28 ++++++++++++++++++++--------
 t/t3903-stash.sh             | 25 +++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 58 insertions(+), 12 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..32dbc97b47 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -591,7 +591,9 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 }
 
 static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+			  int index, int quiet,
+			  const char *label_ours, const char *label_theirs,
+			  const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +645,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -723,11 +725,18 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +746,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash(prefix, &info, index, quiet,
+			     label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
@@ -836,7 +846,8 @@ static int pop_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info_assert(&info, argc, argv))
 		goto cleanup;
 
-	if ((ret = do_apply_stash(prefix, &info, index, quiet)))
+	if ((ret = do_apply_stash(prefix, &info, index, quiet,
+				  NULL, NULL, NULL)))
 		printf_ln(_("The stash entry is kept in case "
 			    "you need it again."));
 	else
@@ -877,7 +888,8 @@ static int branch_stash(int argc, const char **argv, const char *prefix,
 	strvec_push(&cp.args, oid_to_hex(&info.b_commit));
 	ret = run_command(&cp);
 	if (!ret)
-		ret = do_apply_stash(prefix, &info, 1, 0);
+		ret = do_apply_stash(prefix, &info, 1, 0,
+				     NULL, NULL, NULL);
 	if (!ret && info.is_stash_ref)
 		ret = do_drop_stash(&info, 0);
 
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..340854bc0a 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1666,6 +1666,31 @@ test_expect_success 'restore untracked files even when we hit conflicts' '
 	)
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	test_when_finished "git reset --hard && git stash drop" &&
+	git reset --hard &&
+	test_commit label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit label-upstream conflict-file upstream-content &&
+	test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+	test_grep "^<<<<<<< UP" conflict-file &&
+	test_grep "^||||||| Stash base" conflict-file &&
+	test_grep "^>>>>>>> STASH" conflict-file
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	test_when_finished "git reset --hard && git stash drop" &&
+	git reset --hard &&
+	test_commit empty-label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit empty-label-upstream conflict-file upstream-content &&
+	test_must_fail git stash apply --label-ours= --label-theirs= &&
+	test_grep "^<<<<<<<$" conflict-file &&
+	test_grep "^>>>>>>>$" conflict-file
+'
+
 test_expect_success 'stash create reports a locked index' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

[PATCH v13 2/5] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/merge.c |  6 ++++--
 sequencer.c     | 17 +++++++++++------
 sequencer.h     |  3 ++-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index 2cbce56f8d..3ebe190ef1 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1672,7 +1672,8 @@ int cmd_merge(int argc,
 		}
 
 		if (autostash)
-			create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					     NULL, false);
 		if (checkout_fast_forward(the_repository,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
@@ -1764,7 +1765,8 @@ int cmd_merge(int argc,
 		die_ff_impossible();
 
 	if (autostash)
-		create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				     NULL, false);
 
 	/* We are going to make a new commit. */
 	git_committer_info(IDENT_STRICT);
diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..ff5258f481 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,9 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      const char *message,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4679,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
 		struct object_id oid;
 
 		strvec_pushl(&stash.args,
-			     "stash", "create", "autostash", NULL);
+			     "stash", "create",
+			     message ? message : "autostash", NULL);
 		stash.git_cmd = 1;
 		stash.no_stdin = 1;
 		strbuf_reset(&buf);
@@ -4702,7 +4705,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4718,13 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, NULL, false);
 }
 
-void create_autostash_ref(struct repository *r, const char *refname)
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..02d2d9db06 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -229,7 +229,8 @@ void commit_post_rewrite(struct repository *r,
 			 const struct object_id *new_head);
 
 void create_autostash(struct repository *r, const char *path);
-void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v13 3/5] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, label_base, and stash_msg parameters to
apply_autostash_ref() and the autostash apply machinery so callers can
pass custom conflict marker labels through to
"git stash apply --label-ours/--label-theirs/--label-base", as well as
a custom stash message for "git stash store -m".

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/commit.c |  3 ++-
 builtin/merge.c  |  9 ++++++---
 sequencer.c      | 38 +++++++++++++++++++++++++++++---------
 sequencer.h      |  4 +++-
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index a3e52ac9ca..28f6174503 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1979,7 +1979,8 @@ int cmd_commit(int argc,
 				     &oid, flags);
 	}
 
-	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+			    NULL, NULL, NULL, NULL);
 
 cleanup:
 	free_commit_extra_headers(extra);
diff --git a/builtin/merge.c b/builtin/merge.c
index 3ebe190ef1..aacf8c524e 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -537,7 +537,8 @@ static void finish(struct commit *head_commit,
 	run_hooks_l(the_repository, "post-merge", squash ? "1" : "0", NULL);
 
 	if (new_head)
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 	strbuf_release(&reflog_message);
 }
 
@@ -1678,7 +1679,8 @@ int cmd_merge(int argc,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
 					  overwrite_ignore)) {
-			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					    NULL, NULL, NULL, NULL);
 			ret = 1;
 			goto done;
 		}
@@ -1851,7 +1853,8 @@ int cmd_merge(int argc,
 		else
 			fprintf(stderr, _("Merge with strategy %s failed.\n"),
 				use_strategies[0]->name);
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 		ret = 2;
 		goto done;
 	} else if (best_strategy == wt_strategy)
diff --git a/sequencer.c b/sequencer.c
index ff5258f481..7c0376d9e4 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4727,7 +4727,10 @@ void create_autostash_ref(struct repository *r, const char *refname,
 	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4738,6 +4741,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4751,7 +4760,7 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		strvec_push(&store.args, "stash");
 		strvec_push(&store.args, "store");
 		strvec_push(&store.args, "-m");
-		strvec_push(&store.args, "autostash");
+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
 		strvec_push(&store.args, "-q");
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
@@ -4782,7 +4791,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4801,11 +4811,14 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4821,7 +4834,9 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base,
+				       stash_msg);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4831,12 +4846,17 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0,
+					NULL, NULL, NULL, NULL);
 }
 
-int apply_autostash_ref(struct repository *r, const char *refname)
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base,
+					stash_msg);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 02d2d9db06..3164bd437d 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -235,7 +235,9 @@ int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
-int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v13 4/5] checkout: rollback lock on early returns in merge_working_tree

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

merge_working_tree() acquires the index lock via
repo_hold_locked_index() but several early return paths exit
without calling rollback_lock_file(), leaving the lock held.
While this is currently harmless because the process exits soon
after, it becomes a problem if the function is ever called more
than once in the same process.

Add rollback_lock_file() calls to all early return paths.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/checkout.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..c80c62b37b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -857,15 +864,19 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			struct strbuf sb = STRBUF_INIT;
 			struct strbuf old_commit_shortname = STRBUF_INIT;
 
-			if (!opts->merge)
+			if (!opts->merge) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 
 			/*
 			 * Without old_branch_info->commit, the below is the same as
 			 * the two-tree unpack we already tried and failed.
 			 */
-			if (!old_branch_info->commit)
+			if (!old_branch_info->commit) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 			old_tree = repo_get_commit_tree(the_repository,
 							old_branch_info->commit);
 
@@ -897,8 +908,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			ret = reset_tree(new_tree,
 					 opts, 1,
 					 writeout_error, new_branch_info);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 			o.ancestor = old_branch_info->name;
 			if (!old_branch_info->name) {
 				strbuf_add_unique_abbrev(&old_commit_shortname,
@@ -920,8 +933,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 					 writeout_error, new_branch_info);
 			strbuf_release(&o.obuf);
 			strbuf_release(&old_commit_shortname);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 		}
 	}
 
-- 
gitgitgadget

[PATCH v13 5/5] checkout -m: autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", the attempted merge
of local modifications may cause conflicts with the changes made on
the other branch, which the user may not want to (or may not be able
to) resolve right now.  Because there is no easy way to recover from
this situation, we discouraged users from using "checkout -m" unless
they are certain their changes are trivial and within their ability
to resolve conflicts.

Teach the -m flow to create a temporary stash before switching and
reapply it after.  On success, the stash is silently applied and
the list of locally modified paths is shown, same as a successful
"git checkout" without "-m".

If reapplying causes conflicts, the stash is kept and the user is
told they can resolve and run "git stash drop", or run "git reset
--hard" and later "git stash pop" to recover their changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 144 +++++++++-------------
 sequencer.c                     |  18 ++-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 9 files changed, 359 insertions(+), 141 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index c80c62b37b..55c4db04c6 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -853,90 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
+			rollback_lock_file(&lock_file);
+			return ret;
 		}
 	}
 
@@ -1181,6 +1099,10 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	struct strbuf autostash_msg = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1218,11 +1140,39 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_base = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret == -1 && opts->merge) {
+			strbuf_addf(&autostash_msg,
+				    "autostash while switching to '%s'",
+				    new_branch_info->name);
+			create_autostash_ref(the_repository,
+					     "CHECKOUT_AUTOSTASH_HEAD",
+					     autostash_msg.buf, true);
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			if (created_autostash)
+				apply_autostash_ref(the_repository,
+						    "CHECKOUT_AUTOSTASH_HEAD",
+						    new_branch_info->name,
+						    "local",
+						    stash_label_base,
+						    autostash_msg.buf);
 			branch_info_release(&old_branch_info);
-			return ret;
+			strbuf_release(&old_commit_shortname);
+			strbuf_release(&autostash_msg);
+			return ret < 0 ? 1 : ret;
 		}
 	}
 
@@ -1231,8 +1181,30 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
+			    new_branch_info->name, "local",
+			    stash_label_base,
+			    autostash_msg.buf);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->quiet && new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
+	strbuf_release(&autostash_msg);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index 7c0376d9e4..480e8e6c0b 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4765,15 +4765,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..c474c6759f 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,214 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git stash list >stash-before &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m autostash message includes target branch' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	git stash list >stash-list &&
+	test_grep "autostash while switching to .side." stash-list &&
+	git stash drop &&
+	git checkout -f main &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git stash list >stash-before &&
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

[PATCH v14 0/5] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

Simplifying the tests in t/t3903-stash.sh according to Phillip Wood's
comment. I believe everything sound be fixed now or responded to.

Also rebasing against upstream.

Harald Nordgren (5):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: rollback lock on early returns in merge_working_tree
  checkout -m: autostash when switching branches

 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-stash.adoc    |  11 +-
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 149 +++++++++++------------
 builtin/commit.c                |   3 +-
 builtin/merge.c                 |  15 ++-
 builtin/stash.c                 |  28 +++--
 sequencer.c                     |  73 ++++++++---
 sequencer.h                     |   7 +-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t3903-stash.sh                |  24 ++++
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 16 files changed, 483 insertions(+), 171 deletions(-)


base-commit: 9f223ef1c026d91c7ac68cc0211bde255dda6199
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v14
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v14
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v13:

 1:  43bfdf2136 ! 1:  e18c25599a stash: add --label-ours, --label-theirs, --label-base for apply
     @@ builtin/stash.c: static int branch_stash(int argc, const char **argv, const char
       
      
       ## t/t3903-stash.sh ##
     -@@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit conflicts' '
     - 	)
     +@@ t/t3903-stash.sh: setup_stash() {
     + 	git add other-file &&
     + 	test_tick &&
     + 	git commit -m initial &&
     ++	git tag initial &&
     + 	echo 2 >file &&
     + 	git add file &&
     + 	echo 3 >file &&
     +@@ t/t3903-stash.sh: test_expect_success 'stash.index=false overridden by --index' '
     + 	test_cmp expect file
       '
       
      +test_expect_success 'apply with custom conflict labels' '
     -+	test_when_finished "git reset --hard && git stash drop" &&
     -+	git reset --hard &&
     ++	git reset --hard initial &&
      +	test_commit label-base conflict-file base-content &&
      +	echo stashed >conflict-file &&
      +	git stash push -m "stashed" &&
     @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
      +'
      +
      +test_expect_success 'apply with empty conflict labels' '
     -+	test_when_finished "git reset --hard && git stash drop" &&
     -+	git reset --hard &&
     ++	git reset --hard initial &&
      +	test_commit empty-label-base conflict-file base-content &&
      +	echo stashed >conflict-file &&
      +	git stash push -m "stashed" &&
     @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
      +	test_grep "^>>>>>>>$" conflict-file
      +'
      +
     - test_expect_success 'stash create reports a locked index' '
     - 	test_when_finished "rm -rf repo" &&
     - 	git init repo &&
     + test_done
      
       ## xdiff/xmerge.c ##
      @@ xdiff/xmerge.c: static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 2:  7f3c32f5e9 = 2:  ce29b10264 sequencer: allow create_autostash to run silently
 3:  b279d1dac8 = 3:  73051d1762 sequencer: teach autostash apply to take optional conflict marker labels
 4:  04869314ec = 4:  191058d8e3 checkout: rollback lock on early returns in merge_working_tree
 5:  4b3c6025ac = 5:  86f33df1eb checkout -m: autostash when switching branches

-- 
gitgitgadget

[PATCH v14 1/5] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 28 ++++++++++++++++++++--------
 t/t3903-stash.sh             | 24 ++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 57 insertions(+), 12 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..32dbc97b47 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -591,7 +591,9 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 }
 
 static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+			  int index, int quiet,
+			  const char *label_ours, const char *label_theirs,
+			  const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +645,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -723,11 +725,18 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +746,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash(prefix, &info, index, quiet,
+			     label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
@@ -836,7 +846,8 @@ static int pop_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info_assert(&info, argc, argv))
 		goto cleanup;
 
-	if ((ret = do_apply_stash(prefix, &info, index, quiet)))
+	if ((ret = do_apply_stash(prefix, &info, index, quiet,
+				  NULL, NULL, NULL)))
 		printf_ln(_("The stash entry is kept in case "
 			    "you need it again."));
 	else
@@ -877,7 +888,8 @@ static int branch_stash(int argc, const char **argv, const char *prefix,
 	strvec_push(&cp.args, oid_to_hex(&info.b_commit));
 	ret = run_command(&cp);
 	if (!ret)
-		ret = do_apply_stash(prefix, &info, 1, 0);
+		ret = do_apply_stash(prefix, &info, 1, 0,
+				     NULL, NULL, NULL);
 	if (!ret && info.is_stash_ref)
 		ret = do_drop_stash(&info, 0);
 
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..bdaad22e1f 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -56,6 +56,7 @@ setup_stash() {
 	git add other-file &&
 	test_tick &&
 	git commit -m initial &&
+	git tag initial &&
 	echo 2 >file &&
 	git add file &&
 	echo 3 >file &&
@@ -1790,4 +1791,27 @@ test_expect_success 'stash.index=false overridden by --index' '
 	test_cmp expect file
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git reset --hard initial &&
+	test_commit label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit label-upstream conflict-file upstream-content &&
+	test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+	test_grep "^<<<<<<< UP" conflict-file &&
+	test_grep "^||||||| Stash base" conflict-file &&
+	test_grep "^>>>>>>> STASH" conflict-file
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git reset --hard initial &&
+	test_commit empty-label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit empty-label-upstream conflict-file upstream-content &&
+	test_must_fail git stash apply --label-ours= --label-theirs= &&
+	test_grep "^<<<<<<<$" conflict-file &&
+	test_grep "^>>>>>>>$" conflict-file
+'
+
 test_done
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

[PATCH v14 2/5] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/merge.c |  6 ++++--
 sequencer.c     | 17 +++++++++++------
 sequencer.h     |  3 ++-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index 2cbce56f8d..3ebe190ef1 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1672,7 +1672,8 @@ int cmd_merge(int argc,
 		}
 
 		if (autostash)
-			create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					     NULL, false);
 		if (checkout_fast_forward(the_repository,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
@@ -1764,7 +1765,8 @@ int cmd_merge(int argc,
 		die_ff_impossible();
 
 	if (autostash)
-		create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				     NULL, false);
 
 	/* We are going to make a new commit. */
 	git_committer_info(IDENT_STRICT);
diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..ff5258f481 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,9 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      const char *message,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4679,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
 		struct object_id oid;
 
 		strvec_pushl(&stash.args,
-			     "stash", "create", "autostash", NULL);
+			     "stash", "create",
+			     message ? message : "autostash", NULL);
 		stash.git_cmd = 1;
 		stash.no_stdin = 1;
 		strbuf_reset(&buf);
@@ -4702,7 +4705,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4718,13 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, NULL, false);
 }
 
-void create_autostash_ref(struct repository *r, const char *refname)
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..02d2d9db06 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -229,7 +229,8 @@ void commit_post_rewrite(struct repository *r,
 			 const struct object_id *new_head);
 
 void create_autostash(struct repository *r, const char *path);
-void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v14 3/5] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, label_base, and stash_msg parameters to
apply_autostash_ref() and the autostash apply machinery so callers can
pass custom conflict marker labels through to
"git stash apply --label-ours/--label-theirs/--label-base", as well as
a custom stash message for "git stash store -m".

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/commit.c |  3 ++-
 builtin/merge.c  |  9 ++++++---
 sequencer.c      | 38 +++++++++++++++++++++++++++++---------
 sequencer.h      |  4 +++-
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index a3e52ac9ca..28f6174503 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1979,7 +1979,8 @@ int cmd_commit(int argc,
 				     &oid, flags);
 	}
 
-	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+			    NULL, NULL, NULL, NULL);
 
 cleanup:
 	free_commit_extra_headers(extra);
diff --git a/builtin/merge.c b/builtin/merge.c
index 3ebe190ef1..aacf8c524e 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -537,7 +537,8 @@ static void finish(struct commit *head_commit,
 	run_hooks_l(the_repository, "post-merge", squash ? "1" : "0", NULL);
 
 	if (new_head)
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 	strbuf_release(&reflog_message);
 }
 
@@ -1678,7 +1679,8 @@ int cmd_merge(int argc,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
 					  overwrite_ignore)) {
-			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					    NULL, NULL, NULL, NULL);
 			ret = 1;
 			goto done;
 		}
@@ -1851,7 +1853,8 @@ int cmd_merge(int argc,
 		else
 			fprintf(stderr, _("Merge with strategy %s failed.\n"),
 				use_strategies[0]->name);
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 		ret = 2;
 		goto done;
 	} else if (best_strategy == wt_strategy)
diff --git a/sequencer.c b/sequencer.c
index ff5258f481..7c0376d9e4 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4727,7 +4727,10 @@ void create_autostash_ref(struct repository *r, const char *refname,
 	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4738,6 +4741,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4751,7 +4760,7 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		strvec_push(&store.args, "stash");
 		strvec_push(&store.args, "store");
 		strvec_push(&store.args, "-m");
-		strvec_push(&store.args, "autostash");
+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
 		strvec_push(&store.args, "-q");
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
@@ -4782,7 +4791,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4801,11 +4811,14 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4821,7 +4834,9 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base,
+				       stash_msg);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4831,12 +4846,17 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0,
+					NULL, NULL, NULL, NULL);
 }
 
-int apply_autostash_ref(struct repository *r, const char *refname)
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base,
+					stash_msg);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 02d2d9db06..3164bd437d 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -235,7 +235,9 @@ int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
-int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v14 4/5] checkout: rollback lock on early returns in merge_working_tree

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

merge_working_tree() acquires the index lock via
repo_hold_locked_index() but several early return paths exit
without calling rollback_lock_file(), leaving the lock held.
While this is currently harmless because the process exits soon
after, it becomes a problem if the function is ever called more
than once in the same process.

Add rollback_lock_file() calls to all early return paths.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/checkout.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..c80c62b37b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -857,15 +864,19 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			struct strbuf sb = STRBUF_INIT;
 			struct strbuf old_commit_shortname = STRBUF_INIT;
 
-			if (!opts->merge)
+			if (!opts->merge) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 
 			/*
 			 * Without old_branch_info->commit, the below is the same as
 			 * the two-tree unpack we already tried and failed.
 			 */
-			if (!old_branch_info->commit)
+			if (!old_branch_info->commit) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 			old_tree = repo_get_commit_tree(the_repository,
 							old_branch_info->commit);
 
@@ -897,8 +908,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			ret = reset_tree(new_tree,
 					 opts, 1,
 					 writeout_error, new_branch_info);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 			o.ancestor = old_branch_info->name;
 			if (!old_branch_info->name) {
 				strbuf_add_unique_abbrev(&old_commit_shortname,
@@ -920,8 +933,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 					 writeout_error, new_branch_info);
 			strbuf_release(&o.obuf);
 			strbuf_release(&old_commit_shortname);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 		}
 	}
 
-- 
gitgitgadget

[PATCH v14 5/5] checkout -m: autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", the attempted merge
of local modifications may cause conflicts with the changes made on
the other branch, which the user may not want to (or may not be able
to) resolve right now.  Because there is no easy way to recover from
this situation, we discouraged users from using "checkout -m" unless
they are certain their changes are trivial and within their ability
to resolve conflicts.

Teach the -m flow to create a temporary stash before switching and
reapply it after.  On success, the stash is silently applied and
the list of locally modified paths is shown, same as a successful
"git checkout" without "-m".

If reapplying causes conflicts, the stash is kept and the user is
told they can resolve and run "git stash drop", or run "git reset
--hard" and later "git stash pop" to recover their changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 ++++-----
 Documentation/git-switch.adoc   |  33 ++---
 builtin/checkout.c              | 144 +++++++++-------------
 sequencer.c                     |  18 ++-
 t/t3420-rebase-autostash.sh     |  24 +++-
 t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
 t/t7600-merge.sh                |   2 +-
 xdiff-interface.c               |  12 ++
 xdiff-interface.h               |   1 +
 9 files changed, 359 insertions(+), 141 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index c80c62b37b..55c4db04c6 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -853,90 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
+			rollback_lock_file(&lock_file);
+			return ret;
 		}
 	}
 
@@ -1181,6 +1099,10 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	struct strbuf autostash_msg = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1218,11 +1140,39 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name)
+		stash_label_base = old_branch_info.name;
+	else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		if (ret == -1 && opts->merge) {
+			strbuf_addf(&autostash_msg,
+				    "autostash while switching to '%s'",
+				    new_branch_info->name);
+			create_autostash_ref(the_repository,
+					     "CHECKOUT_AUTOSTASH_HEAD",
+					     autostash_msg.buf, true);
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		}
 		if (ret) {
+			if (created_autostash)
+				apply_autostash_ref(the_repository,
+						    "CHECKOUT_AUTOSTASH_HEAD",
+						    new_branch_info->name,
+						    "local",
+						    stash_label_base,
+						    autostash_msg.buf);
 			branch_info_release(&old_branch_info);
-			return ret;
+			strbuf_release(&old_commit_shortname);
+			strbuf_release(&autostash_msg);
+			return ret < 0 ? 1 : ret;
 		}
 	}
 
@@ -1231,8 +1181,30 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (opts->conflict_style >= 0) {
+		struct strbuf cfg = STRBUF_INIT;
+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
+			    conflict_style_name(opts->conflict_style));
+		git_config_push_parameter(cfg.buf);
+		strbuf_release(&cfg);
+	}
+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
+			    new_branch_info->name, "local",
+			    stash_label_base,
+			    autostash_msg.buf);
+
+	discard_index(the_repository->index);
+	if (repo_read_index(the_repository) < 0)
+		die(_("index file corrupt"));
+
+	if (created_autostash && !opts->quiet && new_branch_info->commit)
+		show_local_changes(&new_branch_info->commit->object,
+				   &opts->diff_options);
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
+	strbuf_release(&autostash_msg);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index 7c0376d9e4..480e8e6c0b 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4765,15 +4765,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however, applying it to carry\n"
+				  "forward your local changes resulted in conflicts:\n"
+				  "\n"
+				  " - You can try resolving them now.  If you resolved them\n"
+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
+				  "\n"
+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
+				  "   to deal with them right now, and later \"git stash pop\" to\n"
+				  "   recover your local changes.\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..e4e2cb19ce 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,30 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however, applying it to carry
+	forward your local changes resulted in conflicts:
+
+	 - You can try resolving them now.  If you resolved them
+	   successfully, discard the stash entry with "git stash drop".
+
+	 - Alternatively you can "git reset --hard" if you do not want
+	   to deal with them right now, and later "git stash pop" to
+	   recover your local changes.
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..c474c6759f 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -210,6 +210,214 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	fill a b X d e >two &&
+	git checkout --merge --conflict=zdiff3 simple &&
+
+	cat <<-EOF >expect &&
+	a
+	<<<<<<< simple
+	c
+	||||||| main
+	b
+	c
+	d
+	=======
+	b
+	X
+	d
+	>>>>>>> local
+	e
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m respects merge.conflictStyle config' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	test_config merge.conflictStyle diff3 &&
+	fill b d >two &&
+	git checkout -m simple &&
+
+	cat <<-EOF >expect &&
+	<<<<<<< simple
+	a
+	c
+	e
+	||||||| main
+	a
+	b
+	c
+	d
+	e
+	=======
+	b
+	d
+	>>>>>>> local
+	EOF
+	test_cmp expect two
+'
+
+test_expect_success 'checkout -m skips stash when no conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git stash list >stash-before &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same
+'
+
+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m stashes on truly conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m produces usable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "recover your local changes" actual &&
+	git checkout -f main &&
+	git stash pop &&
+	fill 1 2 3 4 5 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m autostash message includes target branch' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git checkout -m side >actual 2>&1 &&
+	git stash list >stash-list &&
+	test_grep "autostash while switching to .side." stash-list &&
+	git stash drop &&
+	git checkout -f main &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m stashes on staged conflicting changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	git add one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
+	git checkout -f main &&
+	git reset --hard &&
+	git clean -f &&
+
+	git checkout -b nonoverlap_base &&
+	fill a b c d >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b nonoverlap_child &&
+	fill a b c INSERTED d >file &&
+	git commit -a -m "insert line near end of file" &&
+
+	fill DIRTY a b c INSERTED d >file &&
+
+	git stash list >stash-before &&
+	git checkout -m nonoverlap_base 2>stderr &&
+	test_grep "Applied autostash" stderr &&
+	test_grep ! "resulted in conflicts" stderr &&
+
+	git stash list >stash-after &&
+	test_cmp stash-before stash-after &&
+
+	fill DIRTY a b c d >expect &&
+	test_cmp expect file &&
+
+	git checkout -f main &&
+	git branch -D nonoverlap_base &&
+	git branch -D nonoverlap_child
+'
+
+test_expect_success 'checkout -m -b skips stash with dirty tree' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git checkout -m -b newbranch >actual 2>&1 &&
+	test_grep ! "Created autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	git checkout main &&
+	git branch -D newbranch
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..cbef8a534e 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "your local changes resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v14 5/5] checkout -m: autostash when switching branches

[Phillip Wood]

Hi Harald

On 15/04/2026 17:24, Harald Nordgren via GitGitGadget wrote:
(trimming the documentation - I'll try and look at that next time)

> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index c80c62b37b..55c4db04c6 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -17,7 +17,6 @@
>   #include "merge-ll.h"
>   #include "lockfile.h"
>   #include "mem-pool.h"
> -#include "merge-ort-wrappers.h"
>   #include "object-file.h"
>   #include "object-name.h"
>   #include "odb.h"
> @@ -30,6 +29,7 @@
>   #include "repo-settings.h"
>   #include "resolve-undo.h"
>   #include "revision.h"
> +#include "sequencer.h"
>   #include "setup.h"
>   #include "submodule.h"
>   #include "symlinks.h"
> @@ -853,90 +853,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   		ret = unpack_trees(2, trees, &topts);
>   		clear_unpack_trees_porcelain(&topts);
>   		if (ret == -1) {
> -			/*
> -			 * Unpack couldn't do a trivial merge; either
> -			 * give up or do a real merge, depending on
> -			 * whether the merge flag was used.
> -			 */
> -			struct tree *work;
> -			struct tree *old_tree;
> -			struct merge_options o;
> -			struct strbuf sb = STRBUF_INIT;
> -			struct strbuf old_commit_shortname = STRBUF_INIT;
> -
> -			if (!opts->merge) {
> -				rollback_lock_file(&lock_file);
> -				return 1;
> -			}
> -
> -			/*
> -			 * Without old_branch_info->commit, the below is the same as
> -			 * the two-tree unpack we already tried and failed.
> -			 */
> -			if (!old_branch_info->commit) {
> -				rollback_lock_file(&lock_file);
> -				return 1;
> -			}
> -			old_tree = repo_get_commit_tree(the_repository,
> -							old_branch_info->commit);
> -
> -			if (repo_index_has_changes(the_repository, old_tree, &sb))
> -				die(_("cannot continue with staged changes in "
> -				      "the following files:\n%s"), sb.buf);
> -			strbuf_release(&sb);
> -
> -			/* Do more real merge */
> -
> -			/*
> -			 * We update the index fully, then write the
> -			 * tree from the index, then merge the new
> -			 * branch with the current tree, with the old
> -			 * branch as the base. Then we reset the index
> -			 * (but not the working tree) to the new
> -			 * branch, leaving the working tree as the
> -			 * merged version, but skipping unmerged
> -			 * entries in the index.
> -			 */
> -
> -			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
> -					0, 0);
> -			init_ui_merge_options(&o, the_repository);
> -			o.verbosity = 0;
> -			work = write_in_core_index_as_tree(the_repository,
> -							   the_repository->index);
> -
> -			ret = reset_tree(new_tree,
> -					 opts, 1,
> -					 writeout_error, new_branch_info);
> -			if (ret) {
> -				rollback_lock_file(&lock_file);
> -				return ret;
> -			}
> -			o.ancestor = old_branch_info->name;
> -			if (!old_branch_info->name) {
> -				strbuf_add_unique_abbrev(&old_commit_shortname,
> -							 &old_branch_info->commit->object.oid,
> -							 DEFAULT_ABBREV);
> -				o.ancestor = old_commit_shortname.buf;
> -			}
> -			o.branch1 = new_branch_info->name;
> -			o.branch2 = "local";
> -			o.conflict_style = opts->conflict_style;
> -			ret = merge_ort_nonrecursive(&o,
> -						     new_tree,
> -						     work,
> -						     old_tree);
> -			if (ret < 0)
> -				die(NULL);
> -			ret = reset_tree(new_tree,
> -					 opts, 0,
> -					 writeout_error, new_branch_info);
> -			strbuf_release(&o.obuf);
> -			strbuf_release(&old_commit_shortname);
> -			if (ret) {
> -				rollback_lock_file(&lock_file);
> -				return ret;
> -			}
> +			rollback_lock_file(&lock_file);
> +			return ret;

ret is -1 so we return the same value if unpack_trees() fails as do the 
checks at the top of the function do when they fail with "return 
error(...)". Therefore we cannot determine whether a failure of this 
function is due to unpack_trees() or not and so we wont know whether to 
autostash or not. You need to return a unique value here like -2 (or 
ideally a named constant)

>   		}
>   	}
>   
> @@ -1181,6 +1099,10 @@ static int switch_branches(const struct checkout_opts *opts,
>   	struct object_id rev;
>   	int flag, writeout_error = 0;
>   	int do_merge = 1;
> +	int created_autostash = 0;
> +	struct strbuf old_commit_shortname = STRBUF_INIT;
> +	struct strbuf autostash_msg = STRBUF_INIT;
> +	const char *stash_label_base = NULL;
>   
>   	trace2_cmd_mode("branch");
>   
> @@ -1218,11 +1140,39 @@ static int switch_branches(const struct checkout_opts *opts,
>   			do_merge = 0;
>   	}
>   
> +	if (old_branch_info.name)
> +		stash_label_base = old_branch_info.name;
> +	else if (old_branch_info.commit) {

Style: if one branch of an if statement has braces then all branch should.

> +		strbuf_add_unique_abbrev(&old_commit_shortname,
> +					 &old_branch_info.commit->object.oid,
> +					 DEFAULT_ABBREV);
> +		stash_label_base = old_commit_shortname.buf;
> +	}
> +
>   	if (do_merge) {
>   		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> +		if (ret == -1 && opts->merge) {
> +			strbuf_addf(&autostash_msg,
> +				    "autostash while switching to '%s'",
> +				    new_branch_info->name);
> +			create_autostash_ref(the_repository,
> +					     "CHECKOUT_AUTOSTASH_HEAD",
> +					     autostash_msg.buf, true);
> +			created_autostash = 1;
> +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> +		}
>   		if (ret) {
> +			if (created_autostash)
> +				apply_autostash_ref(the_repository,
> +						    "CHECKOUT_AUTOSTASH_HEAD",
> +						    new_branch_info->name,
> +						    "local",
> +						    stash_label_base,
> +						    autostash_msg.buf);

Good - now we only try to restore the stashed changes if we actually 
stashed. However we only restore the stashed changes if there was an 
error(). If there isn't an error we call update_refs_for_switch() before 
restoring them. It would be safer to restore them straight away in case 
that function ends up dying for any reason (though I think that's pretty 
unlikely)

	if (created_autostash) {
		if (opts->conflict_style >= 0)
			/* set up confilct style */
		apply_autostash_ref(...);
	}
	if (ret) {

>   			branch_info_release(&old_branch_info);
> -			return ret;
> +			strbuf_release(&old_commit_shortname);
> +			strbuf_release(&autostash_msg);
> +			return ret < 0 ? 1 : ret;

This changes the return value for all errors from merge_working_tree() - 
that's probably a good this as this value is used for the exit code and 
we don't really want an exit code of -1

>   		}
>   	}
>   
> @@ -1231,8 +1181,30 @@ static int switch_branches(const struct checkout_opts *opts,
>   
>   	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
>   
> +	if (opts->conflict_style >= 0) {
> +		struct strbuf cfg = STRBUF_INIT;
> +		strbuf_addf(&cfg, "merge.conflictStyle=%s",
> +			    conflict_style_name(opts->conflict_style));
> +		git_config_push_parameter(cfg.buf);
> +		strbuf_release(&cfg);
> +	}
> +	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
> +			    new_branch_info->name, "local",
> +			    stash_label_base,
> +			    autostash_msg.buf);> +	discard_index(the_repository->index);

As I said last time we should not be calling apply_autostash() if we 
have not created an autostash. We should also not discard and re-read 
the index if we haven't stashed. I do think we'd be better restoring the 
stashed changes in a single place as I said above.

> +	if (repo_read_index(the_repository) < 0)
> +		die(_("index file corrupt"));
> +
> +	if (created_autostash && !opts->quiet && new_branch_info->commit)
> +		show_local_changes(&new_branch_info->commit->object,
> +				   &opts->diff_options);

This shows the local changes, but it doesn't give any explanation of 
what the output is. For example when switching branches with a conflict 
I see

Your local changes are stashed, however, applying it to carry
forward your local changes resulted in conflicts:

  - You can try resolving them now.  If you resolved them
    successfully, discard the stash entry with "git stash drop".

  - Alternatively you can "git reset --hard" if you do not want
    to deal with them right now, and later "git stash pop" to
    recover your local changes.
M	t/t7201-co.sh

where the changes appear to be part of the advice message. Perhaps we 
should print a short (i.e. one sentance) message along the lines of

	The following paths have local changes

We should test what the user sees here as well.

> +
>   	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
>   	branch_info_release(&old_branch_info);
> +	strbuf_release(&old_commit_shortname);
> +	strbuf_release(&autostash_msg);
>   
>   	return ret || writeout_error;
>   }
> diff --git a/sequencer.c b/sequencer.c
> index 7c0376d9e4..480e8e6c0b 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4765,15 +4765,23 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
>   		strvec_push(&store.args, stash_oid);
>   		if (run_command(&store))
>   			ret = error(_("cannot store %s"), stash_oid);
> +		else if (attempt_apply)
> +			fprintf(stderr,
> +				_("Your local changes are stashed, however, applying it to carry\n"
> +				  "forward your local changes resulted in conflicts:\n"

I'm not sure we need to say "local changes" twice here

	Your local changes are stashed, however applying them
	resulted in conflicts.

> +				  "\n"
> +				  " - You can try resolving them now.  If you resolved them\n"
> +				  "   successfully, discard the stash entry with \"git stash drop\".\n"

s/resolved/resolve/

> +				  "\n"
> +				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
> +				  "   to deal with them right now, and later \"git stash pop\" to\n"
> +				  "   recover your local changes.\n"));

I find the bulleted list a bit odd, maybe

	You can either resolve the conflicts and then discard the stash
  	with "git stash drop", or, if you do not want to resolve them
	now, run "git reset --hard" and apply the local changes later by
	running "git stash pop"

would be better?

>   		else
>   			fprintf(stderr,
> -				_("%s\n"
> +				_("Autostash exists; creating a new stash entry.\n"
>   				  "Your changes are safe in the stash.\n"
>   				  "You can run \"git stash pop\" or"
> -				  " \"git stash drop\" at any time.\n"),
> -				attempt_apply ?
> -				_("Applying autostash resulted in conflicts.") :
> -				_("Autostash exists; creating a new stash entry."));
> +				  " \"git stash drop\" at any time.\n"));
>   	}
>   
>   	return ret;
> diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
> index ad3ba6a984..e4e2cb19ce 100755
> --- a/t/t3420-rebase-autostash.sh
> +++ b/t/t3420-rebase-autostash.sh
> @@ -61,18 +61,30 @@ create_expected_failure_apply () {
>   	First, rewinding head to replay your work on top of it...
>   	Applying: second commit
>   	Applying: third commit
> -	Applying autostash resulted in conflicts.
> -	Your changes are safe in the stash.
> -	You can run "git stash pop" or "git stash drop" at any time.
> +	Your local changes are stashed, however, applying it to carry
> +	forward your local changes resulted in conflicts:
> +
> +	 - You can try resolving them now.  If you resolved them
> +	   successfully, discard the stash entry with "git stash drop".
> +
> +	 - Alternatively you can "git reset --hard" if you do not want
> +	   to deal with them right now, and later "git stash pop" to
> +	   recover your local changes.
>   	EOF
>   }
>   
>   create_expected_failure_merge () {
>   	cat >expected <<-EOF
>   	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
> -	Applying autostash resulted in conflicts.
> -	Your changes are safe in the stash.
> -	You can run "git stash pop" or "git stash drop" at any time.
> +	Your local changes are stashed, however, applying it to carry
> +	forward your local changes resulted in conflicts:
> +
> +	 - You can try resolving them now.  If you resolved them
> +	   successfully, discard the stash entry with "git stash drop".
> +
> +	 - Alternatively you can "git reset --hard" if you do not want
> +	   to deal with them right now, and later "git stash pop" to
> +	   recover your local changes.
>   	Successfully rebased and updated refs/heads/rebased-feature-branch.
>   	EOF
>   }
> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..c474c6759f 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -210,6 +210,214 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
>   	test_cmp expect two
>   '
>   
> +test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	fill a b X d e >two &&
> +	git checkout --merge --conflict=zdiff3 simple &&

If I change "zdiff3" to "diff3" this test still passes which is 
disappointing. As the code that parses the conflict style is shared with 
other commands and we already have tests for --conflict=diff3 and 
--conflict=merge I'm not sure this test adds much.

> +
> +	cat <<-EOF >expect &&
> +	a
> +	<<<<<<< simple
> +	c
> +	||||||| main
> +	b
> +	c
> +	d
> +	=======
> +	b
> +	X
> +	d
> +	>>>>>>> local
> +	e
> +	EOF
> +	test_cmp expect two
> +'
> +
> +test_expect_success 'checkout -m respects merge.conflictStyle config' '

Looking at the existing tests, 'checkout with --merge, in diff3 -m 
style' and 'checkout --conflict=merge, overriding config' already test 
that we respect merge.conflictStyle and that --conflict overrides it so 
I don't see what new coverage this test adds.

> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	test_config merge.conflictStyle diff3 &&
> +	fill b d >two &&
> +	git checkout -m simple &&
> +
> +	cat <<-EOF >expect &&
> +	<<<<<<< simple
> +	a
> +	c
> +	e
> +	||||||| main
> +	a
> +	b
> +	c
> +	d
> +	e
> +	=======
> +	b
> +	d
> +	>>>>>>> local
> +	EOF
> +	test_cmp expect two
> +'
> +
> +test_expect_success 'checkout -m skips stash when no conflict' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git stash list >stash-before &&
> +	git checkout -m side >actual 2>&1 &&

file "same" is unchanged between branch "side" and "branch" main so we 
do not need to stash it.

> +	test_grep ! "Created autostash" actual &&
> +	git stash list >stash-after &&
> +	test_cmp stash-before stash-after &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same

Even if we created an autostash this test would not pick it up as the 
stash is not written to refs/stash unless there are merge conflicts and 
we don't print "Created autostash" even when we do create an autostash. 
The same is true for "checkout -m -b skips stash with dirty tree" below. 
I don't see how we can check that a stash was not created without using 
GIT_TRACE to see if we run "git stash". Even that is fragile as we might 
start stashing without forking a separate process in future.

> +'
> +
> +test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git add same &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same
> +'
> +
> +test_expect_success 'checkout -m stashes and applies on conflicting changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 6 7 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "Applied autostash" actual &&
> +	fill 1 2 3 4 5 6 7 >expect &&
> +	test_cmp expect one
> +'

I don't think the two tests above add any extra coverage when we have 
the one below so they can be deleted. Our test suite is slow enough 
already - we only need one test to fail for any given issue.

> +test_expect_success 'checkout -m with mixed staged and unstaged changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git add same &&
> +	fill 1 2 3 4 5 6 7 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "Applied autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same &&
> +	fill 1 2 3 4 5 6 7 >expect &&
> +	test_cmp expect one
> +'
> +
> +test_expect_success 'checkout -m stashes on truly conflicting changes' '

This use of conflicting is rather confusing - what's the difference 
between a conflicting change and a truly conflicting change?

I think a single test is sufficient to check that we create a valid 
stash entry

test_expect_success 'checkout -m stashes on truly conflicting changes' '
	git checkout -f main &&
	git clean -f &&

	fill 1 2 3 4 5 >one &&
	test_must_fail git checkout side 2>stderr &&
	test_grep "Your local changes" stderr &&
	git checkout -m side >actual 2>&1 &&
	test_grep ! "Created autostash" actual &&
	test_grep "resulted in conflicts" actual &&
	test_grep "git stash drop" actual &&
	test_grep "recover your local changes" actual &&
	git show --format=%B --diff-merges=1 refs/stash >actual &&
	sed /^index/d actual >actual.trimmed &&
	cat >expect <<-EOF &&
	On main: autostash while switching to ${SQ}side${SQ}
	diff --git a/one b/one
	--- a/one
	+++ b/one
	@@ -3,6 +3,3 @@
	 3
	 4
	 5
	-6
	-7
	-8
	EOF
	test_cmp expect actual.trimmed &&
'

Then we can delete from here to ...

> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	test_must_fail git checkout side 2>stderr &&
> +	test_grep "Your local changes" stderr &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "resulted in conflicts" actual &&
> +	test_grep "git stash drop" actual &&
> +	git stash drop &&
> +	git reset --hard
> +'
> +
> +test_expect_success 'checkout -m produces usable stash on conflict' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep "recover your local changes" actual &&
> +	git checkout -f main &&
> +	git stash pop &&
> +	fill 1 2 3 4 5 >expect &&
> +	test_cmp expect one
> +'
> +
> +test_expect_success 'checkout -m autostash message includes target branch' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	git stash list >stash-list &&
> +	test_grep "autostash while switching to .side." stash-list &&
> +	git stash drop &&
> +	git checkout -f main &&
> +	git reset --hard
> +'
> +
> +test_expect_success 'checkout -m stashes on staged conflicting changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	git add one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	test_grep "resulted in conflicts" actual &&
> +	test_grep "git stash drop" actual &&
> +	git stash drop &&
> +	git reset --hard
> +'

... here


> +test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '

I've no idea what this is trying to do - it looks more like it is 
testing that "git stash" works rather than anything to do with "git 
checkout"

> +	git checkout -f main &&
> +	git reset --hard &&
> +	git clean -f &&
> +
> +	git checkout -b nonoverlap_base &&
> +	fill a b c d >file &&
> +	git add file &&
> +	git commit -m "add file" &&
> +
> +	git checkout -b nonoverlap_child &&
> +	fill a b c INSERTED d >file &&
> +	git commit -a -m "insert line near end of file" &&
> +
> +	fill DIRTY a b c INSERTED d >file &&
> +
> +	git stash list >stash-before &&
> +	git checkout -m nonoverlap_base 2>stderr &&
> +	test_grep "Applied autostash" stderr &&
> +	test_grep ! "resulted in conflicts" stderr &&
> +
> +	git stash list >stash-after &&
> +	test_cmp stash-before stash-after &&
> +
> +	fill DIRTY a b c d >expect &&
> +	test_cmp expect file &&
> +
> +	git checkout -f main &&
> +	git branch -D nonoverlap_base &&
> +	git branch -D nonoverlap_child
> +'
> +
> +test_expect_success 'checkout -m -b skips stash with dirty tree' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git checkout -m -b newbranch >actual 2>&1 &&
> +	test_grep ! "Created autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same &&
> +	git checkout main &&
> +	git branch -D newbranch
> +'

As I said above I don't think this test is testing what it claims to.

I'd suggest adding the following test

test_expect_success 'checkout -m which would overwrite untracked file' '
	git checkout -f --detach main &&
	test_commit another-file &&
	git checkout HEAD^ &&
	>another-file.t &&
	test_must_fail git checkout -m @{-1} 2>err &&
	test_grep "another-file.t.*overwritten" err
'

which passes on master but fails with these patches applied. We need to 
make sure that we don't set "quiet" in unpack_tree_opts the second time 
we call merge_working_tree(). The test could be improved by adding some 
local changes.

This is looking better, but there are still a couple of problems that 
need addressing before it can be considered ready for merging.

Thanks

Phillip

>   test_expect_success 'switch to another branch while carrying a deletion' '
>   	git checkout -f main &&
>   	git reset --hard &&
> diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
> index 9838094b66..cbef8a534e 100755
> --- a/t/t7600-merge.sh
> +++ b/t/t7600-merge.sh
> @@ -914,7 +914,7 @@ test_expect_success 'merge with conflicted --autostash changes' '
>   	git diff >expect &&
>   	test_when_finished "test_might_fail git stash drop" &&
>   	git merge --autostash c3 2>err &&
> -	test_grep "Applying autostash resulted in conflicts." err &&
> +	test_grep "your local changes resulted in conflicts" err &&
>   	git show HEAD:file >merge-result &&
>   	test_cmp result.1-9 merge-result &&
>   	git stash show -p >actual &&
> diff --git a/xdiff-interface.c b/xdiff-interface.c
> index f043330f2a..5ee2b96d0a 100644
> --- a/xdiff-interface.c
> +++ b/xdiff-interface.c
> @@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
>   		return -1;
>   }
>   
> +const char *conflict_style_name(int style)
> +{
> +	switch (style) {
> +	case XDL_MERGE_DIFF3:
> +		return "diff3";
> +	case XDL_MERGE_ZEALOUS_DIFF3:
> +		return "zdiff3";
> +	default:
> +		return "merge";
> +	}
> +}
> +
>   int git_xmerge_style = -1;
>   
>   int git_xmerge_config(const char *var, const char *value,
> diff --git a/xdiff-interface.h b/xdiff-interface.h
> index fbc4ceec40..ce54e1c0e0 100644
> --- a/xdiff-interface.h
> +++ b/xdiff-interface.h
> @@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
>   void xdiff_clear_find_func(xdemitconf_t *xecfg);
>   struct config_context;
>   int parse_conflict_style_name(const char *value);
> +const char *conflict_style_name(int style);
>   int git_xmerge_config(const char *var, const char *value,
>   		      const struct config_context *ctx, void *cb);
>   extern int git_xmerge_style;

Comments on Phillip's review

[Harald Nordgren]

> ret is -1 so we return the same value if unpack_trees() fails as do the
> checks at the top of the function do when they fail with "return
> error(...)". Therefore we cannot determine whether a failure of this
> function is due to unpack_trees() or not and so we wont know whether to
> autostash or not. You need to return a unique value here like -2 (or
> ideally a named constant)

👍

> Good - now we only try to restore the stashed changes if we actually
> stashed. However we only restore the stashed changes if there was an
> error(). If there isn't an error we call update_refs_for_switch() before
> restoring them. It would be safer to restore them straight away in case
> that function ends up dying for any reason (though I think that's pretty
> unlikely)

I hope I understand correctly, the code becomes easier this way, so that's
nice!

> As I said last time we should not be calling apply_autostash() if we
> have not created an autostash. We should also not discard and re-read
> the index if we haven't stashed. I do think we'd be better restoring the
> stashed changes in a single place as I said above.

Makes sense.

> where the changes appear to be part of the advice message. Perhaps we
> should print a short (i.e. one sentance) message along the lines of
> 
>         The following paths have local changes
> 
> We should test what the user sees here as well.

Add that message.

Do you mean to test the full output? I'm not against it at all, but that
seems to be going against the convention of the other tests in this file.
But it would be a more robust test.

> I'm not sure we need to say "local changes" twice here

👍

> I find the bulleted list a bit odd, maybe
> 
>         You can either resolve the conflicts and then discard the stash
>         with "git stash drop", or, if you do not want to resolve them
>         now, run "git reset --hard" and apply the local changes later by
>         running "git stash pop"
> 
> would be better?

Much cleaner, thanks!

> we already have tests for --conflict=diff3 and
> --conflict=merge I'm not sure this test adds much.

Deleted.

> > +
> > +     cat <<-EOF >expect &&
> > +     a
> > +     <<<<<<< simple
> > +     c
> > +     ||||||| main
> > +     b
> > +     c
> > +     d
> > +     =======
> > +     b
> > +     X
> > +     d
> > +     >>>>>>> local
> > +     e
> > +     EOF
> > +     test_cmp expect two
> > +'
> > +
> > +test_expect_success 'checkout -m respects merge.conflictStyle config' '
> 
> Looking at the existing tests, 'checkout with --merge, in diff3 -m
> style' and 'checkout --conflict=merge, overriding config' already test
> that we respect merge.conflictStyle and that --conflict overrides it so
> I don't see what new coverage this test adds.

Deleted.

> > +test_expect_success 'checkout -m skips stash when no conflict' '
> > +     git checkout -f main &&
> > +     git clean -f &&
> > +
> > +     fill 0 x y z >same &&
> > +     git stash list >stash-before &&
> > +     git checkout -m side >actual 2>&1 &&
> 
> file "same" is unchanged between branch "side" and "branch" main so we
> do not need to stash it.

Deleted.

> > +     test_grep ! "Created autostash" actual &&
> > +     git stash list >stash-after &&
> > +     test_cmp stash-before stash-after &&
> > +     fill 0 x y z >expect &&
> > +     test_cmp expect same
> 
> Even if we created an autostash this test would not pick it up as the
> stash is not written to refs/stash unless there are merge conflicts and
> we don't print "Created autostash" even when we do create an autostash.
> The same is true for "checkout -m -b skips stash with dirty tree" below.
> I don't see how we can check that a stash was not created without using
> GIT_TRACE to see if we run "git stash". Even that is fragile as we might
> start stashing without forking a separate process in future.

Deleted.

> I don't think the two tests above add any extra coverage when we have
> the one below so they can be deleted. Our test suite is slow enough
> already - we only need one test to fail for any given issue.

Deleted.

> > +test_expect_success 'checkout -m stashes on truly conflicting changes' '
> 
> This use of conflicting is rather confusing - what's the difference
> between a conflicting change and a truly conflicting change?
> 
> I think a single test is sufficient to check that we create a valid
> stash entry

Updated.

> test_expect_success 'checkout -m which would overwrite untracked file' '
>         git checkout -f --detach main &&
>         test_commit another-file &&
>         git checkout HEAD^ &&
>         >another-file.t &&
>         test_must_fail git checkout -m @{-1} 2>err &&
>         test_grep "another-file.t.*overwritten" err
> '
> 
> which passes on master but fails with these patches applied. We need to
> make sure that we don't set "quiet" in unpack_tree_opts the second time
> we call merge_working_tree(). The test could be improved by adding some
> local changes.

Tricky to get right, the test if very good to have! I rewrote the logic now
to make this test pass, I hope it looks better now.


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

Hi Phillip, did you have a chance to look at the latest changes?


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Phillip Wood]

On 21/04/2026 08:53, Harald Nordgren wrote:
> Hi Phillip, did you have a chance to look at the latest changes?

Not yet, I should get round to it later this week. Junio is offline for 
at least the next week, I'll make sure I've reviewed them by the time he 
returns.

Thanks

Phillip

> 
> Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

👍


Harald

Re: [PATCH v14 0/5] checkout: 'autostash' for branch switching

[Phillip Wood]

Hi Harald

On 15/04/2026 17:24, Harald Nordgren via GitGitGadget wrote:
> Simplifying the tests in t/t3903-stash.sh according to Phillip Wood's
> comment. I believe everything sound be fixed now or responded to.

This is better than the last cover letter, but it would be helpful to 
describe the changes you have made rather than just say your responding 
to a reviewers comment. Junio has given some suggestions for 
coverletters to take inspiration from.

Also when you reply to messages can you try and keep the subject line 
please - nearly all the responses from you have the subject

Re: [PATCH] checkout: add --autostash option for branch switching

regardless of the message they're actually replying to. That makes it 
hard to see which message you're replying to.

I've left some comments on patch 5, it is definitely looking better but 
there are still a couple of things that need fixing.

Thanks

Phillip

> Also rebasing against upstream.
> 
> Harald Nordgren (5):
>    stash: add --label-ours, --label-theirs, --label-base for apply
>    sequencer: allow create_autostash to run silently
>    sequencer: teach autostash apply to take optional conflict marker
>      labels
>    checkout: rollback lock on early returns in merge_working_tree
>    checkout -m: autostash when switching branches
> 
>   Documentation/git-checkout.adoc |  58 ++++-----
>   Documentation/git-stash.adoc    |  11 +-
>   Documentation/git-switch.adoc   |  33 ++---
>   builtin/checkout.c              | 149 +++++++++++------------
>   builtin/commit.c                |   3 +-
>   builtin/merge.c                 |  15 ++-
>   builtin/stash.c                 |  28 +++--
>   sequencer.c                     |  73 ++++++++---
>   sequencer.h                     |   7 +-
>   t/t3420-rebase-autostash.sh     |  24 +++-
>   t/t3903-stash.sh                |  24 ++++
>   t/t7201-co.sh                   | 208 ++++++++++++++++++++++++++++++++
>   t/t7600-merge.sh                |   2 +-
>   xdiff-interface.c               |  12 ++
>   xdiff-interface.h               |   1 +
>   xdiff/xmerge.c                  |   6 +-
>   16 files changed, 483 insertions(+), 171 deletions(-)
> 
> 
> base-commit: 9f223ef1c026d91c7ac68cc0211bde255dda6199
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v14
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v14
> Pull-Request: https://github.com/git/git/pull/2234
> 
> Range-diff vs v13:
> 
>   1:  43bfdf2136 ! 1:  e18c25599a stash: add --label-ours, --label-theirs, --label-base for apply
>       @@ builtin/stash.c: static int branch_stash(int argc, const char **argv, const char
>         
>        
>         ## t/t3903-stash.sh ##
>       -@@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit conflicts' '
>       - 	)
>       +@@ t/t3903-stash.sh: setup_stash() {
>       + 	git add other-file &&
>       + 	test_tick &&
>       + 	git commit -m initial &&
>       ++	git tag initial &&
>       + 	echo 2 >file &&
>       + 	git add file &&
>       + 	echo 3 >file &&
>       +@@ t/t3903-stash.sh: test_expect_success 'stash.index=false overridden by --index' '
>       + 	test_cmp expect file
>         '
>         
>        +test_expect_success 'apply with custom conflict labels' '
>       -+	test_when_finished "git reset --hard && git stash drop" &&
>       -+	git reset --hard &&
>       ++	git reset --hard initial &&
>        +	test_commit label-base conflict-file base-content &&
>        +	echo stashed >conflict-file &&
>        +	git stash push -m "stashed" &&
>       @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
>        +'
>        +
>        +test_expect_success 'apply with empty conflict labels' '
>       -+	test_when_finished "git reset --hard && git stash drop" &&
>       -+	git reset --hard &&
>       ++	git reset --hard initial &&
>        +	test_commit empty-label-base conflict-file base-content &&
>        +	echo stashed >conflict-file &&
>        +	git stash push -m "stashed" &&
>       @@ t/t3903-stash.sh: test_expect_success 'restore untracked files even when we hit
>        +	test_grep "^>>>>>>>$" conflict-file
>        +'
>        +
>       - test_expect_success 'stash create reports a locked index' '
>       - 	test_when_finished "rm -rf repo" &&
>       - 	git init repo &&
>       + test_done
>        
>         ## xdiff/xmerge.c ##
>        @@ xdiff/xmerge.c: static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
>   2:  7f3c32f5e9 = 2:  ce29b10264 sequencer: allow create_autostash to run silently
>   3:  b279d1dac8 = 3:  73051d1762 sequencer: teach autostash apply to take optional conflict marker labels
>   4:  04869314ec = 4:  191058d8e3 checkout: rollback lock on early returns in merge_working_tree
>   5:  4b3c6025ac = 5:  86f33df1eb checkout -m: autostash when switching branches
> 

[PATCH v15 0/5] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

 * When the initial merge fails, the caller now knows for sure it was a
   conflict (not some unrelated error) before kicking off the autostash.

 * If the second attempt also fails, the user now actually sees why.
   Previously errors like "would be overwritten by checkout" were being
   swallowed.

 * The stash is reapplied right after the second attempt, so it won't get
   left behind if something else goes wrong later in the checkout.

 * A couple of clean-up steps only run when we actually stashed, so regular
   checkouts aren't paying for work they don't need.

 * Added a small header "The following paths have local changes:" before the
   list of changed files, so it doesn't look like part of the conflict
   advice above it.

 * Reworded the conflict advice into a single paragraph. Feels less shouty
   and doesn't say "local changes" three times.

 * Trimmed and consolidated tests in t7201. A bunch of the old ones couldn't
   actually fail, or were really testing other things; the conflict-path
   tests are now a single test that checks the stash entry directly.

Harald Nordgren (5):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: rollback lock on early returns in merge_working_tree
  checkout -m: autostash when switching branches

 Documentation/git-checkout.adoc |  58 +++++------
 Documentation/git-stash.adoc    |  11 ++-
 Documentation/git-switch.adoc   |  33 +++----
 builtin/checkout.c              | 165 +++++++++++++++-----------------
 builtin/commit.c                |   3 +-
 builtin/merge.c                 |  15 ++-
 builtin/stash.c                 |  28 ++++--
 sequencer.c                     |  69 +++++++++----
 sequencer.h                     |   7 +-
 t/t3420-rebase-autostash.sh     |  16 ++--
 t/t3903-stash.sh                |  24 +++++
 t/t7201-co.sh                   |  61 +++++++++++-
 t/t7600-merge.sh                |   3 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 16 files changed, 335 insertions(+), 177 deletions(-)


base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v15
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v15
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v14:

 1:  e18c25599a = 1:  aba8e6a9dc stash: add --label-ours, --label-theirs, --label-base for apply
 2:  ce29b10264 = 2:  89e0bfa803 sequencer: allow create_autostash to run silently
 3:  73051d1762 = 3:  a428ce7328 sequencer: teach autostash apply to take optional conflict marker labels
 4:  191058d8e3 = 4:  f358424085 checkout: rollback lock on early returns in merge_working_tree
 5:  86f33df1eb ! 5:  96b14db827 checkout -m: autostash when switching branches
     @@ builtin/checkout.c
       #include "setup.h"
       #include "submodule.h"
       #include "symlinks.h"
     +@@ builtin/checkout.c: struct checkout_opts {
     + 	.auto_advance = 1, \
     + }
     + 
     ++#define MERGE_WORKING_TREE_UNPACK_FAILED (-2)
     ++
     + struct branch_info {
     + 	char *name; /* The short name used */
     + 	char *path; /* The full name of a real branch */
     +@@ builtin/checkout.c: static void setup_branch_path(struct branch_info *branch)
     + 
     + static void init_topts(struct unpack_trees_options *topts, int merge,
     + 		       int show_progress, int overwrite_ignore,
     +-		       struct commit *old_commit)
     ++		       struct commit *old_commit, bool show_unpack_errors)
     + {
     + 	memset(topts, 0, sizeof(*topts));
     + 	topts->head_idx = -1;
     +@@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, int merge,
     + 	topts->initial_checkout = is_index_unborn(the_repository->index);
     + 	topts->update = 1;
     + 	topts->merge = 1;
     +-	topts->quiet = merge && old_commit;
     ++	topts->quiet = merge && old_commit && !show_unpack_errors;
     + 	topts->verbose_update = show_progress;
     + 	topts->fn = twoway_merge;
     + 	topts->preserve_ignored = !overwrite_ignore;
     +@@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, int merge,
     + static int merge_working_tree(const struct checkout_opts *opts,
     + 			      struct branch_info *old_branch_info,
     + 			      struct branch_info *new_branch_info,
     +-			      int *writeout_error)
     ++			      int *writeout_error,
     ++			      bool show_unpack_errors)
     + {
     + 	int ret;
     + 	struct lock_file lock_file = LOCK_INIT;
     +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     + 
     + 		/* 2-way merge to the new branch */
     + 		init_topts(&topts, opts->merge, opts->show_progress,
     +-			   opts->overwrite_ignore, old_branch_info->commit);
     ++			   opts->overwrite_ignore, old_branch_info->commit,
     ++			   show_unpack_errors);
     + 		init_checkout_metadata(&topts.meta, new_branch_info->refname,
     + 				       new_branch_info->commit ?
     + 				       &new_branch_info->commit->object.oid :
      @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
       		ret = unpack_trees(2, trees, &topts);
       		clear_unpack_trees_porcelain(&topts);
     @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
      -				return ret;
      -			}
      +			rollback_lock_file(&lock_file);
     -+			return ret;
     ++			return MERGE_WORKING_TREE_UNPACK_FAILED;
       		}
       	}
       
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       			do_merge = 0;
       	}
       
     -+	if (old_branch_info.name)
     ++	if (old_branch_info.name) {
      +		stash_label_base = old_branch_info.name;
     -+	else if (old_branch_info.commit) {
     ++	} else if (old_branch_info.commit) {
      +		strbuf_add_unique_abbrev(&old_commit_shortname,
      +					 &old_branch_info.commit->object.oid,
      +					 DEFAULT_ABBREV);
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +	}
      +
       	if (do_merge) {
     - 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
     -+		if (ret == -1 && opts->merge) {
     +-		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
     ++		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
     ++					 &writeout_error, false);
     ++		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
      +			strbuf_addf(&autostash_msg,
      +				    "autostash while switching to '%s'",
      +				    new_branch_info->name);
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +					     "CHECKOUT_AUTOSTASH_HEAD",
      +					     autostash_msg.buf, true);
      +			created_autostash = 1;
     -+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
     ++			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
     ++						 &writeout_error, true);
     ++		}
     ++		if (created_autostash) {
     ++			if (opts->conflict_style >= 0) {
     ++				struct strbuf cfg = STRBUF_INIT;
     ++				strbuf_addf(&cfg, "merge.conflictStyle=%s",
     ++					    conflict_style_name(opts->conflict_style));
     ++				git_config_push_parameter(cfg.buf);
     ++				strbuf_release(&cfg);
     ++			}
     ++			apply_autostash_ref(the_repository,
     ++					    "CHECKOUT_AUTOSTASH_HEAD",
     ++					    new_branch_info->name,
     ++					    "local",
     ++					    stash_label_base,
     ++					    autostash_msg.buf);
      +		}
       		if (ret) {
     -+			if (created_autostash)
     -+				apply_autostash_ref(the_repository,
     -+						    "CHECKOUT_AUTOSTASH_HEAD",
     -+						    new_branch_info->name,
     -+						    "local",
     -+						    stash_label_base,
     -+						    autostash_msg.buf);
       			branch_info_release(&old_branch_info);
      -			return ret;
      +			strbuf_release(&old_commit_shortname);
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       
       	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
       
     -+	if (opts->conflict_style >= 0) {
     -+		struct strbuf cfg = STRBUF_INIT;
     -+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
     -+			    conflict_style_name(opts->conflict_style));
     -+		git_config_push_parameter(cfg.buf);
     -+		strbuf_release(&cfg);
     ++	if (created_autostash) {
     ++		discard_index(the_repository->index);
     ++		if (repo_read_index(the_repository) < 0)
     ++			die(_("index file corrupt"));
     ++
     ++		if (!opts->quiet && new_branch_info->commit) {
     ++			printf(_("The following paths have local changes:\n"));
     ++			show_local_changes(&new_branch_info->commit->object,
     ++					   &opts->diff_options);
     ++		}
      +	}
     -+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
     -+			    new_branch_info->name, "local",
     -+			    stash_label_base,
     -+			    autostash_msg.buf);
     -+
     -+	discard_index(the_repository->index);
     -+	if (repo_read_index(the_repository) < 0)
     -+		die(_("index file corrupt"));
     -+
     -+	if (created_autostash && !opts->quiet && new_branch_info->commit)
     -+		show_local_changes(&new_branch_info->commit->object,
     -+				   &opts->diff_options);
      +
       	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
       	branch_info_release(&old_branch_info);
     @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
       			ret = error(_("cannot store %s"), stash_oid);
      +		else if (attempt_apply)
      +			fprintf(stderr,
     -+				_("Your local changes are stashed, however, applying it to carry\n"
     -+				  "forward your local changes resulted in conflicts:\n"
     -+				  "\n"
     -+				  " - You can try resolving them now.  If you resolved them\n"
     -+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
     -+				  "\n"
     -+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
     -+				  "   to deal with them right now, and later \"git stash pop\" to\n"
     -+				  "   recover your local changes.\n"));
     ++				_("Your local changes are stashed, however applying them\n"
     ++				  "resulted in conflicts.  You can either resolve the conflicts\n"
     ++				  "and then discard the stash with \"git stash drop\", or, if you\n"
     ++				  "do not want to resolve them now, run \"git reset --hard\" and\n"
     ++				  "apply the local changes later by running \"git stash pop\".\n"));
       		else
       			fprintf(stderr,
      -				_("%s\n"
     @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {
      -	Applying autostash resulted in conflicts.
      -	Your changes are safe in the stash.
      -	You can run "git stash pop" or "git stash drop" at any time.
     -+	Your local changes are stashed, however, applying it to carry
     -+	forward your local changes resulted in conflicts:
     -+
     -+	 - You can try resolving them now.  If you resolved them
     -+	   successfully, discard the stash entry with "git stash drop".
     -+
     -+	 - Alternatively you can "git reset --hard" if you do not want
     -+	   to deal with them right now, and later "git stash pop" to
     -+	   recover your local changes.
     ++	Your local changes are stashed, however applying them
     ++	resulted in conflicts.  You can either resolve the conflicts
     ++	and then discard the stash with "git stash drop", or, if you
     ++	do not want to resolve them now, run "git reset --hard" and
     ++	apply the local changes later by running "git stash pop".
       	EOF
       }
       
     @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {
      -	Applying autostash resulted in conflicts.
      -	Your changes are safe in the stash.
      -	You can run "git stash pop" or "git stash drop" at any time.
     -+	Your local changes are stashed, however, applying it to carry
     -+	forward your local changes resulted in conflicts:
     -+
     -+	 - You can try resolving them now.  If you resolved them
     -+	   successfully, discard the stash entry with "git stash drop".
     -+
     -+	 - Alternatively you can "git reset --hard" if you do not want
     -+	   to deal with them right now, and later "git stash pop" to
     -+	   recover your local changes.
     ++	Your local changes are stashed, however applying them
     ++	resulted in conflicts.  You can either resolve the conflicts
     ++	and then discard the stash with "git stash drop", or, if you
     ++	do not want to resolve them now, run "git reset --hard" and
     ++	apply the local changes later by running "git stash pop".
       	Successfully rebased and updated refs/heads/rebased-feature-branch.
       	EOF
       }
      
       ## t/t7201-co.sh ##
     +@@ t/t7201-co.sh: test_expect_success 'checkout -m with dirty tree' '
     + 
     + 	test "$(git symbolic-ref HEAD)" = "refs/heads/side" &&
     + 
     +-	printf "M\t%s\n" one >expect.messages &&
     ++	printf "The following paths have local changes:\nM\t%s\n" one >expect.messages &&
     + 	test_cmp expect.messages messages &&
     + 
     + 	fill "M	one" "A	three" "D	two" >expect.main &&
      @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
       	test_cmp expect two
       '
       
     -+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
     -+	git checkout -f main &&
     -+	git reset --hard &&
     -+	git clean -f &&
     -+
     -+	fill a b X d e >two &&
     -+	git checkout --merge --conflict=zdiff3 simple &&
     -+
     -+	cat <<-EOF >expect &&
     -+	a
     -+	<<<<<<< simple
     -+	c
     -+	||||||| main
     -+	b
     -+	c
     -+	d
     -+	=======
     -+	b
     -+	X
     -+	d
     -+	>>>>>>> local
     -+	e
     -+	EOF
     -+	test_cmp expect two
     -+'
     -+
     -+test_expect_success 'checkout -m respects merge.conflictStyle config' '
     -+	git checkout -f main &&
     -+	git reset --hard &&
     -+	git clean -f &&
     -+
     -+	test_config merge.conflictStyle diff3 &&
     -+	fill b d >two &&
     -+	git checkout -m simple &&
     -+
     -+	cat <<-EOF >expect &&
     -+	<<<<<<< simple
     -+	a
     -+	c
     -+	e
     -+	||||||| main
     -+	a
     -+	b
     -+	c
     -+	d
     -+	e
     -+	=======
     -+	b
     -+	d
     -+	>>>>>>> local
     -+	EOF
     -+	test_cmp expect two
     -+'
     -+
     -+test_expect_success 'checkout -m skips stash when no conflict' '
     -+	git checkout -f main &&
     -+	git clean -f &&
     -+
     -+	fill 0 x y z >same &&
     -+	git stash list >stash-before &&
     -+	git checkout -m side >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	git stash list >stash-after &&
     -+	test_cmp stash-before stash-after &&
     -+	fill 0 x y z >expect &&
     -+	test_cmp expect same
     -+'
     -+
     -+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
     -+	git checkout -f main &&
     -+	git clean -f &&
     -+
     -+	fill 0 x y z >same &&
     -+	git add same &&
     -+	git checkout -m side >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	fill 0 x y z >expect &&
     -+	test_cmp expect same
     -+'
     -+
     -+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
     -+	git checkout -f main &&
     -+	git clean -f &&
     -+
     -+	fill 1 2 3 4 5 6 7 >one &&
     -+	git checkout -m side >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	test_grep "Applied autostash" actual &&
     -+	fill 1 2 3 4 5 6 7 >expect &&
     -+	test_cmp expect one
     -+'
     -+
      +test_expect_success 'checkout -m with mixed staged and unstaged changes' '
      +	git checkout -f main &&
      +	git clean -f &&
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	git add same &&
      +	fill 1 2 3 4 5 6 7 >one &&
      +	git checkout -m side >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
      +	test_grep "Applied autostash" actual &&
      +	fill 0 x y z >expect &&
      +	test_cmp expect same &&
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	test_cmp expect one
      +'
      +
     -+test_expect_success 'checkout -m stashes on truly conflicting changes' '
     ++test_expect_success 'checkout -m creates a recoverable stash on conflict' '
      +	git checkout -f main &&
      +	git clean -f &&
      +
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	test_must_fail git checkout side 2>stderr &&
      +	test_grep "Your local changes" stderr &&
      +	git checkout -m side >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
      +	test_grep "resulted in conflicts" actual &&
      +	test_grep "git stash drop" actual &&
     ++	test_grep "git stash pop" actual &&
     ++	test_grep "The following paths have local changes" actual &&
     ++	git show --format=%B --diff-merges=1 refs/stash >actual &&
     ++	sed /^index/d actual >actual.trimmed &&
     ++	cat >expect <<-EOF &&
     ++	On main: autostash while switching to ${SQ}side${SQ}
     ++
     ++	diff --git a/one b/one
     ++	--- a/one
     ++	+++ b/one
     ++	@@ -3,6 +3,3 @@
     ++	 3
     ++	 4
     ++	 5
     ++	-6
     ++	-7
     ++	-8
     ++	EOF
     ++	test_cmp expect actual.trimmed &&
      +	git stash drop &&
      +	git reset --hard
      +'
      +
     -+test_expect_success 'checkout -m produces usable stash on conflict' '
     -+	git checkout -f main &&
     -+	git clean -f &&
     -+
     ++test_expect_success 'checkout -m which would overwrite untracked file' '
     ++	git checkout -f --detach main &&
     ++	test_commit another-file &&
     ++	git checkout HEAD^ &&
     ++	>another-file.t &&
      +	fill 1 2 3 4 5 >one &&
     -+	git checkout -m side >actual 2>&1 &&
     -+	test_grep "recover your local changes" actual &&
     -+	git checkout -f main &&
     -+	git stash pop &&
     -+	fill 1 2 3 4 5 >expect &&
     -+	test_cmp expect one
     -+'
     -+
     -+test_expect_success 'checkout -m autostash message includes target branch' '
     -+	git checkout -f main &&
     -+	git clean -f &&
     -+
     -+	fill 1 2 3 4 5 >one &&
     -+	git checkout -m side >actual 2>&1 &&
     -+	git stash list >stash-list &&
     -+	test_grep "autostash while switching to .side." stash-list &&
     -+	git stash drop &&
     -+	git checkout -f main &&
     -+	git reset --hard
     -+'
     -+
     -+test_expect_success 'checkout -m stashes on staged conflicting changes' '
     -+	git checkout -f main &&
     -+	git clean -f &&
     -+
     -+	fill 1 2 3 4 5 >one &&
     -+	git add one &&
     -+	git checkout -m side >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	test_grep "resulted in conflicts" actual &&
     -+	test_grep "git stash drop" actual &&
     -+	git stash drop &&
     -+	git reset --hard
     -+'
     -+
     -+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
     -+	git checkout -f main &&
     -+	git reset --hard &&
     -+	git clean -f &&
     -+
     -+	git checkout -b nonoverlap_base &&
     -+	fill a b c d >file &&
     -+	git add file &&
     -+	git commit -m "add file" &&
     -+
     -+	git checkout -b nonoverlap_child &&
     -+	fill a b c INSERTED d >file &&
     -+	git commit -a -m "insert line near end of file" &&
     -+
     -+	fill DIRTY a b c INSERTED d >file &&
     -+
     -+	git stash list >stash-before &&
     -+	git checkout -m nonoverlap_base 2>stderr &&
     -+	test_grep "Applied autostash" stderr &&
     -+	test_grep ! "resulted in conflicts" stderr &&
     -+
     -+	git stash list >stash-after &&
     -+	test_cmp stash-before stash-after &&
     -+
     -+	fill DIRTY a b c d >expect &&
     -+	test_cmp expect file &&
     -+
     -+	git checkout -f main &&
     -+	git branch -D nonoverlap_base &&
     -+	git branch -D nonoverlap_child
     -+'
     -+
     -+test_expect_success 'checkout -m -b skips stash with dirty tree' '
     -+	git checkout -f main &&
     -+	git clean -f &&
     -+
     -+	fill 0 x y z >same &&
     -+	git checkout -m -b newbranch >actual 2>&1 &&
     -+	test_grep ! "Created autostash" actual &&
     -+	fill 0 x y z >expect &&
     -+	test_cmp expect same &&
     -+	git checkout main &&
     -+	git branch -D newbranch
     ++	test_must_fail git checkout -m @{-1} 2>err &&
     ++	test_grep "would be overwritten by checkout" err &&
     ++	test_grep "another-file.t" err
      +'
      +
       test_expect_success 'switch to another branch while carrying a deletion' '
     @@ t/t7600-merge.sh: test_expect_success 'merge with conflicted --autostash changes
       	test_when_finished "test_might_fail git stash drop" &&
       	git merge --autostash c3 2>err &&
      -	test_grep "Applying autostash resulted in conflicts." err &&
     -+	test_grep "your local changes resulted in conflicts" err &&
     ++	test_grep "applying them" err &&
     ++	test_grep "resulted in conflicts" err &&
       	git show HEAD:file >merge-result &&
       	test_cmp result.1-9 merge-result &&
       	git stash show -p >actual &&

-- 
gitgitgadget

[PATCH v15 1/5] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 28 ++++++++++++++++++++--------
 t/t3903-stash.sh             | 24 ++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 57 insertions(+), 12 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..32dbc97b47 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -591,7 +591,9 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 }
 
 static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+			  int index, int quiet,
+			  const char *label_ours, const char *label_theirs,
+			  const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +645,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -723,11 +725,18 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +746,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash(prefix, &info, index, quiet,
+			     label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
@@ -836,7 +846,8 @@ static int pop_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info_assert(&info, argc, argv))
 		goto cleanup;
 
-	if ((ret = do_apply_stash(prefix, &info, index, quiet)))
+	if ((ret = do_apply_stash(prefix, &info, index, quiet,
+				  NULL, NULL, NULL)))
 		printf_ln(_("The stash entry is kept in case "
 			    "you need it again."));
 	else
@@ -877,7 +888,8 @@ static int branch_stash(int argc, const char **argv, const char *prefix,
 	strvec_push(&cp.args, oid_to_hex(&info.b_commit));
 	ret = run_command(&cp);
 	if (!ret)
-		ret = do_apply_stash(prefix, &info, 1, 0);
+		ret = do_apply_stash(prefix, &info, 1, 0,
+				     NULL, NULL, NULL);
 	if (!ret && info.is_stash_ref)
 		ret = do_drop_stash(&info, 0);
 
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..bdaad22e1f 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -56,6 +56,7 @@ setup_stash() {
 	git add other-file &&
 	test_tick &&
 	git commit -m initial &&
+	git tag initial &&
 	echo 2 >file &&
 	git add file &&
 	echo 3 >file &&
@@ -1790,4 +1791,27 @@ test_expect_success 'stash.index=false overridden by --index' '
 	test_cmp expect file
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git reset --hard initial &&
+	test_commit label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit label-upstream conflict-file upstream-content &&
+	test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+	test_grep "^<<<<<<< UP" conflict-file &&
+	test_grep "^||||||| Stash base" conflict-file &&
+	test_grep "^>>>>>>> STASH" conflict-file
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git reset --hard initial &&
+	test_commit empty-label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit empty-label-upstream conflict-file upstream-content &&
+	test_must_fail git stash apply --label-ours= --label-theirs= &&
+	test_grep "^<<<<<<<$" conflict-file &&
+	test_grep "^>>>>>>>$" conflict-file
+'
+
 test_done
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

Re: [PATCH v15 1/5] stash: add --label-ours, --label-theirs, --label-base for apply

[Phillip Wood]

Hi Harald

On 24/04/2026 22:10, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Allow callers of "git stash apply" to pass custom labels for conflict
> markers instead of the default "Updated upstream" and "Stashed changes".
> Document the new options and add a test.

This all looks good, just one small comment below

> -	o.branch1 = "Updated upstream";
> -	o.branch2 = "Stashed changes";
> -	o.ancestor = "Stash base";
> +	o.branch1 = label_ours ? label_ours : "Updated upstream";
> +	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
> +	o.ancestor = label_base ? label_base : "Stash base";

This uses the existing label which is sensible, but I wonder if "Stash 
HEAD" would be a better choice as the merge base is always HEAD commit 
that the stash is based on.

We can always change that later

Thanks

Phillip

>   
>   	if (oideq(&info->b_tree, &c_tree))
>   		o.branch1 = "Version stash was based on";
> @@ -723,11 +725,18 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
>   	int ret = -1;
>   	int quiet = 0;
>   	int index = use_index;
> +	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
>   	struct stash_info info = STASH_INFO_INIT;
>   	struct option options[] = {
>   		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
>   		OPT_BOOL(0, "index", &index,
>   			 N_("attempt to recreate the index")),
> +		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
> +			   N_("label for the upstream side in conflict markers")),
> +		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
> +			   N_("label for the stashed side in conflict markers")),
> +		OPT_STRING(0, "label-base", &label_base, N_("label"),
> +			   N_("label for the base in diff3 conflict markers")),
>   		OPT_END()
>   	};
>   
> @@ -737,7 +746,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
>   	if (get_stash_info(&info, argc, argv))
>   		goto cleanup;
>   
> -	ret = do_apply_stash(prefix, &info, index, quiet);
> +	ret = do_apply_stash(prefix, &info, index, quiet,
> +			     label_ours, label_theirs, label_base);
>   cleanup:
>   	free_stash_info(&info);
>   	return ret;
> @@ -836,7 +846,8 @@ static int pop_stash(int argc, const char **argv, const char *prefix,
>   	if (get_stash_info_assert(&info, argc, argv))
>   		goto cleanup;
>   
> -	if ((ret = do_apply_stash(prefix, &info, index, quiet)))
> +	if ((ret = do_apply_stash(prefix, &info, index, quiet,
> +				  NULL, NULL, NULL)))
>   		printf_ln(_("The stash entry is kept in case "
>   			    "you need it again."));
>   	else
> @@ -877,7 +888,8 @@ static int branch_stash(int argc, const char **argv, const char *prefix,
>   	strvec_push(&cp.args, oid_to_hex(&info.b_commit));
>   	ret = run_command(&cp);
>   	if (!ret)
> -		ret = do_apply_stash(prefix, &info, 1, 0);
> +		ret = do_apply_stash(prefix, &info, 1, 0,
> +				     NULL, NULL, NULL);
>   	if (!ret && info.is_stash_ref)
>   		ret = do_drop_stash(&info, 0);
>   
> diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
> index 70879941c2..bdaad22e1f 100755
> --- a/t/t3903-stash.sh
> +++ b/t/t3903-stash.sh
> @@ -56,6 +56,7 @@ setup_stash() {
>   	git add other-file &&
>   	test_tick &&
>   	git commit -m initial &&
> +	git tag initial &&
>   	echo 2 >file &&
>   	git add file &&
>   	echo 3 >file &&
> @@ -1790,4 +1791,27 @@ test_expect_success 'stash.index=false overridden by --index' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success 'apply with custom conflict labels' '
> +	git reset --hard initial &&
> +	test_commit label-base conflict-file base-content &&
> +	echo stashed >conflict-file &&
> +	git stash push -m "stashed" &&
> +	test_commit label-upstream conflict-file upstream-content &&
> +	test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
> +	test_grep "^<<<<<<< UP" conflict-file &&
> +	test_grep "^||||||| Stash base" conflict-file &&
> +	test_grep "^>>>>>>> STASH" conflict-file
> +'
> +
> +test_expect_success 'apply with empty conflict labels' '
> +	git reset --hard initial &&
> +	test_commit empty-label-base conflict-file base-content &&
> +	echo stashed >conflict-file &&
> +	git stash push -m "stashed" &&
> +	test_commit empty-label-upstream conflict-file upstream-content &&
> +	test_must_fail git stash apply --label-ours= --label-theirs= &&
> +	test_grep "^<<<<<<<$" conflict-file &&
> +	test_grep "^>>>>>>>$" conflict-file
> +'
> +
>   test_done
> diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
> index 29dad98c49..659ad4ec97 100644
> --- a/xdiff/xmerge.c
> +++ b/xdiff/xmerge.c
> @@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
>   			      int size, int i, int style,
>   			      xdmerge_t *m, char *dest, int marker_size)
>   {
> -	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
> -	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
> -	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
> +	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
> +	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
> +	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
>   	int needs_cr = is_cr_needed(xe1, xe2, m);
>   
>   	if (marker_size <= 0)

[PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> This uses the existing label which is sensible, but I wonder if "Stash
> HEAD" would be a better choice as the merge base is always HEAD commit
> that the stash is based on.
> 
> We can always change that later

Yeah, seems better to do later.


Harald

[PATCH v15 2/5] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/merge.c |  6 ++++--
 sequencer.c     | 17 +++++++++++------
 sequencer.h     |  3 ++-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index 2cbce56f8d..3ebe190ef1 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1672,7 +1672,8 @@ int cmd_merge(int argc,
 		}
 
 		if (autostash)
-			create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					     NULL, false);
 		if (checkout_fast_forward(the_repository,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
@@ -1764,7 +1765,8 @@ int cmd_merge(int argc,
 		die_ff_impossible();
 
 	if (autostash)
-		create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				     NULL, false);
 
 	/* We are going to make a new commit. */
 	git_committer_info(IDENT_STRICT);
diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..ff5258f481 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,9 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      const char *message,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4679,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
 		struct object_id oid;
 
 		strvec_pushl(&stash.args,
-			     "stash", "create", "autostash", NULL);
+			     "stash", "create",
+			     message ? message : "autostash", NULL);
 		stash.git_cmd = 1;
 		stash.no_stdin = 1;
 		strbuf_reset(&buf);
@@ -4702,7 +4705,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4718,13 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, NULL, false);
 }
 
-void create_autostash_ref(struct repository *r, const char *refname)
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..02d2d9db06 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -229,7 +229,8 @@ void commit_post_rewrite(struct repository *r,
 			 const struct object_id *new_head);
 
 void create_autostash(struct repository *r, const char *path);
-void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

Re: [PATCH v15 2/5] sequencer: allow create_autostash to run silently

[Phillip Wood]

Hi Harald

This looks good

Thanks

Phillip

On 24/04/2026 22:10, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add a silent parameter to create_autostash_internal and introduce
> create_autostash_ref_silent so that callers can create an autostash
> without printing the "Created autostash" message.
> 
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>   builtin/merge.c |  6 ++++--
>   sequencer.c     | 17 +++++++++++------
>   sequencer.h     |  3 ++-
>   3 files changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/builtin/merge.c b/builtin/merge.c
> index 2cbce56f8d..3ebe190ef1 100644
> --- a/builtin/merge.c
> +++ b/builtin/merge.c
> @@ -1672,7 +1672,8 @@ int cmd_merge(int argc,
>   		}
>   
>   		if (autostash)
> -			create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
> +			create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
> +					     NULL, false);
>   		if (checkout_fast_forward(the_repository,
>   					  &head_commit->object.oid,
>   					  &commit->object.oid,
> @@ -1764,7 +1765,8 @@ int cmd_merge(int argc,
>   		die_ff_impossible();
>   
>   	if (autostash)
> -		create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
> +		create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
> +				     NULL, false);
>   
>   	/* We are going to make a new commit. */
>   	git_committer_info(IDENT_STRICT);
> diff --git a/sequencer.c b/sequencer.c
> index b7d8dca47f..ff5258f481 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4657,7 +4657,9 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
>   
>   static void create_autostash_internal(struct repository *r,
>   				      const char *path,
> -				      const char *refname)
> +				      const char *refname,
> +				      const char *message,
> +				      bool silent)
>   {
>   	struct strbuf buf = STRBUF_INIT;
>   	struct lock_file lock_file = LOCK_INIT;
> @@ -4679,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
>   		struct object_id oid;
>   
>   		strvec_pushl(&stash.args,
> -			     "stash", "create", "autostash", NULL);
> +			     "stash", "create",
> +			     message ? message : "autostash", NULL);
>   		stash.git_cmd = 1;
>   		stash.no_stdin = 1;
>   		strbuf_reset(&buf);
> @@ -4702,7 +4705,8 @@ static void create_autostash_internal(struct repository *r,
>   					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
>   		}
>   
> -		printf(_("Created autostash: %s\n"), buf.buf);
> +		if (!silent)
> +			printf(_("Created autostash: %s\n"), buf.buf);
>   		if (reset_head(r, &ropts) < 0)
>   			die(_("could not reset --hard"));
>   		discard_index(r->index);
> @@ -4714,12 +4718,13 @@ static void create_autostash_internal(struct repository *r,
>   
>   void create_autostash(struct repository *r, const char *path)
>   {
> -	create_autostash_internal(r, path, NULL);
> +	create_autostash_internal(r, path, NULL, NULL, false);
>   }
>   
> -void create_autostash_ref(struct repository *r, const char *refname)
> +void create_autostash_ref(struct repository *r, const char *refname,
> +			  const char *message, bool silent)
>   {
> -	create_autostash_internal(r, NULL, refname);
> +	create_autostash_internal(r, NULL, refname, message, silent);
>   }
>   
>   static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
> diff --git a/sequencer.h b/sequencer.h
> index a6fa670c7c..02d2d9db06 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -229,7 +229,8 @@ void commit_post_rewrite(struct repository *r,
>   			 const struct object_id *new_head);
>   
>   void create_autostash(struct repository *r, const char *path);
> -void create_autostash_ref(struct repository *r, const char *refname);
> +void create_autostash_ref(struct repository *r, const char *refname,
> +			  const char *message, bool silent);
>   int save_autostash(const char *path);
>   int save_autostash_ref(struct repository *r, const char *refname);
>   int apply_autostash(const char *path);

[PATCH v15 3/5] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, label_base, and stash_msg parameters to
apply_autostash_ref() and the autostash apply machinery so callers can
pass custom conflict marker labels through to
"git stash apply --label-ours/--label-theirs/--label-base", as well as
a custom stash message for "git stash store -m".

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/commit.c |  3 ++-
 builtin/merge.c  |  9 ++++++---
 sequencer.c      | 38 +++++++++++++++++++++++++++++---------
 sequencer.h      |  4 +++-
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index a3e52ac9ca..28f6174503 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1979,7 +1979,8 @@ int cmd_commit(int argc,
 				     &oid, flags);
 	}
 
-	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+			    NULL, NULL, NULL, NULL);
 
 cleanup:
 	free_commit_extra_headers(extra);
diff --git a/builtin/merge.c b/builtin/merge.c
index 3ebe190ef1..aacf8c524e 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -537,7 +537,8 @@ static void finish(struct commit *head_commit,
 	run_hooks_l(the_repository, "post-merge", squash ? "1" : "0", NULL);
 
 	if (new_head)
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 	strbuf_release(&reflog_message);
 }
 
@@ -1678,7 +1679,8 @@ int cmd_merge(int argc,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
 					  overwrite_ignore)) {
-			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					    NULL, NULL, NULL, NULL);
 			ret = 1;
 			goto done;
 		}
@@ -1851,7 +1853,8 @@ int cmd_merge(int argc,
 		else
 			fprintf(stderr, _("Merge with strategy %s failed.\n"),
 				use_strategies[0]->name);
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 		ret = 2;
 		goto done;
 	} else if (best_strategy == wt_strategy)
diff --git a/sequencer.c b/sequencer.c
index ff5258f481..7c0376d9e4 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4727,7 +4727,10 @@ void create_autostash_ref(struct repository *r, const char *refname,
 	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4738,6 +4741,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4751,7 +4760,7 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		strvec_push(&store.args, "stash");
 		strvec_push(&store.args, "store");
 		strvec_push(&store.args, "-m");
-		strvec_push(&store.args, "autostash");
+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
 		strvec_push(&store.args, "-q");
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
@@ -4782,7 +4791,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4801,11 +4811,14 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4821,7 +4834,9 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base,
+				       stash_msg);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4831,12 +4846,17 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0,
+					NULL, NULL, NULL, NULL);
 }
 
-int apply_autostash_ref(struct repository *r, const char *refname)
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base,
+					stash_msg);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 02d2d9db06..3164bd437d 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -235,7 +235,9 @@ int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
-int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

Re: [PATCH v15 3/5] sequencer: teach autostash apply to take optional conflict marker labels

[Phillip Wood]

Hi Harald

On 24/04/2026 22:10, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add label_ours, label_theirs, label_base, and stash_msg parameters to
> apply_autostash_ref() and the autostash apply machinery so callers can
> pass custom conflict marker labels through to
> "git stash apply --label-ours/--label-theirs/--label-base", as well as
> a custom stash message for "git stash store -m".

I said before that I was confused as to why we need to pass a message 
when all we're doing is saving an existing stash and the stash already 
has the message we want. As that didn't get any response I've had a more 
detailed look. The message here is used in the reflog (which is what 
"git stash list" shows) and it appears that the reason for passing a 
message when storing the stash is because "git stash store" is not smart 
enough to reuse the subject from the stash commit message by default. It 
would be nice to improve that rather than having to pass a message here. 
"git rebase --autostash" and "git merge --autostash" do not have the 
luxury of calling "git stash store" from the same process as "git stash 
create" and so to improve the autostash message for those commands we'd 
need to generate it twice which seems like an unnecessary complication.

One problem with that approach in the context of this series is that the 
stash commit message begins "On <branch we're switching from>: " rather 
than "On <branch we're switching to>: " but that means this commit is 
just hiding the fact that commit message is wrong when we create the stash.

It may well be that fixing all that turns out to be a lot of work as it 
would mean modifying do_create_stash() to allow the branch name to be 
overridden and modifying store_stash() to use the commit subject as the 
reflog message in which case we should leave that for a future series.

Thanks

Phillip

[PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> It may well be that fixing all that turns out to be a lot of work as it
> would mean modifying do_create_stash() to allow the branch name to be
> overridden and modifying store_stash() to use the commit subject as the
> reflog message in which case we should leave that for a future series.

I suspect that it is a lot of work, so maybe also better to do later.


Harald

[PATCH v15 4/5] checkout: rollback lock on early returns in merge_working_tree

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

merge_working_tree() acquires the index lock via
repo_hold_locked_index() but several early return paths exit
without calling rollback_lock_file(), leaving the lock held.
While this is currently harmless because the process exits soon
after, it becomes a problem if the function is ever called more
than once in the same process.

Add rollback_lock_file() calls to all early return paths.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/checkout.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..c80c62b37b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -857,15 +864,19 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			struct strbuf sb = STRBUF_INIT;
 			struct strbuf old_commit_shortname = STRBUF_INIT;
 
-			if (!opts->merge)
+			if (!opts->merge) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 
 			/*
 			 * Without old_branch_info->commit, the below is the same as
 			 * the two-tree unpack we already tried and failed.
 			 */
-			if (!old_branch_info->commit)
+			if (!old_branch_info->commit) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 			old_tree = repo_get_commit_tree(the_repository,
 							old_branch_info->commit);
 
@@ -897,8 +908,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			ret = reset_tree(new_tree,
 					 opts, 1,
 					 writeout_error, new_branch_info);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 			o.ancestor = old_branch_info->name;
 			if (!old_branch_info->name) {
 				strbuf_add_unique_abbrev(&old_commit_shortname,
@@ -920,8 +933,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 					 writeout_error, new_branch_info);
 			strbuf_release(&o.obuf);
 			strbuf_release(&old_commit_shortname);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 		}
 	}
 
-- 
gitgitgadget

Re: [PATCH v15 4/5] checkout: rollback lock on early returns in merge_working_tree

[Phillip Wood]

Hi Harald

On 24/04/2026 22:10, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> merge_working_tree() acquires the index lock via
> repo_hold_locked_index() but several early return paths exit
> without calling rollback_lock_file(), leaving the lock held.
> While this is currently harmless because the process exits soon
> after, it becomes a problem if the function is ever called more
> than once in the same process.
> 
> Add rollback_lock_file() calls to all early return paths.

Thanks for splitting this out, it looks good

Phillip

> 
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>   builtin/checkout.c | 29 ++++++++++++++++++++++-------
>   1 file changed, 22 insertions(+), 7 deletions(-)
> 
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index e031e61886..c80c62b37b 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   	struct tree *new_tree;
>   
>   	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
> -	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
> +	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
> +		rollback_lock_file(&lock_file);
>   		return error(_("index file corrupt"));
> +	}
>   
>   	resolve_undo_clear_index(the_repository->index);
>   	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
> @@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   	} else {
>   		new_tree = repo_get_commit_tree(the_repository,
>   						new_branch_info->commit);
> -		if (!new_tree)
> +		if (!new_tree) {
> +			rollback_lock_file(&lock_file);
>   			return error(_("unable to read tree (%s)"),
>   				     oid_to_hex(&new_branch_info->commit->object.oid));
> +		}
>   	}
>   	if (opts->discard_changes) {
>   		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
> -		if (ret)
> +		if (ret) {
> +			rollback_lock_file(&lock_file);
>   			return ret;
> +		}
>   	} else {
>   		struct tree_desc trees[2];
>   		struct tree *tree;
> @@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
>   
>   		if (unmerged_index(the_repository->index)) {
> +			rollback_lock_file(&lock_file);
>   			error(_("you need to resolve your current index first"));
>   			return 1;
>   		}
> @@ -857,15 +864,19 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   			struct strbuf sb = STRBUF_INIT;
>   			struct strbuf old_commit_shortname = STRBUF_INIT;
>   
> -			if (!opts->merge)
> +			if (!opts->merge) {
> +				rollback_lock_file(&lock_file);
>   				return 1;
> +			}
>   
>   			/*
>   			 * Without old_branch_info->commit, the below is the same as
>   			 * the two-tree unpack we already tried and failed.
>   			 */
> -			if (!old_branch_info->commit)
> +			if (!old_branch_info->commit) {
> +				rollback_lock_file(&lock_file);
>   				return 1;
> +			}
>   			old_tree = repo_get_commit_tree(the_repository,
>   							old_branch_info->commit);
>   
> @@ -897,8 +908,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   			ret = reset_tree(new_tree,
>   					 opts, 1,
>   					 writeout_error, new_branch_info);
> -			if (ret)
> +			if (ret) {
> +				rollback_lock_file(&lock_file);
>   				return ret;
> +			}
>   			o.ancestor = old_branch_info->name;
>   			if (!old_branch_info->name) {
>   				strbuf_add_unique_abbrev(&old_commit_shortname,
> @@ -920,8 +933,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   					 writeout_error, new_branch_info);
>   			strbuf_release(&o.obuf);
>   			strbuf_release(&old_commit_shortname);
> -			if (ret)
> +			if (ret) {
> +				rollback_lock_file(&lock_file);
>   				return ret;
> +			}
>   		}
>   	}
>   

[PATCH v15 5/5] checkout -m: autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", the attempted merge
of local modifications may cause conflicts with the changes made on
the other branch, which the user may not want to (or may not be able
to) resolve right now.  Because there is no easy way to recover from
this situation, we discouraged users from using "checkout -m" unless
they are certain their changes are trivial and within their ability
to resolve conflicts.

Teach the -m flow to create a temporary stash before switching and
reapply it after.  On success, the stash is silently applied and
the list of locally modified paths is shown, same as a successful
"git checkout" without "-m".

If reapplying causes conflicts, the stash is kept and the user is
told they can resolve and run "git stash drop", or run "git reset
--hard" and later "git stash pop" to recover their changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  58 ++++++------
 Documentation/git-switch.adoc   |  33 +++----
 builtin/checkout.c              | 160 ++++++++++++++------------------
 sequencer.c                     |  14 ++-
 t/t3420-rebase-autostash.sh     |  16 ++--
 t/t7201-co.sh                   |  61 +++++++++++-
 t/t7600-merge.sh                |   3 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 9 files changed, 211 insertions(+), 147 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..70dd211ee3 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,39 +577,44 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is in effect and the locally
+modified files overlap with files that need to be updated by the
+branch switch, the changes are stashed and reapplied after the
+switch.  If this process results in conflicts, a stash entry is saved
+and made available in `git stash list`:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
+Your local changes are stashed, however, applying it to carry
+forward your local changes resulted in conflicts:
 
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
+ - You can try resolving them now.  If you resolved them
+   successfully, discard the stash entry with "git stash drop".
 
+ - Alternatively you can "git reset --hard" if you do not want
+   to deal with them right now, and later "git stash pop" to
+   recover your local changes.
 ------------
-$ edit frotz
-$ git add frotz
-------------
+
+You can try resolving the conflicts now.  Edit the conflicting files
+and mark them resolved with `git add` as usual, then run `git stash
+drop` to discard the stash entry.  Alternatively, you can clear the
+working tree with `git reset --hard` and recover your local changes
+later with `git stash pop`.
 
 CONFIGURATION
 -------------
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..ee58a4d0fd 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,15 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which would carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Switched to branch 'mytopic'
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index c80c62b37b..d02183b245 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -99,6 +99,8 @@ struct checkout_opts {
 	.auto_advance = 1, \
 }
 
+#define MERGE_WORKING_TREE_UNPACK_FAILED (-2)
+
 struct branch_info {
 	char *name; /* The short name used */
 	char *path; /* The full name of a real branch */
@@ -755,7 +757,7 @@ static void setup_branch_path(struct branch_info *branch)
 
 static void init_topts(struct unpack_trees_options *topts, int merge,
 		       int show_progress, int overwrite_ignore,
-		       struct commit *old_commit)
+		       struct commit *old_commit, bool show_unpack_errors)
 {
 	memset(topts, 0, sizeof(*topts));
 	topts->head_idx = -1;
@@ -767,7 +769,7 @@ static void init_topts(struct unpack_trees_options *topts, int merge,
 	topts->initial_checkout = is_index_unborn(the_repository->index);
 	topts->update = 1;
 	topts->merge = 1;
-	topts->quiet = merge && old_commit;
+	topts->quiet = merge && old_commit && !show_unpack_errors;
 	topts->verbose_update = show_progress;
 	topts->fn = twoway_merge;
 	topts->preserve_ignored = !overwrite_ignore;
@@ -776,7 +778,8 @@ static void init_topts(struct unpack_trees_options *topts, int merge,
 static int merge_working_tree(const struct checkout_opts *opts,
 			      struct branch_info *old_branch_info,
 			      struct branch_info *new_branch_info,
-			      int *writeout_error)
+			      int *writeout_error,
+			      bool show_unpack_errors)
 {
 	int ret;
 	struct lock_file lock_file = LOCK_INIT;
@@ -827,7 +830,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 
 		/* 2-way merge to the new branch */
 		init_topts(&topts, opts->merge, opts->show_progress,
-			   opts->overwrite_ignore, old_branch_info->commit);
+			   opts->overwrite_ignore, old_branch_info->commit,
+			   show_unpack_errors);
 		init_checkout_metadata(&topts.meta, new_branch_info->refname,
 				       new_branch_info->commit ?
 				       &new_branch_info->commit->object.oid :
@@ -853,90 +857,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
+			rollback_lock_file(&lock_file);
+			return MERGE_WORKING_TREE_UNPACK_FAILED;
 		}
 	}
 
@@ -1181,6 +1103,10 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	struct strbuf autostash_msg = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1218,11 +1144,49 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name) {
+		stash_label_base = old_branch_info.name;
+	} else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
-		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
+					 &writeout_error, false);
+		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
+			strbuf_addf(&autostash_msg,
+				    "autostash while switching to '%s'",
+				    new_branch_info->name);
+			create_autostash_ref(the_repository,
+					     "CHECKOUT_AUTOSTASH_HEAD",
+					     autostash_msg.buf, true);
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
+						 &writeout_error, true);
+		}
+		if (created_autostash) {
+			if (opts->conflict_style >= 0) {
+				struct strbuf cfg = STRBUF_INIT;
+				strbuf_addf(&cfg, "merge.conflictStyle=%s",
+					    conflict_style_name(opts->conflict_style));
+				git_config_push_parameter(cfg.buf);
+				strbuf_release(&cfg);
+			}
+			apply_autostash_ref(the_repository,
+					    "CHECKOUT_AUTOSTASH_HEAD",
+					    new_branch_info->name,
+					    "local",
+					    stash_label_base,
+					    autostash_msg.buf);
+		}
 		if (ret) {
 			branch_info_release(&old_branch_info);
-			return ret;
+			strbuf_release(&old_commit_shortname);
+			strbuf_release(&autostash_msg);
+			return ret < 0 ? 1 : ret;
 		}
 	}
 
@@ -1231,8 +1195,22 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (created_autostash) {
+		discard_index(the_repository->index);
+		if (repo_read_index(the_repository) < 0)
+			die(_("index file corrupt"));
+
+		if (!opts->quiet && new_branch_info->commit) {
+			printf(_("The following paths have local changes:\n"));
+			show_local_changes(&new_branch_info->commit->object,
+					   &opts->diff_options);
+		}
+	}
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
+	strbuf_release(&autostash_msg);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index 7c0376d9e4..746f85a442 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4765,15 +4765,19 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however applying them\n"
+				  "resulted in conflicts.  You can either resolve the conflicts\n"
+				  "and then discard the stash with \"git stash drop\", or, if you\n"
+				  "do not want to resolve them now, run \"git reset --hard\" and\n"
+				  "apply the local changes later by running \"git stash pop\".\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..f0bbc476ff 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,22 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however applying them
+	resulted in conflicts.  You can either resolve the conflicts
+	and then discard the stash with "git stash drop", or, if you
+	do not want to resolve them now, run "git reset --hard" and
+	apply the local changes later by running "git stash pop".
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however applying them
+	resulted in conflicts.  You can either resolve the conflicts
+	and then discard the stash with "git stash drop", or, if you
+	do not want to resolve them now, run "git reset --hard" and
+	apply the local changes later by running "git stash pop".
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..b3293ead8d 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -102,7 +102,7 @@ test_expect_success 'checkout -m with dirty tree' '
 
 	test "$(git symbolic-ref HEAD)" = "refs/heads/side" &&
 
-	printf "M\t%s\n" one >expect.messages &&
+	printf "The following paths have local changes:\nM\t%s\n" one >expect.messages &&
 	test_cmp expect.messages messages &&
 
 	fill "M	one" "A	three" "D	two" >expect.main &&
@@ -210,6 +210,65 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m creates a recoverable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	test_grep "git stash pop" actual &&
+	test_grep "The following paths have local changes" actual &&
+	git show --format=%B --diff-merges=1 refs/stash >actual &&
+	sed /^index/d actual >actual.trimmed &&
+	cat >expect <<-EOF &&
+	On main: autostash while switching to ${SQ}side${SQ}
+
+	diff --git a/one b/one
+	--- a/one
+	+++ b/one
+	@@ -3,6 +3,3 @@
+	 3
+	 4
+	 5
+	-6
+	-7
+	-8
+	EOF
+	test_cmp expect actual.trimmed &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m which would overwrite untracked file' '
+	git checkout -f --detach main &&
+	test_commit another-file &&
+	git checkout HEAD^ &&
+	>another-file.t &&
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout -m @{-1} 2>err &&
+	test_grep "would be overwritten by checkout" err &&
+	test_grep "another-file.t" err
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..f877d9a433 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,8 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "applying them" err &&
+	test_grep "resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v15 5/5] checkout -m: autostash when switching branches

[Phillip Wood]

Hi Harald

On 24/04/2026 22:10, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> When switching branches with "git checkout -m", the attempted merge
> of local modifications may cause conflicts with the changes made on
> the other branch, which the user may not want to (or may not be able
> to) resolve right now.  Because there is no easy way to recover from
> this situation, we discouraged users from using "checkout -m" unless
> they are certain their changes are trivial and within their ability
> to resolve conflicts.
> 
> Teach the -m flow to create a temporary stash before switching and
> reapply it after.  On success, the stash is silently applied and
> the list of locally modified paths is shown, same as a successful
> "git checkout" without "-m".
> 
> If reapplying causes conflicts, the stash is kept and the user is
> told they can resolve and run "git stash drop", or run "git reset
> --hard" and later "git stash pop" to recover their changes.

This is looking good, there are just a few small issues. Hopefully the 
next iteration will be the last.

> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>   Documentation/git-checkout.adoc |  58 ++++++------
>   Documentation/git-switch.adoc   |  33 +++----
>   builtin/checkout.c              | 160 ++++++++++++++------------------
>   sequencer.c                     |  14 ++-
>   t/t3420-rebase-autostash.sh     |  16 ++--
>   t/t7201-co.sh                   |  61 +++++++++++-
>   t/t7600-merge.sh                |   3 +-
>   xdiff-interface.c               |  12 +++
>   xdiff-interface.h               |   1 +
>   9 files changed, 211 insertions(+), 147 deletions(-)
> 
> diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
> index 43ccf47cf6..70dd211ee3 100644
> --- a/Documentation/git-checkout.adoc
> +++ b/Documentation/git-checkout.adoc
> @@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
>   	are different between the current branch and the branch to
>   	which you are switching, the command refuses to switch
>   	branches in order to preserve your modifications in context.
> -	However, with this option, a three-way merge between the current
> -	branch, your working tree contents, and the new branch
> -	is done, and you will be on the new branch.
> -+
> -When a merge conflict happens, the index entries for conflicting
> -paths are left unmerged, and you need to resolve the conflicts
> -and mark the resolved paths with `git add` (or `git rm` if the merge
> -should result in deletion of the path).
> +	With this option, the conflicting local changes are
> +	automatically stashed before the switch and reapplied
> +	afterwards.  If the local changes do not overlap with the
> +	differences between branches, the switch proceeds without
> +	stashing.  If reapplying the stash results in conflicts, the
> +	entry is saved to the stash list.  Resolve the conflicts
> +	and run `git stash drop` when done, or clear the working
> +	tree (e.g. with `git reset --hard`) before running `git stash
> +	pop` later to re-apply your changes.
>   +
>   When checking out paths from the index, this option lets you recreate
>   the conflicted merge in the specified paths.  This option cannot be
>   used when checking out paths from a tree-ish.
> -+
> -When switching branches with `--merge`, staged changes may be lost.
>   
>   `--conflict=<style>`::
>   	The same as `--merge` option above, but changes the way the
> @@ -578,39 +577,44 @@ $ git checkout mytopic
>   error: You have local changes to 'frotz'; not switching branches.
>   ------------
>   
> -You can give the `-m` flag to the command, which would try a
> -three-way merge:
> +You can give the `-m` flag to the command, which would carry your local

s/would/will/ or s/would carry/carries/

> +changes to the new branch:
>   
>   ------------
>   $ git checkout -m mytopic
> -Auto-merging frotz
> +Switched to branch 'mytopic'
>   ------------
>   
> -After this three-way merge, the local modifications are _not_
> +After the switch, the local modifications are reapplied and are _not_
>   registered in your index file, 

We don't test this but we do test that "git stash apply" does not update 
the index so we should be fine.

> so `git diff` would show you what
>   changes you made since the tip of the new branch.
>   
>   === 3. Merge conflict
>   
> -When a merge conflict happens during switching branches with
> -the `-m` option, you would see something like this:
> +When the `--merge` (`-m`) option is in effect and the locally
> +modified files overlap with files  that need to be updated by the
> +branch switch,

It is the changes in the files overlapping that causes the merge 
conflict, not the files overlapping

	When the `--merge` (`-m`) option is given and the local changes
	overlap with the changes in the branch we're switching to,

> the changes are stashed and reapplied after the
> +switch.  If this process results in conflicts, a stash entry is saved

s/a/the/

> +and made available in `git stash list`:

I'd drop this line and say instead "a message is printed"

>   ------------
>   $ git checkout -m mytopic
> -Auto-merging frotz
> -ERROR: Merge conflict in frotz
> -fatal: merge program failed
> -------------
> +Your local changes are stashed, however, applying it to carry
> +forward your local changes resulted in conflicts:
>   
> -At this point, `git diff` shows the changes cleanly merged as in
> -the previous example, as well as the changes in the conflicted
> -files.  Edit and resolve the conflict and mark it resolved with
> -`git add` as usual:
> + - You can try resolving them now.  If you resolved them
> +   successfully, discard the stash entry with "git stash drop".
>   
> + - Alternatively you can "git reset --hard" if you do not want
> +   to deal with them right now, and later "git stash pop" to
> +   recover your local changes.

This needs updating to match the new conflict advice.

>   ------------
> -$ edit frotz
> -$ git add frotz
> -------------
> +
> +You can try resolving the conflicts now.  Edit the conflicting files
> +and mark them resolved with `git add` as usual, then run `git stash
> +drop` to discard the stash entry.  Alternatively, you can clear the
> +working tree with `git reset --hard` and recover your local changes
> +later with `git stash pop`.

Is this documentation, or program output?

If you've not done so already it would be well worth checking the 
generated git-checkout.html and the man page

>   CONFIGURATION
>   -------------
> diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
> index 87707e9265..ee58a4d0fd 100644
> --- a/Documentation/git-switch.adoc
> +++ b/Documentation/git-switch.adoc
> @@ -123,18 +123,19 @@ variable.
>   
>   `-m`::
>   `--merge`::
> -	If you have local modifications to one or more files that are
> -	different between the current branch and the branch to which
> -	you are switching, the command refuses to switch branches in
> -	order to preserve your modifications in context.  However,
> -	with this option, a three-way merge between the current
> -	branch, your working tree contents, and the new branch is
> -	done, and you will be on the new branch.
> -+
> -When a merge conflict happens, the index entries for conflicting
> -paths are left unmerged, and you need to resolve the conflicts
> -and mark the resolved paths with `git add` (or `git rm` if the merge
> -should result in deletion of the path).
> +	If you have local modifications to one or more files that
> +	are different between the current branch and the branch to
> +	which you are switching, the command normally refuses to
> +	switch branches in order to preserve your modifications in
> +	context.  However, with this option, the conflicting local
> +	changes are automatically stashed before the switch and
> +	reapplied afterwards.  If the local changes do not overlap
> +	with the differences between branches, the switch proceeds
> +	without stashing.  If reapplying the stash results in
> +	conflicts, the entry is saved to the stash list.  Resolve
> +	the conflicts and run `git stash drop` when done, or clear
> +	the working tree (e.g. with `git reset --hard`) before
> +	running `git stash pop` later to re-apply your changes.
>   
>   `--conflict=<style>`::
>   	The same as `--merge` option above, but changes the way the
> @@ -217,15 +218,15 @@ $ git switch mytopic
>   error: You have local changes to 'frotz'; not switching branches.
>   ------------
>   
> -You can give the `-m` flag to the command, which would try a three-way
> -merge:
> +You can give the `-m` flag to the command, which would carry your local
> +changes to the new branch:

Same comment as for git-checkout.adoc

>   ------------
>   $ git switch -m mytopic
> -Auto-merging frotz
> +Switched to branch 'mytopic'

Don't we show the modified files as well now?
>   ------------
>   
> -After this three-way merge, the local modifications are _not_
> +After the switch, the local modifications are reapplied and are _not_
>   registered in your index file, so `git diff` would show you what
>   changes you made since the tip of the new branch.
>   
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> @@ -755,7 +757,7 @@ static void setup_branch_path(struct branch_info *branch)
>   
>   static void init_topts(struct unpack_trees_options *topts, int merge,
>   		       int show_progress, int overwrite_ignore,
> -		       struct commit *old_commit)
> +		       struct commit *old_commit, bool show_unpack_errors)

As this function only sets up the flags for unpack_trees() I think we 
could call this "quiet" or "show_errors"

>   {
>   	memset(topts, 0, sizeof(*topts));
>   	topts->head_idx = -1;
> @@ -767,7 +769,7 @@ static void init_topts(struct unpack_trees_options *topts, int merge,
>   	topts->initial_checkout = is_index_unborn(the_repository->index);
>   	topts->update = 1;
>   	topts->merge = 1;
> -	topts->quiet = merge && old_commit;
> +	topts->quiet = merge && old_commit && !show_unpack_errors;

We've added a function parameter for this option but then we ignore it 
unless "merge" and "old_commit" are true which is confusing. The reason 
we used to check those was to set "quiet" automatically but we can't do 
that now, so why not just use the value the call requested?

>   	topts->verbose_update = show_progress;
>   	topts->fn = twoway_merge;
>   	topts->preserve_ignored = !overwrite_ignore;
> @@ -776,7 +778,8 @@ static void init_topts(struct unpack_trees_options *topts, int merge,
>   static int merge_working_tree(const struct checkout_opts *opts,
>   			      struct branch_info *old_branch_info,
>   			      struct branch_info *new_branch_info,
> -			      int *writeout_error)
> +			      int *writeout_error,

This is an "out" parameter, so it would make sense to keep it at the end 
of the parameter list.

> +			      bool show_unpack_errors)
>   {
> @@ -853,90 +857,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
>   		ret = unpack_trees(2, trees, &topts);
>   		clear_unpack_trees_porcelain(&topts);
>   		if (ret == -1) {
> [...]
> +			rollback_lock_file(&lock_file);
> +			return MERGE_WORKING_TREE_UNPACK_FAILED;

We now use a unique return value when unpack_trees() fails - good.

>   		}
>   	}
>   
> @@ -1181,6 +1103,10 @@ static int switch_branches(const struct checkout_opts *opts,
>   	struct object_id rev;
>   	int flag, writeout_error = 0;
>   	int do_merge = 1;
> +	int created_autostash = 0;
> +	struct strbuf old_commit_shortname = STRBUF_INIT;
> +	struct strbuf autostash_msg = STRBUF_INIT;
> +	const char *stash_label_base = NULL;
>   
>   	trace2_cmd_mode("branch");
>   
> @@ -1218,11 +1144,49 @@ static int switch_branches(const struct checkout_opts *opts,
> [...]
>   	if (do_merge) {
> -		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> +		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
> +					 &writeout_error, false);
> +		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
> +			strbuf_addf(&autostash_msg,
> +				    "autostash while switching to '%s'",

In an ideal world we'd create a message that said

	On <new branch>: autostash while switching from '<old branch>'

However I as discussed on patch 3, that would require us to be able to 
override the branch name when creating a stash as that's where the "On 
<branch>: " prefix gets added.

> +				    new_branch_info->name);
> +			create_autostash_ref(the_repository,
> +					     "CHECKOUT_AUTOSTASH_HEAD",
> +					     autostash_msg.buf, true);
> +			created_autostash = 1;
> +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
> +						 &writeout_error, true);
> +		}
> +		if (created_autostash) {
> +			if (opts->conflict_style >= 0) {
> +				struct strbuf cfg = STRBUF_INIT;
> +				strbuf_addf(&cfg, "merge.conflictStyle=%s",
> +					    conflict_style_name(opts->conflict_style));
> +				git_config_push_parameter(cfg.buf);
> +				strbuf_release(&cfg);
> +			}
> +			apply_autostash_ref(the_repository,
> +					    "CHECKOUT_AUTOSTASH_HEAD",
> +					    new_branch_info->name,
> +					    "local",
> +					    stash_label_base,
> +					    autostash_msg.buf);
> +		}

We now have a single place where we restore the stashed changes - good

> diff --git a/sequencer.c b/sequencer.c
> index 7c0376d9e4..746f85a442 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4765,15 +4765,19 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
>   		strvec_push(&store.args, stash_oid);
>   		if (run_command(&store))
>   			ret = error(_("cannot store %s"), stash_oid);
> +		else if (attempt_apply)
> +			fprintf(stderr,
> +				_("Your local changes are stashed, however applying them\n"
> +				  "resulted in conflicts.  You can either resolve the conflicts\n"
> +				  "and then discard the stash with \"git stash drop\", or, if you\n"
> +				  "do not want to resolve them now, run \"git reset --hard\" and\n"
> +				  "apply the local changes later by running \"git stash pop\".\n"));
>   		else
>   			fprintf(stderr,
> -				_("%s\n"
> +				_("Autostash exists; creating a new stash entry.\n"
>   				  "Your changes are safe in the stash.\n"
>   				  "You can run \"git stash pop\" or"
> -				  " \"git stash drop\" at any time.\n"),
> -				attempt_apply ?
> -				_("Applying autostash resulted in conflicts.") :
> -				_("Autostash exists; creating a new stash entry."));
> +				  " \"git stash drop\" at any time.\n"));
>   	}

This looks good now

> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..b3293ead8d 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -102,7 +102,7 @@ test_expect_success 'checkout -m with dirty tree' '
>   
>   	test "$(git symbolic-ref HEAD)" = "refs/heads/side" &&
>   
> -	printf "M\t%s\n" one >expect.messages &&
> +	printf "The following paths have local changes:\nM\t%s\n" one >expect.messages &&

To create a multi-line file it is clearer to use

	cat >expect.messages <<-\EOF &&
	The following paths have local changes:
	M	one
	EOF

>   	test_cmp expect.messages messages &&
>   
>   	fill "M	one" "A	three" "D	two" >expect.main &&
> @@ -210,6 +210,65 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
>   	test_cmp expect two
>   '
>   
> +test_expect_success 'checkout -m with mixed staged and unstaged changes' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 0 x y z >same &&
> +	git add same &&
> +	fill 1 2 3 4 5 6 7 >one &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep "Applied autostash" actual &&
> +	fill 0 x y z >expect &&
> +	test_cmp expect same &&
> +	fill 1 2 3 4 5 6 7 >expect &&
> +	test_cmp expect one
> +'
> +
> +test_expect_success 'checkout -m creates a recoverable stash on conflict' '
> +	git checkout -f main &&
> +	git clean -f &&
> +
> +	fill 1 2 3 4 5 >one &&
> +	test_must_fail git checkout side 2>stderr &&
> +	test_grep "Your local changes" stderr &&
> +	git checkout -m side >actual 2>&1 &&
> +	test_grep "resulted in conflicts" actual &&
> +	test_grep "git stash drop" actual &&
> +	test_grep "git stash pop" actual &&
> +	test_grep "The following paths have local changes" actual &&
> +	git show --format=%B --diff-merges=1 refs/stash >actual &&

I've realized since I suggested this that we should be checking the 
reflog message as well since that's what's shown by "git stash list" so
we need to run

   git log -p -1 --format="%gs%n%B" -g --diff-merges=1 refs/stash >actual

> +	sed /^index/d actual >actual.trimmed &&
> +	cat >expect <<-EOF &&

and add

   autostash while switching to ${SQ}side${SQ}

> +	On main: autostash while switching to ${SQ}side${SQ}
> +
> +	diff --git a/one b/one
> +	--- a/one
> +	+++ b/one
> +	@@ -3,6 +3,3 @@
> +	 3
> +	 4
> +	 5
> +	-6
> +	-7
> +	-8
> +	EOF
> +	test_cmp expect actual.trimmed &&
> +	git stash drop &&
> +	git reset --hard
> +'
> +
> +test_expect_success 'checkout -m which would overwrite untracked file' '
> +	git checkout -f --detach main &&
> +	test_commit another-file &&
> +	git checkout HEAD^ &&
> +	>another-file.t &&
> +	fill 1 2 3 4 5 >one &&
> +	test_must_fail git checkout -m @{-1} 2>err &&
> +	test_grep "would be overwritten by checkout" err &&
> +	test_grep "another-file.t" err

Why the two calls to test_grep, rather than one? Anyway I've realized 
since I suggested this test that we also need to check the message only 
appears once to prevent a regression where merge_working_tree() calls 
unpack_trees() without setting "quiet" the first time it is called. We 
can do that by writing an expect file and calling test_cmp(), or by 
using "test_line_count = 1 err"

Hopefully the next re-roll with be the final one

Thanks

Phillip

> +'
> +
>   test_expect_success 'switch to another branch while carrying a deletion' '
>   	git checkout -f main &&
>   	git reset --hard &&
> diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
> index 9838094b66..f877d9a433 100755
> --- a/t/t7600-merge.sh
> +++ b/t/t7600-merge.sh
> @@ -914,7 +914,8 @@ test_expect_success 'merge with conflicted --autostash changes' '
>   	git diff >expect &&
>   	test_when_finished "test_might_fail git stash drop" &&
>   	git merge --autostash c3 2>err &&
> -	test_grep "Applying autostash resulted in conflicts." err &&
> +	test_grep "applying them" err &&
> +	test_grep "resulted in conflicts" err &&
>   	git show HEAD:file >merge-result &&
>   	test_cmp result.1-9 merge-result &&
>   	git stash show -p >actual &&
> diff --git a/xdiff-interface.c b/xdiff-interface.c
> index f043330f2a..5ee2b96d0a 100644
> --- a/xdiff-interface.c
> +++ b/xdiff-interface.c
> @@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
>   		return -1;
>   }
>   
> +const char *conflict_style_name(int style)
> +{
> +	switch (style) {
> +	case XDL_MERGE_DIFF3:
> +		return "diff3";
> +	case XDL_MERGE_ZEALOUS_DIFF3:
> +		return "zdiff3";
> +	default:
> +		return "merge";
> +	}
> +}
> +
>   int git_xmerge_style = -1;
>   
>   int git_xmerge_config(const char *var, const char *value,
> diff --git a/xdiff-interface.h b/xdiff-interface.h
> index fbc4ceec40..ce54e1c0e0 100644
> --- a/xdiff-interface.h
> +++ b/xdiff-interface.h
> @@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
>   void xdiff_clear_find_func(xdemitconf_t *xecfg);
>   struct config_context;
>   int parse_conflict_style_name(const char *value);
> +const char *conflict_style_name(int style);
>   int git_xmerge_config(const char *var, const char *value,
>   		      const struct config_context *ctx, void *cb);
>   extern int git_xmerge_style;

[PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> This is looking good, there are just a few small issues. Hopefully the
> next iteration will be the last.

Thanks for the encouragement! 💪🏻

> s/would/will/

👍

> It is the changes in the files overlapping that causes the merge
> conflict, not the files overlapping
> 
>         When the `--merge` (`-m`) option is given and the local changes
>         overlap with the changes in the branch we're switching to,

👍

> I'd drop this line and say instead "a message is printed"

👍

> This needs updating to match the new conflict advice.

👍

> If you've not done so already it would be well worth checking the
> generated git-checkout.html and the man page

Good catch, I generated it now and yes it didn't look correct. I dropped
that last section now.

> Don't we show the modified files as well now?

Good catch, very good idea to actually generate the man html file and
check.

> As this function only sets up the flags for unpack_trees() I think we
> could call this "quiet" or "show_errors"

Good point!

> We've added a function parameter for this option but then we ignore it
> unless "merge" and "old_commit" are true which is confusing. The reason
> we used to check those was to set "quiet" automatically but we can't do
> that now, so why not just use the value the call requested?

Good point! I attempted to change this, hopefully it doesn't break anything!

> This is an "out" parameter, so it would make sense to keep it at the end
> of the parameter list.

👍

> To create a multi-line file it is clearer to use
> 
>         cat >expect.messages <<-\EOF &&
>         The following paths have local changes:
>         M       one
>         EOF

👍

> I've realized since I suggested this that we should be checking the
> reflog message as well since that's what's shown by "git stash list" so
> we need to run
> 
>    git log -p -1 --format="%gs%n%B" -g --diff-merges=1 refs/stash >actual
> 
> > +     sed /^index/d actual >actual.trimmed &&
> > +     cat >expect <<-EOF &&
> 
> and add
> 
> 
>    autostash while switching to ${SQ}side${SQ}

Make sense!

> Why the two calls to test_grep, rather than one? Anyway I've realized
> since I suggested this test that we also need to check the message only
> appears once to prevent a regression where merge_working_tree() calls
> unpack_trees() without setting "quiet" the first time it is called. We
> can do that by writing an expect file and calling test_cmp(), or by
> using "test_line_count = 1 err"

Excellent point. I went with test_cmp since it's multi-line output and
"test_line_count = 1" seemed to not work then.


Harald

Re: [PATCH v15 0/5] checkout: 'autostash' for branch switching

[Phillip Wood]

Hi Harald

On 24/04/2026 22:10, Harald Nordgren via GitGitGadget wrote:
>   * When the initial merge fails, the caller now knows for sure it was a
>     conflict (not some unrelated error) before kicking off the autostash.
> 
>   * If the second attempt also fails, the user now actually sees why.
>     Previously errors like "would be overwritten by checkout" were being
>     swallowed.
> 
>   * The stash is reapplied right after the second attempt, so it won't get
>     left behind if something else goes wrong later in the checkout.
> 
>   * A couple of clean-up steps only run when we actually stashed, so regular
>     checkouts aren't paying for work they don't need.
> 
>   * Added a small header "The following paths have local changes:" before the
>     list of changed files, so it doesn't look like part of the conflict
>     advice above it.
> 
>   * Reworded the conflict advice into a single paragraph. Feels less shouty
>     and doesn't say "local changes" three times.
> 
>   * Trimmed and consolidated tests in t7201. A bunch of the old ones couldn't
>     actually fail, or were really testing other things; the conflict-path
>     tests are now a single test that checks the stash entry directly.

Thanks for the summary, that all looks good. I've left some comments on 
Patches 1 and 3 but they can be future work and don't need to hold this 
series up. There are a few small issues that need addressing on Patch 5 
but hopefully the next iteration will be the last.

Thanks

Phillip

> Harald Nordgren (5):
>    stash: add --label-ours, --label-theirs, --label-base for apply
>    sequencer: allow create_autostash to run silently
>    sequencer: teach autostash apply to take optional conflict marker
>      labels
>    checkout: rollback lock on early returns in merge_working_tree
>    checkout -m: autostash when switching branches
> 
>   Documentation/git-checkout.adoc |  58 +++++------
>   Documentation/git-stash.adoc    |  11 ++-
>   Documentation/git-switch.adoc   |  33 +++----
>   builtin/checkout.c              | 165 +++++++++++++++-----------------
>   builtin/commit.c                |   3 +-
>   builtin/merge.c                 |  15 ++-
>   builtin/stash.c                 |  28 ++++--
>   sequencer.c                     |  69 +++++++++----
>   sequencer.h                     |   7 +-
>   t/t3420-rebase-autostash.sh     |  16 ++--
>   t/t3903-stash.sh                |  24 +++++
>   t/t7201-co.sh                   |  61 +++++++++++-
>   t/t7600-merge.sh                |   3 +-
>   xdiff-interface.c               |  12 +++
>   xdiff-interface.h               |   1 +
>   xdiff/xmerge.c                  |   6 +-
>   16 files changed, 335 insertions(+), 177 deletions(-)
> 
> 
> base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v15
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v15
> Pull-Request: https://github.com/git/git/pull/2234
> 
> Range-diff vs v14:
> 
>   1:  e18c25599a = 1:  aba8e6a9dc stash: add --label-ours, --label-theirs, --label-base for apply
>   2:  ce29b10264 = 2:  89e0bfa803 sequencer: allow create_autostash to run silently
>   3:  73051d1762 = 3:  a428ce7328 sequencer: teach autostash apply to take optional conflict marker labels
>   4:  191058d8e3 = 4:  f358424085 checkout: rollback lock on early returns in merge_working_tree
>   5:  86f33df1eb ! 5:  96b14db827 checkout -m: autostash when switching branches
>       @@ builtin/checkout.c
>         #include "setup.h"
>         #include "submodule.h"
>         #include "symlinks.h"
>       +@@ builtin/checkout.c: struct checkout_opts {
>       + 	.auto_advance = 1, \
>       + }
>       +
>       ++#define MERGE_WORKING_TREE_UNPACK_FAILED (-2)
>       ++
>       + struct branch_info {
>       + 	char *name; /* The short name used */
>       + 	char *path; /* The full name of a real branch */
>       +@@ builtin/checkout.c: static void setup_branch_path(struct branch_info *branch)
>       +
>       + static void init_topts(struct unpack_trees_options *topts, int merge,
>       + 		       int show_progress, int overwrite_ignore,
>       +-		       struct commit *old_commit)
>       ++		       struct commit *old_commit, bool show_unpack_errors)
>       + {
>       + 	memset(topts, 0, sizeof(*topts));
>       + 	topts->head_idx = -1;
>       +@@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, int merge,
>       + 	topts->initial_checkout = is_index_unborn(the_repository->index);
>       + 	topts->update = 1;
>       + 	topts->merge = 1;
>       +-	topts->quiet = merge && old_commit;
>       ++	topts->quiet = merge && old_commit && !show_unpack_errors;
>       + 	topts->verbose_update = show_progress;
>       + 	topts->fn = twoway_merge;
>       + 	topts->preserve_ignored = !overwrite_ignore;
>       +@@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, int merge,
>       + static int merge_working_tree(const struct checkout_opts *opts,
>       + 			      struct branch_info *old_branch_info,
>       + 			      struct branch_info *new_branch_info,
>       +-			      int *writeout_error)
>       ++			      int *writeout_error,
>       ++			      bool show_unpack_errors)
>       + {
>       + 	int ret;
>       + 	struct lock_file lock_file = LOCK_INIT;
>       +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
>       +
>       + 		/* 2-way merge to the new branch */
>       + 		init_topts(&topts, opts->merge, opts->show_progress,
>       +-			   opts->overwrite_ignore, old_branch_info->commit);
>       ++			   opts->overwrite_ignore, old_branch_info->commit,
>       ++			   show_unpack_errors);
>       + 		init_checkout_metadata(&topts.meta, new_branch_info->refname,
>       + 				       new_branch_info->commit ?
>       + 				       &new_branch_info->commit->object.oid :
>        @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
>         		ret = unpack_trees(2, trees, &topts);
>         		clear_unpack_trees_porcelain(&topts);
>       @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op
>        -				return ret;
>        -			}
>        +			rollback_lock_file(&lock_file);
>       -+			return ret;
>       ++			return MERGE_WORKING_TREE_UNPACK_FAILED;
>         		}
>         	}
>         
>       @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>         			do_merge = 0;
>         	}
>         
>       -+	if (old_branch_info.name)
>       ++	if (old_branch_info.name) {
>        +		stash_label_base = old_branch_info.name;
>       -+	else if (old_branch_info.commit) {
>       ++	} else if (old_branch_info.commit) {
>        +		strbuf_add_unique_abbrev(&old_commit_shortname,
>        +					 &old_branch_info.commit->object.oid,
>        +					 DEFAULT_ABBREV);
>       @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>        +	}
>        +
>         	if (do_merge) {
>       - 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>       -+		if (ret == -1 && opts->merge) {
>       +-		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>       ++		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
>       ++					 &writeout_error, false);
>       ++		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
>        +			strbuf_addf(&autostash_msg,
>        +				    "autostash while switching to '%s'",
>        +				    new_branch_info->name);
>       @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>        +					     "CHECKOUT_AUTOSTASH_HEAD",
>        +					     autostash_msg.buf, true);
>        +			created_autostash = 1;
>       -+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>       ++			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
>       ++						 &writeout_error, true);
>       ++		}
>       ++		if (created_autostash) {
>       ++			if (opts->conflict_style >= 0) {
>       ++				struct strbuf cfg = STRBUF_INIT;
>       ++				strbuf_addf(&cfg, "merge.conflictStyle=%s",
>       ++					    conflict_style_name(opts->conflict_style));
>       ++				git_config_push_parameter(cfg.buf);
>       ++				strbuf_release(&cfg);
>       ++			}
>       ++			apply_autostash_ref(the_repository,
>       ++					    "CHECKOUT_AUTOSTASH_HEAD",
>       ++					    new_branch_info->name,
>       ++					    "local",
>       ++					    stash_label_base,
>       ++					    autostash_msg.buf);
>        +		}
>         		if (ret) {
>       -+			if (created_autostash)
>       -+				apply_autostash_ref(the_repository,
>       -+						    "CHECKOUT_AUTOSTASH_HEAD",
>       -+						    new_branch_info->name,
>       -+						    "local",
>       -+						    stash_label_base,
>       -+						    autostash_msg.buf);
>         			branch_info_release(&old_branch_info);
>        -			return ret;
>        +			strbuf_release(&old_commit_shortname);
>       @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>         
>         	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
>         
>       -+	if (opts->conflict_style >= 0) {
>       -+		struct strbuf cfg = STRBUF_INIT;
>       -+		strbuf_addf(&cfg, "merge.conflictStyle=%s",
>       -+			    conflict_style_name(opts->conflict_style));
>       -+		git_config_push_parameter(cfg.buf);
>       -+		strbuf_release(&cfg);
>       ++	if (created_autostash) {
>       ++		discard_index(the_repository->index);
>       ++		if (repo_read_index(the_repository) < 0)
>       ++			die(_("index file corrupt"));
>       ++
>       ++		if (!opts->quiet && new_branch_info->commit) {
>       ++			printf(_("The following paths have local changes:\n"));
>       ++			show_local_changes(&new_branch_info->commit->object,
>       ++					   &opts->diff_options);
>       ++		}
>        +	}
>       -+	apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH_HEAD",
>       -+			    new_branch_info->name, "local",
>       -+			    stash_label_base,
>       -+			    autostash_msg.buf);
>       -+
>       -+	discard_index(the_repository->index);
>       -+	if (repo_read_index(the_repository) < 0)
>       -+		die(_("index file corrupt"));
>       -+
>       -+	if (created_autostash && !opts->quiet && new_branch_info->commit)
>       -+		show_local_changes(&new_branch_info->commit->object,
>       -+				   &opts->diff_options);
>        +
>         	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
>         	branch_info_release(&old_branch_info);
>       @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
>         			ret = error(_("cannot store %s"), stash_oid);
>        +		else if (attempt_apply)
>        +			fprintf(stderr,
>       -+				_("Your local changes are stashed, however, applying it to carry\n"
>       -+				  "forward your local changes resulted in conflicts:\n"
>       -+				  "\n"
>       -+				  " - You can try resolving them now.  If you resolved them\n"
>       -+				  "   successfully, discard the stash entry with \"git stash drop\".\n"
>       -+				  "\n"
>       -+				  " - Alternatively you can \"git reset --hard\" if you do not want\n"
>       -+				  "   to deal with them right now, and later \"git stash pop\" to\n"
>       -+				  "   recover your local changes.\n"));
>       ++				_("Your local changes are stashed, however applying them\n"
>       ++				  "resulted in conflicts.  You can either resolve the conflicts\n"
>       ++				  "and then discard the stash with \"git stash drop\", or, if you\n"
>       ++				  "do not want to resolve them now, run \"git reset --hard\" and\n"
>       ++				  "apply the local changes later by running \"git stash pop\".\n"));
>         		else
>         			fprintf(stderr,
>        -				_("%s\n"
>       @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {
>        -	Applying autostash resulted in conflicts.
>        -	Your changes are safe in the stash.
>        -	You can run "git stash pop" or "git stash drop" at any time.
>       -+	Your local changes are stashed, however, applying it to carry
>       -+	forward your local changes resulted in conflicts:
>       -+
>       -+	 - You can try resolving them now.  If you resolved them
>       -+	   successfully, discard the stash entry with "git stash drop".
>       -+
>       -+	 - Alternatively you can "git reset --hard" if you do not want
>       -+	   to deal with them right now, and later "git stash pop" to
>       -+	   recover your local changes.
>       ++	Your local changes are stashed, however applying them
>       ++	resulted in conflicts.  You can either resolve the conflicts
>       ++	and then discard the stash with "git stash drop", or, if you
>       ++	do not want to resolve them now, run "git reset --hard" and
>       ++	apply the local changes later by running "git stash pop".
>         	EOF
>         }
>         
>       @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () {
>        -	Applying autostash resulted in conflicts.
>        -	Your changes are safe in the stash.
>        -	You can run "git stash pop" or "git stash drop" at any time.
>       -+	Your local changes are stashed, however, applying it to carry
>       -+	forward your local changes resulted in conflicts:
>       -+
>       -+	 - You can try resolving them now.  If you resolved them
>       -+	   successfully, discard the stash entry with "git stash drop".
>       -+
>       -+	 - Alternatively you can "git reset --hard" if you do not want
>       -+	   to deal with them right now, and later "git stash pop" to
>       -+	   recover your local changes.
>       ++	Your local changes are stashed, however applying them
>       ++	resulted in conflicts.  You can either resolve the conflicts
>       ++	and then discard the stash with "git stash drop", or, if you
>       ++	do not want to resolve them now, run "git reset --hard" and
>       ++	apply the local changes later by running "git stash pop".
>         	Successfully rebased and updated refs/heads/rebased-feature-branch.
>         	EOF
>         }
>        
>         ## t/t7201-co.sh ##
>       +@@ t/t7201-co.sh: test_expect_success 'checkout -m with dirty tree' '
>       +
>       + 	test "$(git symbolic-ref HEAD)" = "refs/heads/side" &&
>       +
>       +-	printf "M\t%s\n" one >expect.messages &&
>       ++	printf "The following paths have local changes:\nM\t%s\n" one >expect.messages &&
>       + 	test_cmp expect.messages messages &&
>       +
>       + 	fill "M	one" "A	three" "D	two" >expect.main &&
>        @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
>         	test_cmp expect two
>         '
>         
>       -+test_expect_success 'checkout --merge --conflict=zdiff3 <branch>' '
>       -+	git checkout -f main &&
>       -+	git reset --hard &&
>       -+	git clean -f &&
>       -+
>       -+	fill a b X d e >two &&
>       -+	git checkout --merge --conflict=zdiff3 simple &&
>       -+
>       -+	cat <<-EOF >expect &&
>       -+	a
>       -+	<<<<<<< simple
>       -+	c
>       -+	||||||| main
>       -+	b
>       -+	c
>       -+	d
>       -+	=======
>       -+	b
>       -+	X
>       -+	d
>       -+	>>>>>>> local
>       -+	e
>       -+	EOF
>       -+	test_cmp expect two
>       -+'
>       -+
>       -+test_expect_success 'checkout -m respects merge.conflictStyle config' '
>       -+	git checkout -f main &&
>       -+	git reset --hard &&
>       -+	git clean -f &&
>       -+
>       -+	test_config merge.conflictStyle diff3 &&
>       -+	fill b d >two &&
>       -+	git checkout -m simple &&
>       -+
>       -+	cat <<-EOF >expect &&
>       -+	<<<<<<< simple
>       -+	a
>       -+	c
>       -+	e
>       -+	||||||| main
>       -+	a
>       -+	b
>       -+	c
>       -+	d
>       -+	e
>       -+	=======
>       -+	b
>       -+	d
>       -+	>>>>>>> local
>       -+	EOF
>       -+	test_cmp expect two
>       -+'
>       -+
>       -+test_expect_success 'checkout -m skips stash when no conflict' '
>       -+	git checkout -f main &&
>       -+	git clean -f &&
>       -+
>       -+	fill 0 x y z >same &&
>       -+	git stash list >stash-before &&
>       -+	git checkout -m side >actual 2>&1 &&
>       -+	test_grep ! "Created autostash" actual &&
>       -+	git stash list >stash-after &&
>       -+	test_cmp stash-before stash-after &&
>       -+	fill 0 x y z >expect &&
>       -+	test_cmp expect same
>       -+'
>       -+
>       -+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' '
>       -+	git checkout -f main &&
>       -+	git clean -f &&
>       -+
>       -+	fill 0 x y z >same &&
>       -+	git add same &&
>       -+	git checkout -m side >actual 2>&1 &&
>       -+	test_grep ! "Created autostash" actual &&
>       -+	fill 0 x y z >expect &&
>       -+	test_cmp expect same
>       -+'
>       -+
>       -+test_expect_success 'checkout -m stashes and applies on conflicting changes' '
>       -+	git checkout -f main &&
>       -+	git clean -f &&
>       -+
>       -+	fill 1 2 3 4 5 6 7 >one &&
>       -+	git checkout -m side >actual 2>&1 &&
>       -+	test_grep ! "Created autostash" actual &&
>       -+	test_grep "Applied autostash" actual &&
>       -+	fill 1 2 3 4 5 6 7 >expect &&
>       -+	test_cmp expect one
>       -+'
>       -+
>        +test_expect_success 'checkout -m with mixed staged and unstaged changes' '
>        +	git checkout -f main &&
>        +	git clean -f &&
>       @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
>        +	git add same &&
>        +	fill 1 2 3 4 5 6 7 >one &&
>        +	git checkout -m side >actual 2>&1 &&
>       -+	test_grep ! "Created autostash" actual &&
>        +	test_grep "Applied autostash" actual &&
>        +	fill 0 x y z >expect &&
>        +	test_cmp expect same &&
>       @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
>        +	test_cmp expect one
>        +'
>        +
>       -+test_expect_success 'checkout -m stashes on truly conflicting changes' '
>       ++test_expect_success 'checkout -m creates a recoverable stash on conflict' '
>        +	git checkout -f main &&
>        +	git clean -f &&
>        +
>       @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
>        +	test_must_fail git checkout side 2>stderr &&
>        +	test_grep "Your local changes" stderr &&
>        +	git checkout -m side >actual 2>&1 &&
>       -+	test_grep ! "Created autostash" actual &&
>        +	test_grep "resulted in conflicts" actual &&
>        +	test_grep "git stash drop" actual &&
>       ++	test_grep "git stash pop" actual &&
>       ++	test_grep "The following paths have local changes" actual &&
>       ++	git show --format=%B --diff-merges=1 refs/stash >actual &&
>       ++	sed /^index/d actual >actual.trimmed &&
>       ++	cat >expect <<-EOF &&
>       ++	On main: autostash while switching to ${SQ}side${SQ}
>       ++
>       ++	diff --git a/one b/one
>       ++	--- a/one
>       ++	+++ b/one
>       ++	@@ -3,6 +3,3 @@
>       ++	 3
>       ++	 4
>       ++	 5
>       ++	-6
>       ++	-7
>       ++	-8
>       ++	EOF
>       ++	test_cmp expect actual.trimmed &&
>        +	git stash drop &&
>        +	git reset --hard
>        +'
>        +
>       -+test_expect_success 'checkout -m produces usable stash on conflict' '
>       -+	git checkout -f main &&
>       -+	git clean -f &&
>       -+
>       ++test_expect_success 'checkout -m which would overwrite untracked file' '
>       ++	git checkout -f --detach main &&
>       ++	test_commit another-file &&
>       ++	git checkout HEAD^ &&
>       ++	>another-file.t &&
>        +	fill 1 2 3 4 5 >one &&
>       -+	git checkout -m side >actual 2>&1 &&
>       -+	test_grep "recover your local changes" actual &&
>       -+	git checkout -f main &&
>       -+	git stash pop &&
>       -+	fill 1 2 3 4 5 >expect &&
>       -+	test_cmp expect one
>       -+'
>       -+
>       -+test_expect_success 'checkout -m autostash message includes target branch' '
>       -+	git checkout -f main &&
>       -+	git clean -f &&
>       -+
>       -+	fill 1 2 3 4 5 >one &&
>       -+	git checkout -m side >actual 2>&1 &&
>       -+	git stash list >stash-list &&
>       -+	test_grep "autostash while switching to .side." stash-list &&
>       -+	git stash drop &&
>       -+	git checkout -f main &&
>       -+	git reset --hard
>       -+'
>       -+
>       -+test_expect_success 'checkout -m stashes on staged conflicting changes' '
>       -+	git checkout -f main &&
>       -+	git clean -f &&
>       -+
>       -+	fill 1 2 3 4 5 >one &&
>       -+	git add one &&
>       -+	git checkout -m side >actual 2>&1 &&
>       -+	test_grep ! "Created autostash" actual &&
>       -+	test_grep "resulted in conflicts" actual &&
>       -+	test_grep "git stash drop" actual &&
>       -+	git stash drop &&
>       -+	git reset --hard
>       -+'
>       -+
>       -+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' '
>       -+	git checkout -f main &&
>       -+	git reset --hard &&
>       -+	git clean -f &&
>       -+
>       -+	git checkout -b nonoverlap_base &&
>       -+	fill a b c d >file &&
>       -+	git add file &&
>       -+	git commit -m "add file" &&
>       -+
>       -+	git checkout -b nonoverlap_child &&
>       -+	fill a b c INSERTED d >file &&
>       -+	git commit -a -m "insert line near end of file" &&
>       -+
>       -+	fill DIRTY a b c INSERTED d >file &&
>       -+
>       -+	git stash list >stash-before &&
>       -+	git checkout -m nonoverlap_base 2>stderr &&
>       -+	test_grep "Applied autostash" stderr &&
>       -+	test_grep ! "resulted in conflicts" stderr &&
>       -+
>       -+	git stash list >stash-after &&
>       -+	test_cmp stash-before stash-after &&
>       -+
>       -+	fill DIRTY a b c d >expect &&
>       -+	test_cmp expect file &&
>       -+
>       -+	git checkout -f main &&
>       -+	git branch -D nonoverlap_base &&
>       -+	git branch -D nonoverlap_child
>       -+'
>       -+
>       -+test_expect_success 'checkout -m -b skips stash with dirty tree' '
>       -+	git checkout -f main &&
>       -+	git clean -f &&
>       -+
>       -+	fill 0 x y z >same &&
>       -+	git checkout -m -b newbranch >actual 2>&1 &&
>       -+	test_grep ! "Created autostash" actual &&
>       -+	fill 0 x y z >expect &&
>       -+	test_cmp expect same &&
>       -+	git checkout main &&
>       -+	git branch -D newbranch
>       ++	test_must_fail git checkout -m @{-1} 2>err &&
>       ++	test_grep "would be overwritten by checkout" err &&
>       ++	test_grep "another-file.t" err
>        +'
>        +
>         test_expect_success 'switch to another branch while carrying a deletion' '
>       @@ t/t7600-merge.sh: test_expect_success 'merge with conflicted --autostash changes
>         	test_when_finished "test_might_fail git stash drop" &&
>         	git merge --autostash c3 2>err &&
>        -	test_grep "Applying autostash resulted in conflicts." err &&
>       -+	test_grep "your local changes resulted in conflicts" err &&
>       ++	test_grep "applying them" err &&
>       ++	test_grep "resulted in conflicts" err &&
>         	git show HEAD:file >merge-result &&
>         	test_cmp result.1-9 merge-result &&
>         	git stash show -p >actual &&
> 

[PATCH v16 0/5] checkout: 'autostash' for branch switching

[Harald Nordgren via GitGitGadget]

 * Updated the git checkout and git switch docs to show the actual output
   when using -m to carry local changes across a branch switch, and changed
   "would carry" to "will carry".
 * Rewrote the merge-conflict example in both docs to match the new, more
   concise message printed on autostash conflicts.
 * Replaced the show_unpack_errors flag and old_commit parameter in
   merge_working_tree()/init_topts() with a plain quiet boolean, so the
   caller decides directly whether to suppress unpack errors.
 * Tightened the 'checkout -m with dirty tree' test by replacing a printf
   with a heredoc.
 * Made the 'checkout -m creates a recoverable stash on conflict' test also
   assert the reflog subject of the new stash entry.
 * Replaced two test_grep calls in the 'checkout -m which would overwrite
   untracked file' test with a single test_cmp, which also catches a
   regression where the "would be overwritten" message could end up printed
   twice.

Harald Nordgren (5):
  stash: add --label-ours, --label-theirs, --label-base for apply
  sequencer: allow create_autostash to run silently
  sequencer: teach autostash apply to take optional conflict marker
    labels
  checkout: rollback lock on early returns in merge_working_tree
  checkout -m: autostash when switching branches

 Documentation/git-checkout.adoc |  55 +++++------
 Documentation/git-stash.adoc    |  11 ++-
 Documentation/git-switch.adoc   |  36 ++++---
 builtin/checkout.c              | 166 +++++++++++++++-----------------
 builtin/commit.c                |   3 +-
 builtin/merge.c                 |  15 ++-
 builtin/stash.c                 |  28 ++++--
 sequencer.c                     |  69 +++++++++----
 sequencer.h                     |   7 +-
 t/t3420-rebase-autostash.sh     |  16 +--
 t/t3903-stash.sh                |  24 +++++
 t/t7201-co.sh                   |  71 +++++++++++++-
 t/t7600-merge.sh                |   3 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 xdiff/xmerge.c                  |   6 +-
 16 files changed, 343 insertions(+), 180 deletions(-)


base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v16
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v16
Pull-Request: https://github.com/git/git/pull/2234

Range-diff vs v15:

 1:  aba8e6a9dc = 1:  aba8e6a9dc stash: add --label-ours, --label-theirs, --label-base for apply
 2:  89e0bfa803 = 2:  89e0bfa803 sequencer: allow create_autostash to run silently
 3:  a428ce7328 = 3:  a428ce7328 sequencer: teach autostash apply to take optional conflict marker labels
 4:  f358424085 = 4:  f358424085 checkout: rollback lock on early returns in merge_working_tree
 5:  96b14db827 ! 5:  07d25fda91 checkout -m: autostash when switching branches
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
       
      -You can give the `-m` flag to the command, which would try a
      -three-way merge:
     -+You can give the `-m` flag to the command, which would carry your local
     ++You can give the `-m` flag to the command, which will carry your local
      +changes to the new branch:
       
       ------------
       $ git checkout -m mytopic
      -Auto-merging frotz
     ++Applied autostash.
      +Switched to branch 'mytopic'
     ++The following paths have local changes:
     ++M	frotz
       ------------
       
      -After this three-way merge, the local modifications are _not_
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
       
      -When a merge conflict happens during switching branches with
      -the `-m` option, you would see something like this:
     -+When the `--merge` (`-m`) option is in effect and the locally
     -+modified files overlap with files that need to be updated by the
     -+branch switch, the changes are stashed and reapplied after the
     -+switch.  If this process results in conflicts, a stash entry is saved
     -+and made available in `git stash list`:
     ++When the `--merge` (`-m`) option is given and the local changes
     ++overlap with the changes in the branch we're switching to, the
     ++changes are stashed and reapplied after the switch.  If this
     ++process results in conflicts, the stash entry is saved and a
     ++message is printed:
       
       ------------
       $ git checkout -m mytopic
     @@ Documentation/git-checkout.adoc: $ git checkout mytopic
      -ERROR: Merge conflict in frotz
      -fatal: merge program failed
      -------------
     -+Your local changes are stashed, however, applying it to carry
     -+forward your local changes resulted in conflicts:
     - 
     +-
      -At this point, `git diff` shows the changes cleanly merged as in
      -the previous example, as well as the changes in the conflicted
      -files.  Edit and resolve the conflict and mark it resolved with
      -`git add` as usual:
     -+ - You can try resolving them now.  If you resolved them
     -+   successfully, discard the stash entry with "git stash drop".
     - 
     -+ - Alternatively you can "git reset --hard" if you do not want
     -+   to deal with them right now, and later "git stash pop" to
     -+   recover your local changes.
     - ------------
     +-
     +-------------
      -$ edit frotz
      -$ git add frotz
     --------------
     -+
     -+You can try resolving the conflicts now.  Edit the conflicting files
     -+and mark them resolved with `git add` as usual, then run `git stash
     -+drop` to discard the stash entry.  Alternatively, you can clear the
     -+working tree with `git reset --hard` and recover your local changes
     -+later with `git stash pop`.
     ++Your local changes are stashed, however applying them
     ++resulted in conflicts.  You can either resolve the conflicts
     ++and then discard the stash with "git stash drop", or, if you
     ++do not want to resolve them now, run "git reset --hard" and
     ++apply the local changes later by running "git stash pop".
     + ------------
       
       CONFIGURATION
     - -------------
      
       ## Documentation/git-switch.adoc ##
      @@ Documentation/git-switch.adoc: variable.
     @@ Documentation/git-switch.adoc: $ git switch mytopic
       
      -You can give the `-m` flag to the command, which would try a three-way
      -merge:
     -+You can give the `-m` flag to the command, which would carry your local
     ++You can give the `-m` flag to the command, which will carry your local
      +changes to the new branch:
       
       ------------
       $ git switch -m mytopic
      -Auto-merging frotz
     ++Applied autostash.
      +Switched to branch 'mytopic'
     ++The following paths have local changes:
     ++M	frotz
       ------------
       
      -After this three-way merge, the local modifications are _not_
     @@ builtin/checkout.c: struct checkout_opts {
       	char *name; /* The short name used */
       	char *path; /* The full name of a real branch */
      @@ builtin/checkout.c: static void setup_branch_path(struct branch_info *branch)
     + 	branch->path = strbuf_detach(&buf, NULL);
     + }
       
     - static void init_topts(struct unpack_trees_options *topts, int merge,
     +-static void init_topts(struct unpack_trees_options *topts, int merge,
     ++static void init_topts(struct unpack_trees_options *topts,
       		       int show_progress, int overwrite_ignore,
      -		       struct commit *old_commit)
     -+		       struct commit *old_commit, bool show_unpack_errors)
     ++		       bool quiet)
       {
       	memset(topts, 0, sizeof(*topts));
       	topts->head_idx = -1;
     @@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, i
       	topts->update = 1;
       	topts->merge = 1;
      -	topts->quiet = merge && old_commit;
     -+	topts->quiet = merge && old_commit && !show_unpack_errors;
     ++	topts->quiet = quiet;
       	topts->verbose_update = show_progress;
       	topts->fn = twoway_merge;
       	topts->preserve_ignored = !overwrite_ignore;
     @@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, i
       static int merge_working_tree(const struct checkout_opts *opts,
       			      struct branch_info *old_branch_info,
       			      struct branch_info *new_branch_info,
     --			      int *writeout_error)
     -+			      int *writeout_error,
     -+			      bool show_unpack_errors)
     ++			      bool quiet,
     + 			      int *writeout_error)
       {
       	int ret;
     - 	struct lock_file lock_file = LOCK_INIT;
      @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
     + 		}
       
       		/* 2-way merge to the new branch */
     - 		init_topts(&topts, opts->merge, opts->show_progress,
     +-		init_topts(&topts, opts->merge, opts->show_progress,
      -			   opts->overwrite_ignore, old_branch_info->commit);
     -+			   opts->overwrite_ignore, old_branch_info->commit,
     -+			   show_unpack_errors);
     ++		init_topts(&topts, opts->show_progress,
     ++			   opts->overwrite_ignore, quiet);
       		init_checkout_metadata(&topts.meta, new_branch_info->refname,
       				       new_branch_info->commit ?
       				       &new_branch_info->commit->object.oid :
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
       	if (do_merge) {
      -		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
      +		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
     -+					 &writeout_error, false);
     ++					 opts->merge, &writeout_error);
      +		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
      +			strbuf_addf(&autostash_msg,
      +				    "autostash while switching to '%s'",
     @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
      +					     autostash_msg.buf, true);
      +			created_autostash = 1;
      +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
     -+						 &writeout_error, true);
     ++						 false, &writeout_error);
      +		}
      +		if (created_autostash) {
      +			if (opts->conflict_style >= 0) {
     @@ t/t7201-co.sh: test_expect_success 'checkout -m with dirty tree' '
       	test "$(git symbolic-ref HEAD)" = "refs/heads/side" &&
       
      -	printf "M\t%s\n" one >expect.messages &&
     -+	printf "The following paths have local changes:\nM\t%s\n" one >expect.messages &&
     ++	cat >expect.messages <<-\EOF &&
     ++	The following paths have local changes:
     ++	M	one
     ++	EOF
       	test_cmp expect.messages messages &&
       
       	fill "M	one" "A	three" "D	two" >expect.main &&
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	test_grep "git stash drop" actual &&
      +	test_grep "git stash pop" actual &&
      +	test_grep "The following paths have local changes" actual &&
     -+	git show --format=%B --diff-merges=1 refs/stash >actual &&
     ++	git log -p -1 --format="%gs%n%B" -g --diff-merges=1 refs/stash >actual &&
      +	sed /^index/d actual >actual.trimmed &&
      +	cat >expect <<-EOF &&
     ++	autostash while switching to ${SQ}side${SQ}
      +	On main: autostash while switching to ${SQ}side${SQ}
      +
      +	diff --git a/one b/one
     @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
      +	>another-file.t &&
      +	fill 1 2 3 4 5 >one &&
      +	test_must_fail git checkout -m @{-1} 2>err &&
     -+	test_grep "would be overwritten by checkout" err &&
     -+	test_grep "another-file.t" err
     ++	q_to_tab >expect <<-\EOF &&
     ++	error: The following untracked working tree files would be overwritten by checkout:
     ++	Qanother-file.t
     ++	Please move or remove them before you switch branches.
     ++	Aborting
     ++	Applied autostash.
     ++	EOF
     ++	test_cmp expect err
      +'
      +
       test_expect_success 'switch to another branch while carrying a deletion' '

-- 
gitgitgadget

[PATCH v16 1/5] stash: add --label-ours, --label-theirs, --label-base for apply

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Allow callers of "git stash apply" to pass custom labels for conflict
markers instead of the default "Updated upstream" and "Stashed changes".
Document the new options and add a test.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-stash.adoc | 11 ++++++++++-
 builtin/stash.c              | 28 ++++++++++++++++++++--------
 t/t3903-stash.sh             | 24 ++++++++++++++++++++++++
 xdiff/xmerge.c               |  6 +++---
 4 files changed, 57 insertions(+), 12 deletions(-)

diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
index b05c990ecd..50bb89f483 100644
--- a/Documentation/git-stash.adoc
+++ b/Documentation/git-stash.adoc
@@ -12,7 +12,7 @@ git stash list [<log-options>]
 git stash show [-u | --include-untracked | --only-untracked] [<diff-options>] [<stash>]
 git stash drop [-q | --quiet] [<stash>]
 git stash pop [--index] [-q | --quiet] [<stash>]
-git stash apply [--index] [-q | --quiet] [<stash>]
+git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]
 git stash branch <branchname> [<stash>]
 git stash [push] [-p | --patch] [-S | --staged] [-k | --[no-]keep-index] [-q | --quiet]
 	     [-u | --include-untracked] [-a | --all] [(-m | --message) <message>]
@@ -195,6 +195,15 @@ the index's ones. However, this can fail, when you have conflicts
 (which are stored in the index, where you therefore can no longer
 apply the changes as they were originally).
 
+`--label-ours=<label>`::
+`--label-theirs=<label>`::
+`--label-base=<label>`::
+	These options are only valid for the `apply` command.
++
+Use the given labels in conflict markers instead of the default
+"Updated upstream", "Stashed changes", and "Stash base".
+`--label-base` only has an effect with merge.conflictStyle=diff3.
+
 `-k`::
 `--keep-index`::
 `--no-keep-index`::
diff --git a/builtin/stash.c b/builtin/stash.c
index 0d27b2fb1f..32dbc97b47 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -44,7 +44,7 @@
 #define BUILTIN_STASH_POP_USAGE \
 	N_("git stash pop [--index] [-q | --quiet] [<stash>]")
 #define BUILTIN_STASH_APPLY_USAGE \
-	N_("git stash apply [--index] [-q | --quiet] [<stash>]")
+	N_("git stash apply [--index] [-q | --quiet] [--label-ours=<label>] [--label-theirs=<label>] [--label-base=<label>] [<stash>]")
 #define BUILTIN_STASH_BRANCH_USAGE \
 	N_("git stash branch <branchname> [<stash>]")
 #define BUILTIN_STASH_STORE_USAGE \
@@ -591,7 +591,9 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 }
 
 static int do_apply_stash(const char *prefix, struct stash_info *info,
-			  int index, int quiet)
+			  int index, int quiet,
+			  const char *label_ours, const char *label_theirs,
+			  const char *label_base)
 {
 	int clean, ret;
 	int has_index = index;
@@ -643,9 +645,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	init_ui_merge_options(&o, the_repository);
 
-	o.branch1 = "Updated upstream";
-	o.branch2 = "Stashed changes";
-	o.ancestor = "Stash base";
+	o.branch1 = label_ours ? label_ours : "Updated upstream";
+	o.branch2 = label_theirs ? label_theirs : "Stashed changes";
+	o.ancestor = label_base ? label_base : "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -723,11 +725,18 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	int ret = -1;
 	int quiet = 0;
 	int index = use_index;
+	const char *label_ours = NULL, *label_theirs = NULL, *label_base = NULL;
 	struct stash_info info = STASH_INFO_INIT;
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("be quiet, only report errors")),
 		OPT_BOOL(0, "index", &index,
 			 N_("attempt to recreate the index")),
+		OPT_STRING(0, "label-ours", &label_ours, N_("label"),
+			   N_("label for the upstream side in conflict markers")),
+		OPT_STRING(0, "label-theirs", &label_theirs, N_("label"),
+			   N_("label for the stashed side in conflict markers")),
+		OPT_STRING(0, "label-base", &label_base, N_("label"),
+			   N_("label for the base in diff3 conflict markers")),
 		OPT_END()
 	};
 
@@ -737,7 +746,8 @@ static int apply_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info(&info, argc, argv))
 		goto cleanup;
 
-	ret = do_apply_stash(prefix, &info, index, quiet);
+	ret = do_apply_stash(prefix, &info, index, quiet,
+			     label_ours, label_theirs, label_base);
 cleanup:
 	free_stash_info(&info);
 	return ret;
@@ -836,7 +846,8 @@ static int pop_stash(int argc, const char **argv, const char *prefix,
 	if (get_stash_info_assert(&info, argc, argv))
 		goto cleanup;
 
-	if ((ret = do_apply_stash(prefix, &info, index, quiet)))
+	if ((ret = do_apply_stash(prefix, &info, index, quiet,
+				  NULL, NULL, NULL)))
 		printf_ln(_("The stash entry is kept in case "
 			    "you need it again."));
 	else
@@ -877,7 +888,8 @@ static int branch_stash(int argc, const char **argv, const char *prefix,
 	strvec_push(&cp.args, oid_to_hex(&info.b_commit));
 	ret = run_command(&cp);
 	if (!ret)
-		ret = do_apply_stash(prefix, &info, 1, 0);
+		ret = do_apply_stash(prefix, &info, 1, 0,
+				     NULL, NULL, NULL);
 	if (!ret && info.is_stash_ref)
 		ret = do_drop_stash(&info, 0);
 
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 70879941c2..bdaad22e1f 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -56,6 +56,7 @@ setup_stash() {
 	git add other-file &&
 	test_tick &&
 	git commit -m initial &&
+	git tag initial &&
 	echo 2 >file &&
 	git add file &&
 	echo 3 >file &&
@@ -1790,4 +1791,27 @@ test_expect_success 'stash.index=false overridden by --index' '
 	test_cmp expect file
 '
 
+test_expect_success 'apply with custom conflict labels' '
+	git reset --hard initial &&
+	test_commit label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit label-upstream conflict-file upstream-content &&
+	test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
+	test_grep "^<<<<<<< UP" conflict-file &&
+	test_grep "^||||||| Stash base" conflict-file &&
+	test_grep "^>>>>>>> STASH" conflict-file
+'
+
+test_expect_success 'apply with empty conflict labels' '
+	git reset --hard initial &&
+	test_commit empty-label-base conflict-file base-content &&
+	echo stashed >conflict-file &&
+	git stash push -m "stashed" &&
+	test_commit empty-label-upstream conflict-file upstream-content &&
+	test_must_fail git stash apply --label-ours= --label-theirs= &&
+	test_grep "^<<<<<<<$" conflict-file &&
+	test_grep "^>>>>>>>$" conflict-file
+'
+
 test_done
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 29dad98c49..659ad4ec97 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -199,9 +199,9 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 			      int size, int i, int style,
 			      xdmerge_t *m, char *dest, int marker_size)
 {
-	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
-	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
-	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
+	int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);
 	int needs_cr = is_cr_needed(xe1, xe2, m);
 
 	if (marker_size <= 0)
-- 
gitgitgadget

[PATCH v16 2/5] sequencer: allow create_autostash to run silently

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a silent parameter to create_autostash_internal and introduce
create_autostash_ref_silent so that callers can create an autostash
without printing the "Created autostash" message.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/merge.c |  6 ++++--
 sequencer.c     | 17 +++++++++++------
 sequencer.h     |  3 ++-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index 2cbce56f8d..3ebe190ef1 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1672,7 +1672,8 @@ int cmd_merge(int argc,
 		}
 
 		if (autostash)
-			create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					     NULL, false);
 		if (checkout_fast_forward(the_repository,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
@@ -1764,7 +1765,8 @@ int cmd_merge(int argc,
 		die_ff_impossible();
 
 	if (autostash)
-		create_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		create_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				     NULL, false);
 
 	/* We are going to make a new commit. */
 	git_committer_info(IDENT_STRICT);
diff --git a/sequencer.c b/sequencer.c
index b7d8dca47f..ff5258f481 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4657,7 +4657,9 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 
 static void create_autostash_internal(struct repository *r,
 				      const char *path,
-				      const char *refname)
+				      const char *refname,
+				      const char *message,
+				      bool silent)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct lock_file lock_file = LOCK_INIT;
@@ -4679,7 +4681,8 @@ static void create_autostash_internal(struct repository *r,
 		struct object_id oid;
 
 		strvec_pushl(&stash.args,
-			     "stash", "create", "autostash", NULL);
+			     "stash", "create",
+			     message ? message : "autostash", NULL);
 		stash.git_cmd = 1;
 		stash.no_stdin = 1;
 		strbuf_reset(&buf);
@@ -4702,7 +4705,8 @@ static void create_autostash_internal(struct repository *r,
 					&oid, null_oid(the_hash_algo), 0, UPDATE_REFS_DIE_ON_ERR);
 		}
 
-		printf(_("Created autostash: %s\n"), buf.buf);
+		if (!silent)
+			printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
 		discard_index(r->index);
@@ -4714,12 +4718,13 @@ static void create_autostash_internal(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path)
 {
-	create_autostash_internal(r, path, NULL);
+	create_autostash_internal(r, path, NULL, NULL, false);
 }
 
-void create_autostash_ref(struct repository *r, const char *refname)
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent)
 {
-	create_autostash_internal(r, NULL, refname);
+	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
diff --git a/sequencer.h b/sequencer.h
index a6fa670c7c..02d2d9db06 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -229,7 +229,8 @@ void commit_post_rewrite(struct repository *r,
 			 const struct object_id *new_head);
 
 void create_autostash(struct repository *r, const char *path);
-void create_autostash_ref(struct repository *r, const char *refname);
+void create_autostash_ref(struct repository *r, const char *refname,
+			  const char *message, bool silent);
 int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
-- 
gitgitgadget

[PATCH v16 3/5] sequencer: teach autostash apply to take optional conflict marker labels

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add label_ours, label_theirs, label_base, and stash_msg parameters to
apply_autostash_ref() and the autostash apply machinery so callers can
pass custom conflict marker labels through to
"git stash apply --label-ours/--label-theirs/--label-base", as well as
a custom stash message for "git stash store -m".

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/commit.c |  3 ++-
 builtin/merge.c  |  9 ++++++---
 sequencer.c      | 38 +++++++++++++++++++++++++++++---------
 sequencer.h      |  4 +++-
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index a3e52ac9ca..28f6174503 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1979,7 +1979,8 @@ int cmd_commit(int argc,
 				     &oid, flags);
 	}
 
-	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+			    NULL, NULL, NULL, NULL);
 
 cleanup:
 	free_commit_extra_headers(extra);
diff --git a/builtin/merge.c b/builtin/merge.c
index 3ebe190ef1..aacf8c524e 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -537,7 +537,8 @@ static void finish(struct commit *head_commit,
 	run_hooks_l(the_repository, "post-merge", squash ? "1" : "0", NULL);
 
 	if (new_head)
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 	strbuf_release(&reflog_message);
 }
 
@@ -1678,7 +1679,8 @@ int cmd_merge(int argc,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
 					  overwrite_ignore)) {
-			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+					    NULL, NULL, NULL, NULL);
 			ret = 1;
 			goto done;
 		}
@@ -1851,7 +1853,8 @@ int cmd_merge(int argc,
 		else
 			fprintf(stderr, _("Merge with strategy %s failed.\n"),
 				use_strategies[0]->name);
-		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH");
+		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
+				    NULL, NULL, NULL, NULL);
 		ret = 2;
 		goto done;
 	} else if (best_strategy == wt_strategy)
diff --git a/sequencer.c b/sequencer.c
index ff5258f481..7c0376d9e4 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4727,7 +4727,10 @@ void create_autostash_ref(struct repository *r, const char *refname,
 	create_autostash_internal(r, NULL, refname, message, silent);
 }
 
-static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4738,6 +4741,12 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		child.no_stderr = 1;
 		strvec_push(&child.args, "stash");
 		strvec_push(&child.args, "apply");
+		if (label_ours)
+			strvec_pushf(&child.args, "--label-ours=%s", label_ours);
+		if (label_theirs)
+			strvec_pushf(&child.args, "--label-theirs=%s", label_theirs);
+		if (label_base)
+			strvec_pushf(&child.args, "--label-base=%s", label_base);
 		strvec_push(&child.args, stash_oid);
 		ret = run_command(&child);
 	}
@@ -4751,7 +4760,7 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 		strvec_push(&store.args, "stash");
 		strvec_push(&store.args, "store");
 		strvec_push(&store.args, "-m");
-		strvec_push(&store.args, "autostash");
+		strvec_push(&store.args, stash_msg ? stash_msg : "autostash");
 		strvec_push(&store.args, "-q");
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
@@ -4782,7 +4791,8 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	}
 	strbuf_trim(&stash_oid);
 
-	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
+				      NULL, NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4801,11 +4811,14 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
-				    int attempt_apply)
+				    int attempt_apply,
+				    const char *label_ours, const char *label_theirs,
+				    const char *label_base,
+				    const char *stash_msg)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
@@ -4821,7 +4834,9 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 		return error(_("autostash reference is a symref"));
 
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
-	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply);
+	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
+				       label_ours, label_theirs, label_base,
+				       stash_msg);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4831,12 +4846,17 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 
 int save_autostash_ref(struct repository *r, const char *refname)
 {
-	return apply_save_autostash_ref(r, refname, 0);
+	return apply_save_autostash_ref(r, refname, 0,
+					NULL, NULL, NULL, NULL);
 }
 
-int apply_autostash_ref(struct repository *r, const char *refname)
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg)
 {
-	return apply_save_autostash_ref(r, refname, 1);
+	return apply_save_autostash_ref(r, refname, 1,
+					label_ours, label_theirs, label_base,
+					stash_msg);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 02d2d9db06..3164bd437d 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -235,7 +235,9 @@ int save_autostash(const char *path);
 int save_autostash_ref(struct repository *r, const char *refname);
 int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
-int apply_autostash_ref(struct repository *r, const char *refname);
+int apply_autostash_ref(struct repository *r, const char *refname,
+			const char *label_ours, const char *label_theirs,
+			const char *label_base, const char *stash_msg);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH v16 4/5] checkout: rollback lock on early returns in merge_working_tree

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

merge_working_tree() acquires the index lock via
repo_hold_locked_index() but several early return paths exit
without calling rollback_lock_file(), leaving the lock held.
While this is currently harmless because the process exits soon
after, it becomes a problem if the function is ever called more
than once in the same process.

Add rollback_lock_file() calls to all early return paths.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/checkout.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..c80c62b37b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -783,8 +783,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	struct tree *new_tree;
 
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
-	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
+	if (repo_read_index_preload(the_repository, NULL, 0) < 0) {
+		rollback_lock_file(&lock_file);
 		return error(_("index file corrupt"));
+	}
 
 	resolve_undo_clear_index(the_repository->index);
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
@@ -797,14 +799,18 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
-		if (!new_tree)
+		if (!new_tree) {
+			rollback_lock_file(&lock_file);
 			return error(_("unable to read tree (%s)"),
 				     oid_to_hex(&new_branch_info->commit->object.oid));
+		}
 	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
-		if (ret)
+		if (ret) {
+			rollback_lock_file(&lock_file);
 			return ret;
+		}
 	} else {
 		struct tree_desc trees[2];
 		struct tree *tree;
@@ -814,6 +820,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL, NULL);
 
 		if (unmerged_index(the_repository->index)) {
+			rollback_lock_file(&lock_file);
 			error(_("you need to resolve your current index first"));
 			return 1;
 		}
@@ -857,15 +864,19 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			struct strbuf sb = STRBUF_INIT;
 			struct strbuf old_commit_shortname = STRBUF_INIT;
 
-			if (!opts->merge)
+			if (!opts->merge) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 
 			/*
 			 * Without old_branch_info->commit, the below is the same as
 			 * the two-tree unpack we already tried and failed.
 			 */
-			if (!old_branch_info->commit)
+			if (!old_branch_info->commit) {
+				rollback_lock_file(&lock_file);
 				return 1;
+			}
 			old_tree = repo_get_commit_tree(the_repository,
 							old_branch_info->commit);
 
@@ -897,8 +908,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			ret = reset_tree(new_tree,
 					 opts, 1,
 					 writeout_error, new_branch_info);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 			o.ancestor = old_branch_info->name;
 			if (!old_branch_info->name) {
 				strbuf_add_unique_abbrev(&old_commit_shortname,
@@ -920,8 +933,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 					 writeout_error, new_branch_info);
 			strbuf_release(&o.obuf);
 			strbuf_release(&old_commit_shortname);
-			if (ret)
+			if (ret) {
+				rollback_lock_file(&lock_file);
 				return ret;
+			}
 		}
 	}
 
-- 
gitgitgadget

[PATCH v16 5/5] checkout -m: autostash when switching branches

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When switching branches with "git checkout -m", the attempted merge
of local modifications may cause conflicts with the changes made on
the other branch, which the user may not want to (or may not be able
to) resolve right now.  Because there is no easy way to recover from
this situation, we discouraged users from using "checkout -m" unless
they are certain their changes are trivial and within their ability
to resolve conflicts.

Teach the -m flow to create a temporary stash before switching and
reapply it after.  On success, the stash is silently applied and
the list of locally modified paths is shown, same as a successful
"git checkout" without "-m".

If reapplying causes conflicts, the stash is kept and the user is
told they can resolve and run "git stash drop", or run "git reset
--hard" and later "git stash pop" to recover their changes.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 Documentation/git-checkout.adoc |  55 ++++++-----
 Documentation/git-switch.adoc   |  36 +++----
 builtin/checkout.c              | 161 ++++++++++++++------------------
 sequencer.c                     |  14 ++-
 t/t3420-rebase-autostash.sh     |  16 ++--
 t/t7201-co.sh                   |  71 +++++++++++++-
 t/t7600-merge.sh                |   3 +-
 xdiff-interface.c               |  12 +++
 xdiff-interface.h               |   1 +
 9 files changed, 219 insertions(+), 150 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..a8b3b8c2e2 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -251,20 +251,19 @@ working tree, by copying them from elsewhere, extracting a tarball, etc.
 	are different between the current branch and the branch to
 	which you are switching, the command refuses to switch
 	branches in order to preserve your modifications in context.
-	However, with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch
-	is done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	With this option, the conflicting local changes are
+	automatically stashed before the switch and reapplied
+	afterwards.  If the local changes do not overlap with the
+	differences between branches, the switch proceeds without
+	stashing.  If reapplying the stash results in conflicts, the
+	entry is saved to the stash list.  Resolve the conflicts
+	and run `git stash drop` when done, or clear the working
+	tree (e.g. with `git reset --hard`) before running `git stash
+	pop` later to re-apply your changes.
 +
 When checking out paths from the index, this option lets you recreate
 the conflicted merge in the specified paths.  This option cannot be
 used when checking out paths from a tree-ish.
-+
-When switching branches with `--merge`, staged changes may be lost.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -578,38 +577,36 @@ $ git checkout mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a
-three-way merge:
+You can give the `-m` flag to the command, which will carry your local
+changes to the new branch:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
+Applied autostash.
+Switched to branch 'mytopic'
+The following paths have local changes:
+M	frotz
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
 === 3. Merge conflict
 
-When a merge conflict happens during switching branches with
-the `-m` option, you would see something like this:
+When the `--merge` (`-m`) option is given and the local changes
+overlap with the changes in the branch we're switching to, the
+changes are stashed and reapplied after the switch.  If this
+process results in conflicts, the stash entry is saved and a
+message is printed:
 
 ------------
 $ git checkout -m mytopic
-Auto-merging frotz
-ERROR: Merge conflict in frotz
-fatal: merge program failed
-------------
-
-At this point, `git diff` shows the changes cleanly merged as in
-the previous example, as well as the changes in the conflicted
-files.  Edit and resolve the conflict and mark it resolved with
-`git add` as usual:
-
-------------
-$ edit frotz
-$ git add frotz
+Your local changes are stashed, however applying them
+resulted in conflicts.  You can either resolve the conflicts
+and then discard the stash with "git stash drop", or, if you
+do not want to resolve them now, run "git reset --hard" and
+apply the local changes later by running "git stash pop".
 ------------
 
 CONFIGURATION
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..d6c4f229a5 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -123,18 +123,19 @@ variable.
 
 `-m`::
 `--merge`::
-	If you have local modifications to one or more files that are
-	different between the current branch and the branch to which
-	you are switching, the command refuses to switch branches in
-	order to preserve your modifications in context.  However,
-	with this option, a three-way merge between the current
-	branch, your working tree contents, and the new branch is
-	done, and you will be on the new branch.
-+
-When a merge conflict happens, the index entries for conflicting
-paths are left unmerged, and you need to resolve the conflicts
-and mark the resolved paths with `git add` (or `git rm` if the merge
-should result in deletion of the path).
+	If you have local modifications to one or more files that
+	are different between the current branch and the branch to
+	which you are switching, the command normally refuses to
+	switch branches in order to preserve your modifications in
+	context.  However, with this option, the conflicting local
+	changes are automatically stashed before the switch and
+	reapplied afterwards.  If the local changes do not overlap
+	with the differences between branches, the switch proceeds
+	without stashing.  If reapplying the stash results in
+	conflicts, the entry is saved to the stash list.  Resolve
+	the conflicts and run `git stash drop` when done, or clear
+	the working tree (e.g. with `git reset --hard`) before
+	running `git stash pop` later to re-apply your changes.
 
 `--conflict=<style>`::
 	The same as `--merge` option above, but changes the way the
@@ -217,15 +218,18 @@ $ git switch mytopic
 error: You have local changes to 'frotz'; not switching branches.
 ------------
 
-You can give the `-m` flag to the command, which would try a three-way
-merge:
+You can give the `-m` flag to the command, which will carry your local
+changes to the new branch:
 
 ------------
 $ git switch -m mytopic
-Auto-merging frotz
+Applied autostash.
+Switched to branch 'mytopic'
+The following paths have local changes:
+M	frotz
 ------------
 
-After this three-way merge, the local modifications are _not_
+After the switch, the local modifications are reapplied and are _not_
 registered in your index file, so `git diff` would show you what
 changes you made since the tip of the new branch.
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index c80c62b37b..3e9c456fad 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -17,7 +17,6 @@
 #include "merge-ll.h"
 #include "lockfile.h"
 #include "mem-pool.h"
-#include "merge-ort-wrappers.h"
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
@@ -30,6 +29,7 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "sequencer.h"
 #include "setup.h"
 #include "submodule.h"
 #include "symlinks.h"
@@ -99,6 +99,8 @@ struct checkout_opts {
 	.auto_advance = 1, \
 }
 
+#define MERGE_WORKING_TREE_UNPACK_FAILED (-2)
+
 struct branch_info {
 	char *name; /* The short name used */
 	char *path; /* The full name of a real branch */
@@ -753,9 +755,9 @@ static void setup_branch_path(struct branch_info *branch)
 	branch->path = strbuf_detach(&buf, NULL);
 }
 
-static void init_topts(struct unpack_trees_options *topts, int merge,
+static void init_topts(struct unpack_trees_options *topts,
 		       int show_progress, int overwrite_ignore,
-		       struct commit *old_commit)
+		       bool quiet)
 {
 	memset(topts, 0, sizeof(*topts));
 	topts->head_idx = -1;
@@ -767,7 +769,7 @@ static void init_topts(struct unpack_trees_options *topts, int merge,
 	topts->initial_checkout = is_index_unborn(the_repository->index);
 	topts->update = 1;
 	topts->merge = 1;
-	topts->quiet = merge && old_commit;
+	topts->quiet = quiet;
 	topts->verbose_update = show_progress;
 	topts->fn = twoway_merge;
 	topts->preserve_ignored = !overwrite_ignore;
@@ -776,6 +778,7 @@ static void init_topts(struct unpack_trees_options *topts, int merge,
 static int merge_working_tree(const struct checkout_opts *opts,
 			      struct branch_info *old_branch_info,
 			      struct branch_info *new_branch_info,
+			      bool quiet,
 			      int *writeout_error)
 {
 	int ret;
@@ -826,8 +829,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		}
 
 		/* 2-way merge to the new branch */
-		init_topts(&topts, opts->merge, opts->show_progress,
-			   opts->overwrite_ignore, old_branch_info->commit);
+		init_topts(&topts, opts->show_progress,
+			   opts->overwrite_ignore, quiet);
 		init_checkout_metadata(&topts.meta, new_branch_info->refname,
 				       new_branch_info->commit ?
 				       &new_branch_info->commit->object.oid :
@@ -853,90 +856,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		ret = unpack_trees(2, trees, &topts);
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
-			/*
-			 * Unpack couldn't do a trivial merge; either
-			 * give up or do a real merge, depending on
-			 * whether the merge flag was used.
-			 */
-			struct tree *work;
-			struct tree *old_tree;
-			struct merge_options o;
-			struct strbuf sb = STRBUF_INIT;
-			struct strbuf old_commit_shortname = STRBUF_INIT;
-
-			if (!opts->merge) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-
-			/*
-			 * Without old_branch_info->commit, the below is the same as
-			 * the two-tree unpack we already tried and failed.
-			 */
-			if (!old_branch_info->commit) {
-				rollback_lock_file(&lock_file);
-				return 1;
-			}
-			old_tree = repo_get_commit_tree(the_repository,
-							old_branch_info->commit);
-
-			if (repo_index_has_changes(the_repository, old_tree, &sb))
-				die(_("cannot continue with staged changes in "
-				      "the following files:\n%s"), sb.buf);
-			strbuf_release(&sb);
-
-			/* Do more real merge */
-
-			/*
-			 * We update the index fully, then write the
-			 * tree from the index, then merge the new
-			 * branch with the current tree, with the old
-			 * branch as the base. Then we reset the index
-			 * (but not the working tree) to the new
-			 * branch, leaving the working tree as the
-			 * merged version, but skipping unmerged
-			 * entries in the index.
-			 */
-
-			add_files_to_cache(the_repository, NULL, NULL, NULL, 0,
-					0, 0);
-			init_ui_merge_options(&o, the_repository);
-			o.verbosity = 0;
-			work = write_in_core_index_as_tree(the_repository,
-							   the_repository->index);
-
-			ret = reset_tree(new_tree,
-					 opts, 1,
-					 writeout_error, new_branch_info);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
-			o.ancestor = old_branch_info->name;
-			if (!old_branch_info->name) {
-				strbuf_add_unique_abbrev(&old_commit_shortname,
-							 &old_branch_info->commit->object.oid,
-							 DEFAULT_ABBREV);
-				o.ancestor = old_commit_shortname.buf;
-			}
-			o.branch1 = new_branch_info->name;
-			o.branch2 = "local";
-			o.conflict_style = opts->conflict_style;
-			ret = merge_ort_nonrecursive(&o,
-						     new_tree,
-						     work,
-						     old_tree);
-			if (ret < 0)
-				die(NULL);
-			ret = reset_tree(new_tree,
-					 opts, 0,
-					 writeout_error, new_branch_info);
-			strbuf_release(&o.obuf);
-			strbuf_release(&old_commit_shortname);
-			if (ret) {
-				rollback_lock_file(&lock_file);
-				return ret;
-			}
+			rollback_lock_file(&lock_file);
+			return MERGE_WORKING_TREE_UNPACK_FAILED;
 		}
 	}
 
@@ -1181,6 +1102,10 @@ static int switch_branches(const struct checkout_opts *opts,
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
+	int created_autostash = 0;
+	struct strbuf old_commit_shortname = STRBUF_INIT;
+	struct strbuf autostash_msg = STRBUF_INIT;
+	const char *stash_label_base = NULL;
 
 	trace2_cmd_mode("branch");
 
@@ -1218,11 +1143,49 @@ static int switch_branches(const struct checkout_opts *opts,
 			do_merge = 0;
 	}
 
+	if (old_branch_info.name) {
+		stash_label_base = old_branch_info.name;
+	} else if (old_branch_info.commit) {
+		strbuf_add_unique_abbrev(&old_commit_shortname,
+					 &old_branch_info.commit->object.oid,
+					 DEFAULT_ABBREV);
+		stash_label_base = old_commit_shortname.buf;
+	}
+
 	if (do_merge) {
-		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
+					 opts->merge, &writeout_error);
+		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
+			strbuf_addf(&autostash_msg,
+				    "autostash while switching to '%s'",
+				    new_branch_info->name);
+			create_autostash_ref(the_repository,
+					     "CHECKOUT_AUTOSTASH_HEAD",
+					     autostash_msg.buf, true);
+			created_autostash = 1;
+			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
+						 false, &writeout_error);
+		}
+		if (created_autostash) {
+			if (opts->conflict_style >= 0) {
+				struct strbuf cfg = STRBUF_INIT;
+				strbuf_addf(&cfg, "merge.conflictStyle=%s",
+					    conflict_style_name(opts->conflict_style));
+				git_config_push_parameter(cfg.buf);
+				strbuf_release(&cfg);
+			}
+			apply_autostash_ref(the_repository,
+					    "CHECKOUT_AUTOSTASH_HEAD",
+					    new_branch_info->name,
+					    "local",
+					    stash_label_base,
+					    autostash_msg.buf);
+		}
 		if (ret) {
 			branch_info_release(&old_branch_info);
-			return ret;
+			strbuf_release(&old_commit_shortname);
+			strbuf_release(&autostash_msg);
+			return ret < 0 ? 1 : ret;
 		}
 	}
 
@@ -1231,8 +1194,22 @@ static int switch_branches(const struct checkout_opts *opts,
 
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
+	if (created_autostash) {
+		discard_index(the_repository->index);
+		if (repo_read_index(the_repository) < 0)
+			die(_("index file corrupt"));
+
+		if (!opts->quiet && new_branch_info->commit) {
+			printf(_("The following paths have local changes:\n"));
+			show_local_changes(&new_branch_info->commit->object,
+					   &opts->diff_options);
+		}
+	}
+
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 	branch_info_release(&old_branch_info);
+	strbuf_release(&old_commit_shortname);
+	strbuf_release(&autostash_msg);
 
 	return ret || writeout_error;
 }
diff --git a/sequencer.c b/sequencer.c
index 7c0376d9e4..746f85a442 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4765,15 +4765,19 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
+		else if (attempt_apply)
+			fprintf(stderr,
+				_("Your local changes are stashed, however applying them\n"
+				  "resulted in conflicts.  You can either resolve the conflicts\n"
+				  "and then discard the stash with \"git stash drop\", or, if you\n"
+				  "do not want to resolve them now, run \"git reset --hard\" and\n"
+				  "apply the local changes later by running \"git stash pop\".\n"));
 		else
 			fprintf(stderr,
-				_("%s\n"
+				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"),
-				attempt_apply ?
-				_("Applying autostash resulted in conflicts.") :
-				_("Autostash exists; creating a new stash entry."));
+				  " \"git stash drop\" at any time.\n"));
 	}
 
 	return ret;
diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
index ad3ba6a984..f0bbc476ff 100755
--- a/t/t3420-rebase-autostash.sh
+++ b/t/t3420-rebase-autostash.sh
@@ -61,18 +61,22 @@ create_expected_failure_apply () {
 	First, rewinding head to replay your work on top of it...
 	Applying: second commit
 	Applying: third commit
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however applying them
+	resulted in conflicts.  You can either resolve the conflicts
+	and then discard the stash with "git stash drop", or, if you
+	do not want to resolve them now, run "git reset --hard" and
+	apply the local changes later by running "git stash pop".
 	EOF
 }
 
 create_expected_failure_merge () {
 	cat >expected <<-EOF
 	$(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
-	Applying autostash resulted in conflicts.
-	Your changes are safe in the stash.
-	You can run "git stash pop" or "git stash drop" at any time.
+	Your local changes are stashed, however applying them
+	resulted in conflicts.  You can either resolve the conflicts
+	and then discard the stash with "git stash drop", or, if you
+	do not want to resolve them now, run "git reset --hard" and
+	apply the local changes later by running "git stash pop".
 	Successfully rebased and updated refs/heads/rebased-feature-branch.
 	EOF
 }
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..7613b1d2a4 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -102,7 +102,10 @@ test_expect_success 'checkout -m with dirty tree' '
 
 	test "$(git symbolic-ref HEAD)" = "refs/heads/side" &&
 
-	printf "M\t%s\n" one >expect.messages &&
+	cat >expect.messages <<-\EOF &&
+	The following paths have local changes:
+	M	one
+	EOF
 	test_cmp expect.messages messages &&
 
 	fill "M	one" "A	three" "D	two" >expect.main &&
@@ -210,6 +213,72 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp expect two
 '
 
+test_expect_success 'checkout -m with mixed staged and unstaged changes' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 0 x y z >same &&
+	git add same &&
+	fill 1 2 3 4 5 6 7 >one &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "Applied autostash" actual &&
+	fill 0 x y z >expect &&
+	test_cmp expect same &&
+	fill 1 2 3 4 5 6 7 >expect &&
+	test_cmp expect one
+'
+
+test_expect_success 'checkout -m creates a recoverable stash on conflict' '
+	git checkout -f main &&
+	git clean -f &&
+
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout side 2>stderr &&
+	test_grep "Your local changes" stderr &&
+	git checkout -m side >actual 2>&1 &&
+	test_grep "resulted in conflicts" actual &&
+	test_grep "git stash drop" actual &&
+	test_grep "git stash pop" actual &&
+	test_grep "The following paths have local changes" actual &&
+	git log -p -1 --format="%gs%n%B" -g --diff-merges=1 refs/stash >actual &&
+	sed /^index/d actual >actual.trimmed &&
+	cat >expect <<-EOF &&
+	autostash while switching to ${SQ}side${SQ}
+	On main: autostash while switching to ${SQ}side${SQ}
+
+	diff --git a/one b/one
+	--- a/one
+	+++ b/one
+	@@ -3,6 +3,3 @@
+	 3
+	 4
+	 5
+	-6
+	-7
+	-8
+	EOF
+	test_cmp expect actual.trimmed &&
+	git stash drop &&
+	git reset --hard
+'
+
+test_expect_success 'checkout -m which would overwrite untracked file' '
+	git checkout -f --detach main &&
+	test_commit another-file &&
+	git checkout HEAD^ &&
+	>another-file.t &&
+	fill 1 2 3 4 5 >one &&
+	test_must_fail git checkout -m @{-1} 2>err &&
+	q_to_tab >expect <<-\EOF &&
+	error: The following untracked working tree files would be overwritten by checkout:
+	Qanother-file.t
+	Please move or remove them before you switch branches.
+	Aborting
+	Applied autostash.
+	EOF
+	test_cmp expect err
+'
+
 test_expect_success 'switch to another branch while carrying a deletion' '
 	git checkout -f main &&
 	git reset --hard &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 9838094b66..f877d9a433 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -914,7 +914,8 @@ test_expect_success 'merge with conflicted --autostash changes' '
 	git diff >expect &&
 	test_when_finished "test_might_fail git stash drop" &&
 	git merge --autostash c3 2>err &&
-	test_grep "Applying autostash resulted in conflicts." err &&
+	test_grep "applying them" err &&
+	test_grep "resulted in conflicts" err &&
 	git show HEAD:file >merge-result &&
 	test_cmp result.1-9 merge-result &&
 	git stash show -p >actual &&
diff --git a/xdiff-interface.c b/xdiff-interface.c
index f043330f2a..5ee2b96d0a 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -325,6 +325,18 @@ int parse_conflict_style_name(const char *value)
 		return -1;
 }
 
+const char *conflict_style_name(int style)
+{
+	switch (style) {
+	case XDL_MERGE_DIFF3:
+		return "diff3";
+	case XDL_MERGE_ZEALOUS_DIFF3:
+		return "zdiff3";
+	default:
+		return "merge";
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value,
diff --git a/xdiff-interface.h b/xdiff-interface.h
index fbc4ceec40..ce54e1c0e0 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -55,6 +55,7 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);
 struct config_context;
 int parse_conflict_style_name(const char *value);
+const char *conflict_style_name(int style);
 int git_xmerge_config(const char *var, const char *value,
 		      const struct config_context *ctx, void *cb);
 extern int git_xmerge_style;
-- 
gitgitgadget

Re: [PATCH v16 5/5] checkout -m: autostash when switching branches

[Phillip Wood]

Hi Harald

On 28/04/2026 19:39, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
>   	if (do_merge) {
> -		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
> +		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
> +					 opts->merge, &writeout_error);
> +		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
> +			strbuf_addf(&autostash_msg,
> +				    "autostash while switching to '%s'",
> +				    new_branch_info->name);
> +			create_autostash_ref(the_repository,
> +					     "CHECKOUT_AUTOSTASH_HEAD",
> +					     autostash_msg.buf, true);

If there are no local changes then doing this is pointless - it means 
unpack_trees() failed for another reason. Having said that the current 
code also tries a 3-way merge unconditionally so I think we can happily 
leave this for the future as #leftoverbits

> +			created_autostash = 1;
> +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
> +						 false, &writeout_error);
> +		}
> +		if (created_autostash) {
> +			if (opts->conflict_style >= 0) {
> +				struct strbuf cfg = STRBUF_INIT;
> +				strbuf_addf(&cfg, "merge.conflictStyle=%s",
> +					    conflict_style_name(opts->conflict_style));
> +				git_config_push_parameter(cfg.buf);
> +				strbuf_release(&cfg);
> +			}
> +			apply_autostash_ref(the_repository,
> +					    "CHECKOUT_AUTOSTASH_HEAD",
> +					    new_branch_info->name,
> +					    "local",
> +					    stash_label_base,
> +					    autostash_msg.buf);
> +		}
>   		if (ret) {
>   			branch_info_release(&old_branch_info);
> -			return ret;
> +			strbuf_release(&old_commit_shortname);
> +			strbuf_release(&autostash_msg);
> +			return ret < 0 ? 1 : ret;
>   		}
>   	}

If popping the stash created merge conflicts then it would be nice to 
print a blank line before the message about which branch we've switched 
to so that it is visually separated from the conflicts advice. That 
would mean apply_autostash_ref() would have to tell us if there we're 
conflicts. Again we can happily leave that for the future as #leftoverbits

Thanks

Phillip

Re: [PATCH v16 0/5] checkout: 'autostash' for branch switching

[Phillip Wood]

Hi Harald

On 28/04/2026 19:39, Harald Nordgren via GitGitGadget wrote:
>   * Updated the git checkout and git switch docs to show the actual output
>     when using -m to carry local changes across a branch switch, and changed
>     "would carry" to "will carry".
>   * Rewrote the merge-conflict example in both docs to match the new, more
>     concise message printed on autostash conflicts.
>   * Replaced the show_unpack_errors flag and old_commit parameter in
>     merge_working_tree()/init_topts() with a plain quiet boolean, so the
>     caller decides directly whether to suppress unpack errors.
>   * Tightened the 'checkout -m with dirty tree' test by replacing a printf
>     with a heredoc.
>   * Made the 'checkout -m creates a recoverable stash on conflict' test also
>     assert the reflog subject of the new stash entry.
>   * Replaced two test_grep calls in the 'checkout -m which would overwrite
>     untracked file' test with a single test_cmp, which also catches a
>     regression where the "would be overwritten" message could end up printed
>     twice.

That all sounds good and the range-diff below looks as I would expect it 
to. I've left some suggestions for possible future work on patch 5 but I 
think this is ready to be merged as-is.

Thanks for working on it

Phillip

> Harald Nordgren (5):
>    stash: add --label-ours, --label-theirs, --label-base for apply
>    sequencer: allow create_autostash to run silently
>    sequencer: teach autostash apply to take optional conflict marker
>      labels
>    checkout: rollback lock on early returns in merge_working_tree
>    checkout -m: autostash when switching branches
> 
>   Documentation/git-checkout.adoc |  55 +++++------
>   Documentation/git-stash.adoc    |  11 ++-
>   Documentation/git-switch.adoc   |  36 ++++---
>   builtin/checkout.c              | 166 +++++++++++++++-----------------
>   builtin/commit.c                |   3 +-
>   builtin/merge.c                 |  15 ++-
>   builtin/stash.c                 |  28 ++++--
>   sequencer.c                     |  69 +++++++++----
>   sequencer.h                     |   7 +-
>   t/t3420-rebase-autostash.sh     |  16 +--
>   t/t3903-stash.sh                |  24 +++++
>   t/t7201-co.sh                   |  71 +++++++++++++-
>   t/t7600-merge.sh                |   3 +-
>   xdiff-interface.c               |  12 +++
>   xdiff-interface.h               |   1 +
>   xdiff/xmerge.c                  |   6 +-
>   16 files changed, 343 insertions(+), 180 deletions(-)
> 
> 
> base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v16
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v16
> Pull-Request: https://github.com/git/git/pull/2234
> 
> Range-diff vs v15:
> 
>   1:  aba8e6a9dc = 1:  aba8e6a9dc stash: add --label-ours, --label-theirs, --label-base for apply
>   2:  89e0bfa803 = 2:  89e0bfa803 sequencer: allow create_autostash to run silently
>   3:  a428ce7328 = 3:  a428ce7328 sequencer: teach autostash apply to take optional conflict marker labels
>   4:  f358424085 = 4:  f358424085 checkout: rollback lock on early returns in merge_working_tree
>   5:  96b14db827 ! 5:  07d25fda91 checkout -m: autostash when switching branches
>       @@ Documentation/git-checkout.adoc: $ git checkout mytopic
>         
>        -You can give the `-m` flag to the command, which would try a
>        -three-way merge:
>       -+You can give the `-m` flag to the command, which would carry your local
>       ++You can give the `-m` flag to the command, which will carry your local
>        +changes to the new branch:
>         
>         ------------
>         $ git checkout -m mytopic
>        -Auto-merging frotz
>       ++Applied autostash.
>        +Switched to branch 'mytopic'
>       ++The following paths have local changes:
>       ++M	frotz
>         ------------
>         
>        -After this three-way merge, the local modifications are _not_
>       @@ Documentation/git-checkout.adoc: $ git checkout mytopic
>         
>        -When a merge conflict happens during switching branches with
>        -the `-m` option, you would see something like this:
>       -+When the `--merge` (`-m`) option is in effect and the locally
>       -+modified files overlap with files that need to be updated by the
>       -+branch switch, the changes are stashed and reapplied after the
>       -+switch.  If this process results in conflicts, a stash entry is saved
>       -+and made available in `git stash list`:
>       ++When the `--merge` (`-m`) option is given and the local changes
>       ++overlap with the changes in the branch we're switching to, the
>       ++changes are stashed and reapplied after the switch.  If this
>       ++process results in conflicts, the stash entry is saved and a
>       ++message is printed:
>         
>         ------------
>         $ git checkout -m mytopic
>       @@ Documentation/git-checkout.adoc: $ git checkout mytopic
>        -ERROR: Merge conflict in frotz
>        -fatal: merge program failed
>        -------------
>       -+Your local changes are stashed, however, applying it to carry
>       -+forward your local changes resulted in conflicts:
>       -
>       +-
>        -At this point, `git diff` shows the changes cleanly merged as in
>        -the previous example, as well as the changes in the conflicted
>        -files.  Edit and resolve the conflict and mark it resolved with
>        -`git add` as usual:
>       -+ - You can try resolving them now.  If you resolved them
>       -+   successfully, discard the stash entry with "git stash drop".
>       -
>       -+ - Alternatively you can "git reset --hard" if you do not want
>       -+   to deal with them right now, and later "git stash pop" to
>       -+   recover your local changes.
>       - ------------
>       +-
>       +-------------
>        -$ edit frotz
>        -$ git add frotz
>       --------------
>       -+
>       -+You can try resolving the conflicts now.  Edit the conflicting files
>       -+and mark them resolved with `git add` as usual, then run `git stash
>       -+drop` to discard the stash entry.  Alternatively, you can clear the
>       -+working tree with `git reset --hard` and recover your local changes
>       -+later with `git stash pop`.
>       ++Your local changes are stashed, however applying them
>       ++resulted in conflicts.  You can either resolve the conflicts
>       ++and then discard the stash with "git stash drop", or, if you
>       ++do not want to resolve them now, run "git reset --hard" and
>       ++apply the local changes later by running "git stash pop".
>       + ------------
>         
>         CONFIGURATION
>       - -------------
>        
>         ## Documentation/git-switch.adoc ##
>        @@ Documentation/git-switch.adoc: variable.
>       @@ Documentation/git-switch.adoc: $ git switch mytopic
>         
>        -You can give the `-m` flag to the command, which would try a three-way
>        -merge:
>       -+You can give the `-m` flag to the command, which would carry your local
>       ++You can give the `-m` flag to the command, which will carry your local
>        +changes to the new branch:
>         
>         ------------
>         $ git switch -m mytopic
>        -Auto-merging frotz
>       ++Applied autostash.
>        +Switched to branch 'mytopic'
>       ++The following paths have local changes:
>       ++M	frotz
>         ------------
>         
>        -After this three-way merge, the local modifications are _not_
>       @@ builtin/checkout.c: struct checkout_opts {
>         	char *name; /* The short name used */
>         	char *path; /* The full name of a real branch */
>        @@ builtin/checkout.c: static void setup_branch_path(struct branch_info *branch)
>       + 	branch->path = strbuf_detach(&buf, NULL);
>       + }
>         
>       - static void init_topts(struct unpack_trees_options *topts, int merge,
>       +-static void init_topts(struct unpack_trees_options *topts, int merge,
>       ++static void init_topts(struct unpack_trees_options *topts,
>         		       int show_progress, int overwrite_ignore,
>        -		       struct commit *old_commit)
>       -+		       struct commit *old_commit, bool show_unpack_errors)
>       ++		       bool quiet)
>         {
>         	memset(topts, 0, sizeof(*topts));
>         	topts->head_idx = -1;
>       @@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, i
>         	topts->update = 1;
>         	topts->merge = 1;
>        -	topts->quiet = merge && old_commit;
>       -+	topts->quiet = merge && old_commit && !show_unpack_errors;
>       ++	topts->quiet = quiet;
>         	topts->verbose_update = show_progress;
>         	topts->fn = twoway_merge;
>         	topts->preserve_ignored = !overwrite_ignore;
>       @@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, i
>         static int merge_working_tree(const struct checkout_opts *opts,
>         			      struct branch_info *old_branch_info,
>         			      struct branch_info *new_branch_info,
>       --			      int *writeout_error)
>       -+			      int *writeout_error,
>       -+			      bool show_unpack_errors)
>       ++			      bool quiet,
>       + 			      int *writeout_error)
>         {
>         	int ret;
>       - 	struct lock_file lock_file = LOCK_INIT;
>        @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts,
>       + 		}
>         
>         		/* 2-way merge to the new branch */
>       - 		init_topts(&topts, opts->merge, opts->show_progress,
>       +-		init_topts(&topts, opts->merge, opts->show_progress,
>        -			   opts->overwrite_ignore, old_branch_info->commit);
>       -+			   opts->overwrite_ignore, old_branch_info->commit,
>       -+			   show_unpack_errors);
>       ++		init_topts(&topts, opts->show_progress,
>       ++			   opts->overwrite_ignore, quiet);
>         		init_checkout_metadata(&topts.meta, new_branch_info->refname,
>         				       new_branch_info->commit ?
>         				       &new_branch_info->commit->object.oid :
>       @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>         	if (do_merge) {
>        -		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
>        +		ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
>       -+					 &writeout_error, false);
>       ++					 opts->merge, &writeout_error);
>        +		if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) {
>        +			strbuf_addf(&autostash_msg,
>        +				    "autostash while switching to '%s'",
>       @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
>        +					     autostash_msg.buf, true);
>        +			created_autostash = 1;
>        +			ret = merge_working_tree(opts, &old_branch_info, new_branch_info,
>       -+						 &writeout_error, true);
>       ++						 false, &writeout_error);
>        +		}
>        +		if (created_autostash) {
>        +			if (opts->conflict_style >= 0) {
>       @@ t/t7201-co.sh: test_expect_success 'checkout -m with dirty tree' '
>         	test "$(git symbolic-ref HEAD)" = "refs/heads/side" &&
>         
>        -	printf "M\t%s\n" one >expect.messages &&
>       -+	printf "The following paths have local changes:\nM\t%s\n" one >expect.messages &&
>       ++	cat >expect.messages <<-\EOF &&
>       ++	The following paths have local changes:
>       ++	M	one
>       ++	EOF
>         	test_cmp expect.messages messages &&
>         
>         	fill "M	one" "A	three" "D	two" >expect.main &&
>       @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
>        +	test_grep "git stash drop" actual &&
>        +	test_grep "git stash pop" actual &&
>        +	test_grep "The following paths have local changes" actual &&
>       -+	git show --format=%B --diff-merges=1 refs/stash >actual &&
>       ++	git log -p -1 --format="%gs%n%B" -g --diff-merges=1 refs/stash >actual &&
>        +	sed /^index/d actual >actual.trimmed &&
>        +	cat >expect <<-EOF &&
>       ++	autostash while switching to ${SQ}side${SQ}
>        +	On main: autostash while switching to ${SQ}side${SQ}
>        +
>        +	diff --git a/one b/one
>       @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 <branch>'
>        +	>another-file.t &&
>        +	fill 1 2 3 4 5 >one &&
>        +	test_must_fail git checkout -m @{-1} 2>err &&
>       -+	test_grep "would be overwritten by checkout" err &&
>       -+	test_grep "another-file.t" err
>       ++	q_to_tab >expect <<-\EOF &&
>       ++	error: The following untracked working tree files would be overwritten by checkout:
>       ++	Qanother-file.t
>       ++	Please move or remove them before you switch branches.
>       ++	Aborting
>       ++	Applied autostash.
>       ++	EOF
>       ++	test_cmp expect err
>        +'
>        +
>         test_expect_success 'switch to another branch while carrying a deletion' '
> 

[PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> That all sounds good and the range-diff below looks as I would expect it
> to. I've left some suggestions for possible future work on patch 5 but I
> think this is ready to be merged as-is.
> 
> Thanks for working on it

Thank you too!


Harald

[PATCH v16 0/5] checkout: 'autostash' for branch switching

[Harald Nordgren]

Is this ready to be merged?


Harald

Re: [PATCH v16 0/5] checkout: 'autostash' for branch switching

[Phillip Wood]

Hi Harald

On 07/05/2026 21:11, Harald Nordgren wrote:
 > Is this ready to be merged?

You can see the current status by reading the latest what's cooking 
email from Junio. I don't think he's officially back online until next 
week so I wouldn't be surprised if this hasn't been merged yet. You can 
always check

	git log --merges --grep hn/ origin/next

to see which of your topics are in next.

Thanks

Phillip

[PATCH] remote: use plural-only message for diverged branch status

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Drop Q_() singular form and use _() with the plural string only.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    format_branch_comparison: diverged message has only plural case

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2239%2FHaraldNordgren%2Fformat_branch_comparison__plural-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2239/HaraldNordgren/format_branch_comparison__plural-v1
Pull-Request: https://github.com/git/git/pull/2239

 remote.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/remote.c b/remote.c
index 7ca2a6501b..12136dfa23 100644
--- a/remote.c
+++ b/remote.c
@@ -2307,13 +2307,8 @@ static void format_branch_comparison(struct strbuf *sb,
 				_("  (use \"git pull\" to update your local branch)\n"));
 	} else {
 		strbuf_addf(sb,
-			Q_("Your branch and '%s' have diverged,\n"
-			       "and have %d and %d different commit each, "
-			       "respectively.\n",
-			   "Your branch and '%s' have diverged,\n"
-			       "and have %d and %d different commits each, "
-			       "respectively.\n",
-			   ours + theirs),
+			_("Your branch and '%s' have diverged,\n"
+			       "and have %d and %d different commits each, respectively.\n"),
 			branch_name, ours, theirs);
 		if (use_divergence_advice && advice_enabled(ADVICE_STATUS_HINTS))
 			strbuf_addstr(sb,

base-commit: dc6ecd5354dca88d51b6d6562777fc8fc10d77e1
-- 
gitgitgadget

Re: [PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

>> Harald Nordgren (2):
>>   refactor format_branch_comparison in preparation
>>   status: show comparison with push remote tracking branch
>>
>>  remote.c                 | 183 ++++++++++++++++++++-------
>>  t/t6040-tracking-info.sh | 262 +++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 403 insertions(+), 42 deletions(-)
>>
>>
>> base-commit: d529f3a197364881746f558e5652f0236131eb86
>> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2138%2FHaraldNordgren%2Fahead_of_main_status-v20
>> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2138/HaraldNordgren/ahead_of_main_status-v20
>> Pull-Request: https://github.com/git/git/pull/2138
>>
>> Range-diff vs v19:
>>
>>  1:  451d7a4986 ! 1:  bb3e00863b refactor format_branch_comparison in preparation
>>      @@ remote.c: int format_tracking_info(struct branch *branch, struct strbuf *sb,
>>        		if (advice_enabled(ADVICE_STATUS_HINTS))
>>        			strbuf_addstr(sb,
>>        				_("  (use \"git pull\" to update your local branch)\n"));
>>      -@@ remote.c: int format_tracking_info(struct branch *branch, struct strbuf *sb,
>>      - 			       "and have %d and %d different commits each, "
>>      - 			       "respectively.\n",
>>      - 			   ours + theirs),
>>      + 	} else {
>>      + 		strbuf_addf(sb,
>>      +-			Q_("Your branch and '%s' have diverged,\n"
>>      +-			       "and have %d and %d different commit each, "
>>      +-			       "respectively.\n",
>>      +-			   "Your branch and '%s' have diverged,\n"
>>      +-			       "and have %d and %d different commits each, "
>>      +-			       "respectively.\n",
>>      +-			   ours + theirs),
>>       -			base, ours, theirs);
>>      ++			"Your branch and '%s' have diverged,\n"
>>      ++			       "and have %d and %d different commits each, respectively.\n",
>>       +			branch_name, ours, theirs);
>>        		if (show_divergence_advice &&
>>        		    advice_enabled(ADVICE_STATUS_HINTS))
>
> Could you not mix the ours+theirs thing into the same step?  Either
> make it a standalone patch to clean up before or after your main 2
> patches, or leave it totally outside the series and send it after
> this series settles.

Making a change that was left out of https://lore.kernel.org/git/xmqqzf6lqs9w.fsf@gitster.g/

Harald

Re: [PATCH v5] checkout: extend --track with a "fetch" mode to refresh start-point

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> A common workflow is:
>
>     git fetch origin
>     git checkout -b new_branch --track origin/some-branch
>
> The first command exists so the second sees an up-to-date view of the
> remote. If it is forgotten, origin/some-branch points at a stale
> commit and the new local branch is created from the wrong start
> point.

As I pointed out multiple times, I prefer not to see this called
"wrong".  Even if you did not "forget", somebody may be pushing
after you fetched and you may end up forking from a "stale" commit.
So not fetching is not inherently "wrong", simply because that is
how real world works.  Multiple people working in a distributed
environment does not give you absolute garantee that you will be "up
to date", ever, which makes it wrong to call anything that is not
"up to date" a "wrong starting point".

> This only matters when the user is setting up tracking and
> expects the new branch to start at the freshest tip; for a one-off
> checkout of an arbitrary commit there is no reason to "freshen" the
> start-point.

I do not think "arbitrary" fits in this workflow description.

If anything, "I'd take anything that the remote repository happens
to have at the tip, even without having a chance to sanity checke if
that is a good starting point" is more appropriate workflow to be
described with a word "arbitrary commit".

If you are checking out without forking from there, you'd more
likely be checking out the "latest" you have fetched from the other
side, often knowing exactly what it is after checking it with "git
show origin/$topic".

> Tie the new behavior to --track for that reason:

Notice that the reader hasn't heard what "the new behaviour" is up
to this point yet?

How about rewriting everything up to and including this "Tie the new
..." line perhaps like so:

    If you want to fork your topic branch from the very latest of
    the tip of a branch your remote has, you would do:

	git fetch origin some-branch
	git checkout -b new_branch --track origin/some-branch

    Extend the "--track" option of "git checkout" and allow users to
    write

	git checkout --track=fetch -b new_branch origin/some_branch

    to (1) fetch 'some-branch' from the remote 'origin', updating
    the remote-tracking branch 'origin/some-branch', (2) arrange
    subsequent 'git pull' on 'new_branch' to interact with
    'origin/some_branch' and (3) fork 'new_branch' from it.
   
    In the value of the '--track' option, 'fetch' can be combined
    with ...

[PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> How about rewriting everything up to and including this "Tie the new
> ..." line perhaps like so:

Done!


Harald

Re: [PATCH] fetch: add fetch.pruneLocalBranches config

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> Introduce a tri-state config option that, when --prune (or
> fetch.prune / remote.<name>.prune) removes a remote-tracking
> ref, also deletes local branches whose configured upstream is
> that ref.
>
> Values:
> - false (default): no change in behavior.
> - safe: delete only if the local tip is reachable from the
>   upstream tip, preserving any unpushed work.
> - force: delete unconditionally; recoverable only via reflog.
>
> The currently checked-out branch is always preserved.

I do like the feature that allows you to identify which local
branches are already merged and prune them.  It will help users keep
their local branch namespace clean.

I however do not like to see the feature tied to "fetch".  By this,
I do not mean I do not want an option to trigger the feature when
"git fetch" is run.  What I mean is that users should have an option
to prune merged branches without having to fetch first.  And you can
then optionally trigger that machinery from "git fetch".

Of course they aleady can do something silly like

    $ git branch -d $(git branch --list | sed -e 's/^..//')

and remove all the merged branches, but compared to what is
presented here, one thing missing is that you allow pruning the
local branches that are merged only to remote-tracking branches from
a single remote.

To break the feature down to make it easier to use by our users with
various needs and workflows, we would benefit from having a
collection of smaller features that can be composed, like these:

 * "git branch --forked <remote>" lists local branches that build on
   something taken from <remote>s.  The option can be given multiple
   times to make a union of the results from individual "--forked
   <remote>".

   - <remote> may be a name of a remote, e.g., "origin" to mean all
     the remote-tracking branches "refs/remotes/origin/*", 

   - <remote> may be "origin/master" to name a specific
     remote-tracking branch.

   - There may be other handy things to cover with <remote>, like
     "--all" that may act as if you listed all the available
     <remote> on the command line.

 * "git branch --prune-merged <remote>..." is a short-hand for "git
   branch -d $(git branch --forked <remote>...".

 * "git fetch/pull --prune-merged <remote>" can trigger "git branch
   --prune-merged <remote>" after "git fetch" successfully updates
   the remote-tracking branches, which should be equivalent to what
   you have here..

Some local branches that fork from remote and have their initial
round already merged may not want to be pruned, however.  You may
have multi-stage development plans for that topic, and you know
already the second phase would want to build on top of the initial
round, not a random version of the mainline with many topics from
other folks merged in.  So you'd rather want to keep the topic
branch around after your initial round has been merged to the
upstream before you start the second phase.  This is especially true
if your topic is designed to apply to an existing release (in other
words, a bugfix) and you want to keep the second and subsequent
rounds of the topic to be applicable to the same target version
without contaminating the topic with irrelevant features from others
that happened to have been developed and merged upstream around the
same time.

And we'd need to cater to their needs.  By this, I do not mean "they
do not have to use --prune-merged", but by giving them a way to say
"this branch should not be auto-pruned with --prune-merged".

[PATCH] checkout: add --autostash option for branch switching

[Harald Nordgren]

> I do like the feature that allows you to identify which local
> branches are already merged and prune them.  It will help users keep
> their local branch namespace clean.

Nice to hear!

> To break the feature down to make it easier to use by our users with
> various needs and workflows, we would benefit from having a
> collection of smaller features that can be composed, like these:

I gave it a shot to implement these, and then I ran it one some local repos
it works really nicely!


Harald

Re: [PATCH] checkout: add --autostash option for branch switching

[Junio C Hamano]

Harald Nordgren <haraldnordgren@gmail.com> writes:

>> I do like the feature that allows you to identify which local
>> branches are already merged and prune them.  It will help users keep
>> their local branch namespace clean.
>
> Nice to hear!
>
>> To break the feature down to make it easier to use by our users with
>> various needs and workflows, we would benefit from having a
>> collection of smaller features that can be composed, like these:
>
> I gave it a shot to implement these, and then I ran it one some local repos
> it works really nicely!
>
>
> Harald

It was baffling to see a message with the subject "checkout: add
--autostash" as your reponse to my message that was a response to
"fetch: add fetch.pruneLocalBranches".