[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] 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

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

[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.

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] 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

[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]

> 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

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] 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

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

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]

> 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

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

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

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

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] 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.

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

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

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]

> 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

[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

[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]

>    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]

> > +	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

[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

[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

[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

[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] 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

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

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

[PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a --fetch option to git checkout and git switch, plus a
checkout.autoFetch config to enable it by default. When set and the
start-point argument names a configured remote (either bare, like
"origin", or prefixed, like "origin/foo"), fetch that remote before
resolving the ref. Aborts the checkout if the fetch fails.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: add --fetch to fetch remote before resolving start-point
    
    A workflow I run several times a day looks like:
    
    git fetch origin
    git checkout -b new_branch origin/some-branch
    
    
    The first command exists purely to make the second one see an up-to-date
    view of the remote. If I forget it, origin/some-branch points at a stale
    commit, and I end up creating a local branch from the wrong starting
    point.
    
    This series teaches git checkout (and git switch) a new --fetch flag
    that folds the two steps into one:
    
    git checkout --fetch -b new_branch origin/some-branch
    
    
    When the start-point argument names a configured remote — either bare
    (origin, which resolves to the remote's default branch) or in / form —
    git fetch is run before the start-point is resolved. If the fetch fails,
    the checkout aborts and no local branch is created.
    
    A new checkout.autoFetch config option enables the same behavior by
    default, for users who always want it.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v1
Pull-Request: https://github.com/git/git/pull/2281

 builtin/checkout.c    | 48 ++++++++++++++++++++++++++++++++++++++--
 t/t7201-co.sh         | 51 +++++++++++++++++++++++++++++++++++++++++++
 t/t9902-completion.sh |  1 +
 3 files changed, 98 insertions(+), 2 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..c8fbc4923b 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,7 +30,9 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 #include "submodule.h"
 #include "symlinks.h"
 #include "trace2.h"
@@ -61,6 +63,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int auto_fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -112,6 +115,34 @@ struct branch_info {
 	char *checkout;
 };
 
+static void fetch_remote_for_start_point(const char *arg)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (!arg || !*arg)
+		return;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	cmd.git_cmd = 1;
+	free(remote_name);
+	if (run_command(&cmd))
+		die(_("failed to fetch start-point '%s'"), arg);
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1237,6 +1268,10 @@ 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.autofetch")) {
+		opts->auto_fetch = git_config_bool(var, value);
+		return 0;
+	}
 
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
@@ -1942,8 +1977,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->auto_fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
@@ -2052,6 +2092,8 @@ int cmd_checkout(int argc,
 		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
 		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
 			 N_("auto advance to the next file when selecting hunks interactively")),
+		OPT_BOOL(0, "fetch", &opts.auto_fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),
 		OPT_END()
 	};
 
@@ -2102,6 +2144,8 @@ int cmd_switch(int argc,
 			 N_("second guess 'git switch <no-such-branch>'")),
 		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
 			 N_("throw away local modifications")),
+		OPT_BOOL(0, "fetch", &opts.auto_fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),
 		OPT_END()
 	};
 
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..60ddebd9c3 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,55 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
+'
+
+test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_new2 &&
+	test_commit -C fetch_upstream u_new2 &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
+	git checkout --fetch -b local_from_remote fetch_upstream &&
+	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
+'
+
+test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout.autoFetch=true enables fetching without --fetch' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_cfg &&
+	test_commit -C fetch_upstream u_cfg &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
+	git -c checkout.autoFetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
+'
+
+test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 2f9a597ec7..dc1d63669f 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
+	--fetch Z
 	--progress Z
 	--guess Z
 	--no-guess Z

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
-- 
gitgitgadget

Re: [PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Ramsay Jones]

On 24/04/2026 11:03 am, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add a --fetch option to git checkout and git switch, plus a
> checkout.autoFetch config to enable it by default. When set and the
> start-point argument names a configured remote (either bare, like
> "origin", or prefixed, like "origin/foo"), fetch that remote before
> resolving the ref. Aborts the checkout if the fetch fails.
> 
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---

[snip]

>  
> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..60ddebd9c3 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -801,4 +801,55 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
>  	test_cmp_config "" --default "" branch.main2.merge
>  '
>  
> +test_expect_success 'setup upstream for --fetch tests' '
> +	git checkout main &&
> +	git init fetch_upstream &&
> +	test_commit -C fetch_upstream u_main &&
> +	git remote add fetch_upstream fetch_upstream &&
> +	git fetch fetch_upstream &&
> +	git -C fetch_upstream checkout -b fetch_new &&
> +	test_commit -C fetch_upstream u_new
> +'
> +
> +test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
> +	git checkout main &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
> +	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
> +'
> +
> +test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_new2 &&
> +	test_commit -C fetch_upstream u_new2 &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
> +	git checkout --fetch -b local_from_remote fetch_upstream &&
> +	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
> +'
> +
> +test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
> +	git checkout main &&
> +	test_might_fail git branch -D bogus &&
> +	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
> +	test_must_fail git rev-parse --verify refs/heads/bogus
> +'
> +
> +test_expect_success 'checkout.autoFetch=true enables fetching without --fetch' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_cfg &&
> +	test_commit -C fetch_upstream u_cfg &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
> +	git -c checkout.autoFetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
> +'
> +
> +test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_switch &&
> +	test_commit -C fetch_upstream u_switch &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
> +	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
> +'
> +

I was just skimming the list (so if this is not appropriate, please just ignore) and,
although I think '--no-fetch' will probably countermand the autoFetch config, I do not
see a test that confirms it.

Thanks.

ATB,
Ramsay Jones

Re: [PATCH] checkout: add --fetch to fetch remote before resolving start-point

[D. Ben Knoble]

On Fri, Apr 24, 2026 at 6:08 AM Harald Nordgren via GitGitGadget
<gitgitgadget@gmail.com> wrote:
>
> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> Add a --fetch option to git checkout and git switch, plus a
> checkout.autoFetch config to enable it by default. When set and the
> start-point argument names a configured remote (either bare, like
> "origin", or prefixed, like "origin/foo"), fetch that remote before
> resolving the ref. Aborts the checkout if the fetch fails.
>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>     checkout: add --fetch to fetch remote before resolving start-point
>
>     A workflow I run several times a day looks like:
>
>     git fetch origin
>     git checkout -b new_branch origin/some-branch
>
>
>     The first command exists purely to make the second one see an up-to-date
>     view of the remote. If I forget it, origin/some-branch points at a stale
>     commit, and I end up creating a local branch from the wrong starting
>     point.

When you realize this, "git pull --rebase" should help correct it.

>
>     This series teaches git checkout (and git switch) a new --fetch flag
>     that folds the two steps into one:
>
>     git checkout --fetch -b new_branch origin/some-branch
>
>
>     When the start-point argument names a configured remote — either bare
>     (origin, which resolves to the remote's default branch) or in / form —
>     git fetch is run before the start-point is resolved. If the fetch fails,
>     the checkout aborts and no local branch is created.
>
>     A new checkout.autoFetch config option enables the same behavior by
>     default, for users who always want it.

I could certainly see this being convenient. (I don't have any comment
on the code at this time.)

Re: [PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Kristoffer Haugsbakk]

On Fri, Apr 24, 2026, at 12:03, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> Add a --fetch option to git checkout and git switch, plus a
> checkout.autoFetch config to enable it by default. When set and the

Why is the config not `checkout.config`? So it’s named the same as the
option (modulo snake case/camel case which is not relevant here).

> start-point argument names a configured remote (either bare, like
> "origin", or prefixed, like "origin/foo"),

It’s great that it only fetches when you have a remote-tracking branch
or alias for `<remote>/HEAD`. Doing a fetch on every <start-point> would
have been bad.

> fetch that remote before
> resolving the ref. Aborts the checkout if the fetch fails.
>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>     checkout: add --fetch to fetch remote before resolving start-point
>
>     A workflow I run several times a day looks like:
>
>     git fetch origin
>     git checkout -b new_branch origin/some-branch
>
>
>     The first command exists purely to make the second one see an up-to-date
>     view of the remote. If I forget it, origin/some-branch points at a stale
>     commit, and I end up creating a local branch from the wrong starting
>     point.
>
>     This series teaches git checkout (and git switch) a new --fetch flag
>     that folds the two steps into one:
>
>     git checkout --fetch -b new_branch origin/some-branch

The motivation for why this is being proposed maybe might as well go in
the commit message. Maybe that’s just me.

The commit message just says that “this thing is added”. Not why.

>
>
>     When the start-point argument names a configured remote — either bare
>     (origin, which resolves to the remote's default branch) or in / form —
>     git fetch is run before the start-point is resolved. If the fetch fails,
>     the checkout aborts and no local branch is created.
>
>     A new checkout.autoFetch config option enables the same behavior by
>     default, for users who always want it.
>
> Published-As:
> https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git
> pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v1
> Pull-Request: https://github.com/git/git/pull/2281
>
>  builtin/checkout.c    | 48 ++++++++++++++++++++++++++++++++++++++--
>  t/t7201-co.sh         | 51 +++++++++++++++++++++++++++++++++++++++++++
>  t/t9902-completion.sh |  1 +
>  3 files changed, 98 insertions(+), 2 deletions(-)

I guess a later version will have the changes to the documentation.

>
> diff --git a/builtin/checkout.c b/builtin/checkout.c
>[snip]
>  		argv += n;
>  		argc -= n;
>  	} else if (!opts->accept_ref && opts->from_treeish) {
> @@ -2052,6 +2092,8 @@ int cmd_checkout(int argc,
>  		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode
> (default)")),
>  		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
>  			 N_("auto advance to the next file when selecting hunks
> interactively")),
> +		OPT_BOOL(0, "fetch", &opts.auto_fetch,
> +			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),

s/remote-tracking ref/remote-tracking branch/ ?

git(1) doesn’t have a namespace for tracking refs in general.

>  		OPT_END()
>  	};
>
> @@ -2102,6 +2144,8 @@ int cmd_switch(int argc,
>  			 N_("second guess 'git switch <no-such-branch>'")),
>  		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
>  			 N_("throw away local modifications")),
> +		OPT_BOOL(0, "fetch", &opts.auto_fetch,
> +			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),

Ditto.

>  		OPT_END()
>  	};
>[snip]

Re: [PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Marc Branchaud]

On 2026-04-24 04:03, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> Add a --fetch option to git checkout and git switch, plus a
> checkout.autoFetch config to enable it by default. When set and the
> start-point argument names a configured remote (either bare, like
> "origin", or prefixed, like "origin/foo"), fetch that remote before
> resolving the ref. Aborts the checkout if the fetch fails.

Why tie the behaviour to the nature of the start-point?  That seems 
over-designed and prone to tripping people up.  Are you trying to cater 
to users who have multiple remotes?

I can imagine people who just want to do a checkout of anything after 
fetching -- maybe they want to checkout a new tag, or some other 
detached HEAD, or just an already-existing local branch.  They see that 
checkout has this nifty --fetch option so they think they can combine
	git fetch; git checkout
into a single command ... but no, only if they checkout something in a 
remote's namespace.

I don't personally feel the need for this new option, but I think you'll 
have a much easier time implementing and maintaining it if you just make 
--fetch do a plain fetch without caring about what the starting-point is.

		M.


> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>      checkout: add --fetch to fetch remote before resolving start-point
>      
>      A workflow I run several times a day looks like:
>      
>      git fetch origin
>      git checkout -b new_branch origin/some-branch
>      
>      
>      The first command exists purely to make the second one see an up-to-date
>      view of the remote. If I forget it, origin/some-branch points at a stale
>      commit, and I end up creating a local branch from the wrong starting
>      point.
>      
>      This series teaches git checkout (and git switch) a new --fetch flag
>      that folds the two steps into one:
>      
>      git checkout --fetch -b new_branch origin/some-branch
>      
>      
>      When the start-point argument names a configured remote — either bare
>      (origin, which resolves to the remote's default branch) or in / form —
>      git fetch is run before the start-point is resolved. If the fetch fails,
>      the checkout aborts and no local branch is created.
>      
>      A new checkout.autoFetch config option enables the same behavior by
>      default, for users who always want it.
> 
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v1
> Pull-Request: https://github.com/git/git/pull/2281
> 
>   builtin/checkout.c    | 48 ++++++++++++++++++++++++++++++++++++++--
>   t/t7201-co.sh         | 51 +++++++++++++++++++++++++++++++++++++++++++
>   t/t9902-completion.sh |  1 +
>   3 files changed, 98 insertions(+), 2 deletions(-)
> 
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index e031e61886..c8fbc4923b 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -30,7 +30,9 @@
>   #include "repo-settings.h"
>   #include "resolve-undo.h"
>   #include "revision.h"
> +#include "run-command.h"
>   #include "setup.h"
> +#include "strvec.h"
>   #include "submodule.h"
>   #include "symlinks.h"
>   #include "trace2.h"
> @@ -61,6 +63,7 @@ struct checkout_opts {
>   	int count_checkout_paths;
>   	int overlay_mode;
>   	int dwim_new_local_branch;
> +	int auto_fetch;
>   	int discard_changes;
>   	int accept_ref;
>   	int accept_pathspec;
> @@ -112,6 +115,34 @@ struct branch_info {
>   	char *checkout;
>   };
>   
> +static void fetch_remote_for_start_point(const char *arg)
> +{
> +	const char *slash;
> +	char *remote_name;
> +	struct remote *remote;
> +	struct child_process cmd = CHILD_PROCESS_INIT;
> +
> +	if (!arg || !*arg)
> +		return;
> +
> +	slash = strchr(arg, '/');
> +	if (slash == arg)
> +		return;
> +	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
> +
> +	remote = remote_get(remote_name);
> +	if (!remote || !remote_is_configured(remote, 1)) {
> +		free(remote_name);
> +		return;
> +	}
> +
> +	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
> +	cmd.git_cmd = 1;
> +	free(remote_name);
> +	if (run_command(&cmd))
> +		die(_("failed to fetch start-point '%s'"), arg);
> +}
> +
>   static void branch_info_release(struct branch_info *info)
>   {
>   	free(info->name);
> @@ -1237,6 +1268,10 @@ 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.autofetch")) {
> +		opts->auto_fetch = git_config_bool(var, value);
> +		return 0;
> +	}
>   
>   	if (starts_with(var, "submodule."))
>   		return git_default_submodule_config(var, value, NULL);
> @@ -1942,8 +1977,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
>   			opts->dwim_new_local_branch &&
>   			opts->track == BRANCH_TRACK_UNSPECIFIED &&
>   			!opts->new_branch;
> -		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
> -					     &new_branch_info, opts, &rev);
> +		int n;
> +
> +		if (opts->auto_fetch)
> +			fetch_remote_for_start_point(argv[0]);
> +
> +		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
> +					 &new_branch_info, opts, &rev);
>   		argv += n;
>   		argc -= n;
>   	} else if (!opts->accept_ref && opts->from_treeish) {
> @@ -2052,6 +2092,8 @@ int cmd_checkout(int argc,
>   		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
>   		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
>   			 N_("auto advance to the next file when selecting hunks interactively")),
> +		OPT_BOOL(0, "fetch", &opts.auto_fetch,
> +			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),
>   		OPT_END()
>   	};
>   
> @@ -2102,6 +2144,8 @@ int cmd_switch(int argc,
>   			 N_("second guess 'git switch <no-such-branch>'")),
>   		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
>   			 N_("throw away local modifications")),
> +		OPT_BOOL(0, "fetch", &opts.auto_fetch,
> +			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),
>   		OPT_END()
>   	};
>   
> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..60ddebd9c3 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -801,4 +801,55 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
>   	test_cmp_config "" --default "" branch.main2.merge
>   '
>   
> +test_expect_success 'setup upstream for --fetch tests' '
> +	git checkout main &&
> +	git init fetch_upstream &&
> +	test_commit -C fetch_upstream u_main &&
> +	git remote add fetch_upstream fetch_upstream &&
> +	git fetch fetch_upstream &&
> +	git -C fetch_upstream checkout -b fetch_new &&
> +	test_commit -C fetch_upstream u_new
> +'
> +
> +test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
> +	git checkout main &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
> +	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
> +'
> +
> +test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_new2 &&
> +	test_commit -C fetch_upstream u_new2 &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
> +	git checkout --fetch -b local_from_remote fetch_upstream &&
> +	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
> +'
> +
> +test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
> +	git checkout main &&
> +	test_might_fail git branch -D bogus &&
> +	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
> +	test_must_fail git rev-parse --verify refs/heads/bogus
> +'
> +
> +test_expect_success 'checkout.autoFetch=true enables fetching without --fetch' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_cfg &&
> +	test_commit -C fetch_upstream u_cfg &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
> +	git -c checkout.autoFetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
> +'
> +
> +test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_switch &&
> +	test_commit -C fetch_upstream u_switch &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
> +	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
> +'
> +
>   test_done
> diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
> index 2f9a597ec7..dc1d63669f 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
> +	--fetch Z
>   	--progress Z
>   	--guess Z
>   	--no-guess Z
> 
> base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0

Re: [PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Junio C Hamano]

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

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> Add a --fetch option to git checkout and git switch, plus a
> checkout.autoFetch config to enable it by default. When set and the
> start-point argument names a configured remote (either bare, like
> "origin", or prefixed, like "origin/foo"), fetch that remote before
> resolving the ref. Aborts the checkout if the fetch fails.
>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---

It is true that "checkout" does funny things to special case the
remote-tracking branches, like setting up the branch.<name>.merge
configuration or even inferring the name of the local branch to be
created.  

But I have to say that this one, especially the configuration
variable, goes way too far.  The usual uses of remote-tracking
branch names, e.g.,

    git log -1 origin/master
    git grep frotz origin/master
    git rev-list --count origin/maint..origin/master

to name a specific object all assume and rely on the stability of
them.  Should the configuration cause a fetch to happen before any
of these uses of remote-tracking branches for consistency?

Re: [PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Junio C Hamano]

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

> "Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
>> From: Harald Nordgren <haraldnordgren@gmail.com>
>>
>> Add a --fetch option to git checkout and git switch, plus a
>> checkout.autoFetch config to enable it by default. When set and the
>> start-point argument names a configured remote (either bare, like
>> "origin", or prefixed, like "origin/foo"), fetch that remote before
>> resolving the ref. Aborts the checkout if the fetch fails.
>>
>> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
>> ---
>
> It is true that "checkout" does funny things to special case the
> remote-tracking branches, like setting up the branch.<name>.merge
> configuration or even inferring the name of the local branch to be
> created.  
> ...
> ...  Should the configuration cause a fetch to happen before any
> of these uses of remote-tracking branches for consistency?

The last one was a rhetorical question.  I do not want to see such a
configuration variable to implicitly trigger fetching at all.

I am somewhat sympathetic to the desire "I want to be sure that I
start the new branch in a state as fresh as possible".  It is tied
to the "--track" option of "git checkout -b topic --track
origin/main".  If you are merely starting at a single arbitrary
commit, instead of anticipating to having to repeatedly sync with
the remote-tracking branch that will subsequently move, there is no
point jumping to a "freshest" commit that you haven't even seen let
alone inspected (i.e., you do not even know if it is a good base to
build on).

So instead of introducing a totally new option that can only be used
only when "--track" is given, it might make more sense to introduce
this as a variant of "--track", perhaps "--track=fetch,[in]direct"
or something like that.  And extend branch.autosetup{Merge,Rebase}
that controls what happens when a branch is created with "checkout
-t -b" or "branch --track" so that the remote-tracking branch gets
updated, perhaps.

As to "git checkout origin/main" (nothing else on the command line),
it has "magic" compared to "git checkout origin/main~0" already by
treating the parameter not just as a SHA-1 expression that names a
commit object but as a remote-tracking branch (this is necessary for
"-t").  So I am not fundamentally opposed to the idea to give an
option to treat that form specifically.

Having said all that, quite honestly, I prefer not to see any of the
above changes, including the original patch.  It leaves too many
usability questions unaddressed.  For a starter, if you interact
with a repository with two or more branches, should

   $ git checkout --track=fetch -b topic origin/main

update an unrelated remote-tracking branch origin/maint from the
same remote?  As I already said, most Git tools _depend_ on the
stability of remote-tracking branches---the desire to update the
origin/main when a new branch that builds on origin/main is created
may be a valid one, but it is unclear if that warrants updating
other remote-tracking branches only because they come from the same
remote repository.  There may be a dozen other UI/usability issues
that will be introduced if we start to "fetch from remote"
automatically, but I won't even try to be exhaustive while I am
still on a leave ;-)

Comments on Phillip's review

[Harald Nordgren]

> When you realize this, "git pull --rebase" should help correct it.

Sure. I always run with

```
git config --global pull.rebase=true
```

I love rebasing and recomdend it to all colleagues that will listen, but
it still sucks to expose yourself to a possible merge conflict when you
realize you worked hours on top of a stale main branch.

> I could certainly see this being convenient.

🙌🏻


Harald

Comments on Phillip's review

[Harald Nordgren]

> > Add a --fetch option to git checkout and git switch, plus a
> > checkout.autoFetch config to enable it by default. When set and the
> 
> Why is the config not `checkout.config`? So it’s named the same as the
> option (modulo snake case/camel case which is not relevant here).

Will rename the config to 'checkout.fetch'.

> The motivation for why this is being proposed maybe might as well go in
> the commit message. Maybe that’s just me.
> 
> The commit message just says that “this thing is added”. Not why.

I will update it.

> I guess a later version will have the changes to the documentation.

I forgot that, will add it!

> s/remote-tracking ref/remote-tracking branch/ ?
> 
> git(1) doesn’t have a namespace for tracking refs in general.

👍


Harald

Wrong subject line

[Harald Nordgren]

I know you are not Ben. Forgot to change the subject line from a previous message.


Harald

Wrong subject line

[Harald Nordgren]

I know you are not Ben. Forgot to change the subject line from a previous message.


Harald

Wrong subject line

[Harald Nordgren]

I know you are not Ben. Forgot to change the subject line from a previous message.


Harald

Multiple remotes

[Harald Nordgren]

> The last one was a rhetorical question.  I do not want to see such a
> configuration variable to implicitly trigger fetching at all.

🤣

Good to clarify that when working with me so that I don't go ahead and
implement that!

> If you are merely starting at a single arbitrary
> commit, instead of anticipating to having to repeatedly sync with
> the remote-tracking branch that will subsequently move, there is no
> point jumping to a "freshest" commit that you haven't even seen let
> alone inspected (i.e., you do not even know if it is a good base to
> build on).

Not sure I understand this sentiment. For better or worse, the latest
commit will decide what you have to work with -- unless we expect it to be
reverted or forced pushed over.

What better starting point is there?

> For a starter, if you interact
> with a repository with two or more branches, should
> 
>    $ git checkout --track=fetch -b topic origin/main
> 
> update an unrelated remote-tracking branch origin/maint from the
> same remote?  As I already said, most Git tools _depend_ on the
> stability of remote-tracking branches

This is an interesting question, and it's very likely that I am missing
some nuance here. However, with that said what option does the developer
have, you have to accept that the upstream changes constantly when others
are working on it. What good does it do to keep the "head in the sand" any
longer than necessary?

I'm not sure there is a way to fetch only 'origin/main' and avoid
'origin/maint'? Maybe, maybe, if that exists it could be useful here.

> still on a leave

Enjoy your vacation! I don't expect any response from you until you're back!


Harald

[PATCH v2] checkout: add --fetch to fetch remote before resolving start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

A common workflow is:

    git fetch origin
    git checkout -b new_branch origin/some-branch

The first command exists purely 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.

Teach checkout (and switch) a --fetch flag that folds the two steps
into one:

    git checkout --fetch -b new_branch origin/some-branch

When --fetch is given and <start-point> names a configured remote
(either bare, like "origin", or prefixed, like "origin/foo"), fetch
that remote before resolving the ref. Abort the checkout if the fetch
fails.

Also add a checkout.fetch config to enable this by default.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: add --fetch to fetch remote before resolving start-point
    
     * Rename the config from checkout.autoFetch to checkout.fetch, so it
       matches the --fetch option name.
    
     * Rename the internal struct field from auto_fetch to fetch for
       consistency with the option and config names.
    
     * Reword the commit message to lead with the problem (forgetting 'git
       fetch' and ending up with a stale start-point) before describing the
       solution.
    
     * Document --fetch / --no-fetch in git-checkout and git-switch, and
       document checkout.fetch in the config reference.
    
     * Use "remote-tracking branch" instead of "remote-tracking ref" in the
       option help text.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v2
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v1:

 1:  e2fa50ff40 ! 1:  13074c9fea checkout: add --fetch to fetch remote before resolving start-point
     @@ Metadata
       ## Commit message ##
          checkout: add --fetch to fetch remote before resolving start-point
      
     -    Add a --fetch option to git checkout and git switch, plus a
     -    checkout.autoFetch config to enable it by default. When set and the
     -    start-point argument names a configured remote (either bare, like
     -    "origin", or prefixed, like "origin/foo"), fetch that remote before
     -    resolving the ref. Aborts the checkout if the fetch fails.
     +    A common workflow is:
     +
     +        git fetch origin
     +        git checkout -b new_branch origin/some-branch
     +
     +    The first command exists purely 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.
     +
     +    Teach checkout (and switch) a --fetch flag that folds the two steps
     +    into one:
     +
     +        git checkout --fetch -b new_branch origin/some-branch
     +
     +    When --fetch is given and <start-point> names a configured remote
     +    (either bare, like "origin", or prefixed, like "origin/foo"), fetch
     +    that remote before resolving the ref. Abort the checkout if the fetch
     +    fails.
     +
     +    Also add a checkout.fetch config to enable this by default.
      
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     + ## Documentation/config/checkout.adoc ##
     +@@ Documentation/config/checkout.adoc: commands or functionality in the future.
     + 	option in `git checkout` and `git switch`. See
     + 	linkgit:git-switch[1] and linkgit:git-checkout[1].
     + 
     ++`checkout.fetch`::
     ++	Provides the default value for the `--fetch` or `--no-fetch`
     ++	option in `git checkout` and `git switch`. See
     ++	linkgit:git-switch[1] and linkgit:git-checkout[1].
     ++
     + `checkout.workers`::
     + 	The number of parallel workers to use when updating the working tree.
     + 	The default is one, i.e. sequential execution. If set to a value less
     +
     + ## Documentation/git-checkout.adoc ##
     +@@ Documentation/git-checkout.adoc: linkgit:git-config[1].
     + The default behavior can be set via the `checkout.guess` configuration
     + variable.
     + 
     ++`--fetch`::
     ++`--no-fetch`::
     ++	If _<start-point>_ names a configured remote -- either bare,
     ++	like `origin` (which resolves to the remote's default branch),
     ++	or in _<remote>/<branch>_ form -- run `git fetch` on that
     ++	remote before resolving _<start-point>_. If the fetch fails,
     ++	the checkout is aborted and no local branch is created.
     +++
     ++The default behavior can be set via the `checkout.fetch` configuration
     ++variable.
     ++
     + `-l`::
     + 	Create the new branch's reflog; see linkgit:git-branch[1] for
     + 	details.
     +
     + ## Documentation/git-switch.adoc ##
     +@@ Documentation/git-switch.adoc: ambiguous but exists on the 'origin' remote. See also
     + The default behavior can be set via the `checkout.guess` configuration
     + variable.
     + 
     ++`--fetch`::
     ++`--no-fetch`::
     ++	If _<start-point>_ names a configured remote -- either bare,
     ++	like `origin` (which resolves to the remote's default branch),
     ++	or in _<remote>/<branch>_ form -- run `git fetch` on that
     ++	remote before resolving _<start-point>_. If the fetch fails,
     ++	the switch is aborted and no local branch is created.
     +++
     ++The default behavior can be set via the `checkout.fetch` configuration
     ++variable.
     ++
     + `-f`::
     + `--force`::
     + 	An alias for `--discard-changes`.
     +
       ## builtin/checkout.c ##
      @@
       #include "repo-settings.h"
     @@ builtin/checkout.c: struct checkout_opts {
       	int count_checkout_paths;
       	int overlay_mode;
       	int dwim_new_local_branch;
     -+	int auto_fetch;
     ++	int fetch;
       	int discard_changes;
       	int accept_ref;
       	int accept_pathspec;
     @@ builtin/checkout.c: static int git_checkout_config(const char *var, const char *
       		opts->dwim_new_local_branch = git_config_bool(var, value);
       		return 0;
       	}
     -+	if (!strcmp(var, "checkout.autofetch")) {
     -+		opts->auto_fetch = git_config_bool(var, value);
     ++	if (!strcmp(var, "checkout.fetch")) {
     ++		opts->fetch = git_config_bool(var, value);
      +		return 0;
      +	}
       
     @@ builtin/checkout.c: static int checkout_main(int argc, const char **argv, const
      -					     &new_branch_info, opts, &rev);
      +		int n;
      +
     -+		if (opts->auto_fetch)
     ++		if (opts->fetch)
      +			fetch_remote_for_start_point(argv[0]);
      +
      +		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
     @@ builtin/checkout.c: int cmd_checkout(int argc,
       		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
       		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
       			 N_("auto advance to the next file when selecting hunks interactively")),
     -+		OPT_BOOL(0, "fetch", &opts.auto_fetch,
     -+			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),
     ++		OPT_BOOL(0, "fetch", &opts.fetch,
     ++			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
       		OPT_END()
       	};
       
     @@ builtin/checkout.c: int cmd_switch(int argc,
       			 N_("second guess 'git switch <no-such-branch>'")),
       		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
       			 N_("throw away local modifications")),
     -+		OPT_BOOL(0, "fetch", &opts.auto_fetch,
     -+			 N_("fetch from the remote first if <start-point> is a remote-tracking ref")),
     ++		OPT_BOOL(0, "fetch", &opts.fetch,
     ++			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
       		OPT_END()
       	};
       
     @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh
      +	test_must_fail git rev-parse --verify refs/heads/bogus
      +'
      +
     -+test_expect_success 'checkout.autoFetch=true enables fetching without --fetch' '
     ++test_expect_success 'checkout.fetch=true enables fetching without --fetch' '
      +	git checkout main &&
      +	git -C fetch_upstream checkout -b fetch_cfg &&
      +	test_commit -C fetch_upstream u_cfg &&
      +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
     -+	git -c checkout.autoFetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
     ++	git -c checkout.fetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
      +	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
      +'
      +


 Documentation/config/checkout.adoc |  5 +++
 Documentation/git-checkout.adoc    | 11 +++++++
 Documentation/git-switch.adoc      | 11 +++++++
 builtin/checkout.c                 | 48 ++++++++++++++++++++++++++--
 t/t7201-co.sh                      | 51 ++++++++++++++++++++++++++++++
 t/t9902-completion.sh              |  1 +
 6 files changed, 125 insertions(+), 2 deletions(-)

diff --git a/Documentation/config/checkout.adoc b/Documentation/config/checkout.adoc
index e35d212969..c95f72b38e 100644
--- a/Documentation/config/checkout.adoc
+++ b/Documentation/config/checkout.adoc
@@ -22,6 +22,11 @@ commands or functionality in the future.
 	option in `git checkout` and `git switch`. See
 	linkgit:git-switch[1] and linkgit:git-checkout[1].
 
+`checkout.fetch`::
+	Provides the default value for the `--fetch` or `--no-fetch`
+	option in `git checkout` and `git switch`. See
+	linkgit:git-switch[1] and linkgit:git-checkout[1].
+
 `checkout.workers`::
 	The number of parallel workers to use when updating the working tree.
 	The default is one, i.e. sequential execution. If set to a value less
diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..f20e2f4c8c 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -201,6 +201,17 @@ linkgit:git-config[1].
 The default behavior can be set via the `checkout.guess` configuration
 variable.
 
+`--fetch`::
+`--no-fetch`::
+	If _<start-point>_ names a configured remote -- either bare,
+	like `origin` (which resolves to the remote's default branch),
+	or in _<remote>/<branch>_ form -- run `git fetch` on that
+	remote before resolving _<start-point>_. If the fetch fails,
+	the checkout is aborted and no local branch is created.
++
+The default behavior can be set via the `checkout.fetch` configuration
+variable.
+
 `-l`::
 	Create the new branch's reflog; see linkgit:git-branch[1] for
 	details.
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..3826ed9066 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -110,6 +110,17 @@ ambiguous but exists on the 'origin' remote. See also
 The default behavior can be set via the `checkout.guess` configuration
 variable.
 
+`--fetch`::
+`--no-fetch`::
+	If _<start-point>_ names a configured remote -- either bare,
+	like `origin` (which resolves to the remote's default branch),
+	or in _<remote>/<branch>_ form -- run `git fetch` on that
+	remote before resolving _<start-point>_. If the fetch fails,
+	the switch is aborted and no local branch is created.
++
+The default behavior can be set via the `checkout.fetch` configuration
+variable.
+
 `-f`::
 `--force`::
 	An alias for `--discard-changes`.
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..b2a34f0f00 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,7 +30,9 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 #include "submodule.h"
 #include "symlinks.h"
 #include "trace2.h"
@@ -61,6 +63,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -112,6 +115,34 @@ struct branch_info {
 	char *checkout;
 };
 
+static void fetch_remote_for_start_point(const char *arg)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (!arg || !*arg)
+		return;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	cmd.git_cmd = 1;
+	free(remote_name);
+	if (run_command(&cmd))
+		die(_("failed to fetch start-point '%s'"), arg);
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1237,6 +1268,10 @@ 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.fetch")) {
+		opts->fetch = git_config_bool(var, value);
+		return 0;
+	}
 
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
@@ -1942,8 +1977,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
@@ -2052,6 +2092,8 @@ int cmd_checkout(int argc,
 		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
 		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
 			 N_("auto advance to the next file when selecting hunks interactively")),
+		OPT_BOOL(0, "fetch", &opts.fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
 		OPT_END()
 	};
 
@@ -2102,6 +2144,8 @@ int cmd_switch(int argc,
 			 N_("second guess 'git switch <no-such-branch>'")),
 		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
 			 N_("throw away local modifications")),
+		OPT_BOOL(0, "fetch", &opts.fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
 		OPT_END()
 	};
 
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..f5729f0831 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,55 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
+'
+
+test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_new2 &&
+	test_commit -C fetch_upstream u_new2 &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
+	git checkout --fetch -b local_from_remote fetch_upstream &&
+	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
+'
+
+test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout.fetch=true enables fetching without --fetch' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_cfg &&
+	test_commit -C fetch_upstream u_cfg &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
+	git -c checkout.fetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
+'
+
+test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 2f9a597ec7..dc1d63669f 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
+	--fetch Z
 	--progress Z
 	--guess Z
 	--no-guess Z

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
-- 
gitgitgadget

Re: Multiple remotes

[Ben Knoble]

> Le 25 avr. 2026 à 13:58, Harald Nordgren <haraldnordgren@gmail.com> a écrit :
> 
> 
>> 
>> The last one was a rhetorical question.  I do not want to see such a
>> configuration variable to implicitly trigger fetching at all.
> 
> 🤣
> 
> Good to clarify that when working with me so that I don't go ahead and
> implement that!
> 
>> If you are merely starting at a single arbitrary
>> commit, instead of anticipating to having to repeatedly sync with
>> the remote-tracking branch that will subsequently move, there is no
>> point jumping to a "freshest" commit that you haven't even seen let
>> alone inspected (i.e., you do not even know if it is a good base to
>> build on).
> 
> Not sure I understand this sentiment. For better or worse, the latest
> commit will decide what you have to work with -- unless we expect it to be
> reverted or forced pushed over.
> 
> What better starting point is there?
> 
>> For a starter, if you interact
>> with a repository with two or more branches, should
>> 
>>   $ git checkout --track=fetch -b topic origin/main
>> 
>> update an unrelated remote-tracking branch origin/maint from the
>> same remote?  As I already said, most Git tools _depend_ on the
>> stability of remote-tracking branches
> 
> This is an interesting question, and it's very likely that I am missing
> some nuance here. However, with that said what option does the developer
> have, you have to accept that the upstream changes constantly when others
> are working on it. What good does it do to keep the "head in the sand" any
> longer than necessary?
> 
> I'm not sure there is a way to fetch only 'origin/main' and avoid
> 'origin/maint'? Maybe, maybe, if that exists it could be useful here.

Isn’t that exactly what

    git fetch origin main

does? (Might need to expand the refspec.)

> 
>> still on a leave
> 
> Enjoy your vacation! I don't expect any response from you until you're back!
> 
> 
> Harald
> 

gh

[Harald Nordgren]

> Isn’t that exactly what
> 
>     git fetch origin main
> 
> does? (Might need to expand the refspec.)

Very good point, I will update it!


Harald

Re: Wrong subject line

[Kristoffer Haugsbakk]

On Sat, Apr 25, 2026, at 19:44, Harald Nordgren wrote:
> I know you are not Ben. Forgot to change the subject line from a
> previous message.

You mean I’m not Phillip. ;)

    Subject: Comments on Phillip's review

I don’t understand why you change the email subjects so often. Right now
I had three “Wrong subject line” in my inbox with lost threading
(webmail client) with the only way to distinguish them being that I was
the the CC on this one.

Most of the time whole 100-email threads like patch series never change
the subject. And to me it is easier to keep track of those “RE: [PATCH
v5] florb: drop glorb” than if someone changes the subject to e.g.
“Regarding memory leaks” because someone found a memory leak in a
review. Because that was a reply to an email from two days ago, but I’ve
been a away for a week so I think it’s a new thread about
something else.

That’s just my experience. My amateur webmail setup doesn’t really
matter here since I just dip in/interrupt threads when I feel like it.

[PATCH v3] checkout: add --fetch to fetch remote before resolving start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

A common workflow is:

    git fetch origin
    git checkout -b new_branch origin/some-branch

The first command exists purely 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.

Teach checkout (and switch) a --fetch flag that folds the two steps
into one:

    git checkout --fetch -b new_branch origin/some-branch

When --fetch is given and <start-point> is in <remote>/<branch> form,
run "git fetch <remote> <branch>" before resolving the ref. This
narrows the fetch to the requested branch so that other
remote-tracking branches are left untouched -- many tools rely on the
stability of remote-tracking refs between explicit fetches. If
<start-point> is a bare remote name like "origin" (which resolves to
that remote's default branch), "git fetch <remote>" is run instead,
since the target branch is not known up front. Abort the checkout if
the fetch fails.

Also add a checkout.fetch config to enable this by default.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: add --fetch to fetch remote before resolving start-point
    
    When <start-point> is in <remote>/<branch> form, only fetch that one
    branch instead of the whole remote, so unrelated remote-tracking
    branches stay stable. The bare-remote form (e.g. "origin") still fetches
    everything.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v3
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v2:

 1:  13074c9fea ! 1:  df7b63862c checkout: add --fetch to fetch remote before resolving start-point
     @@ Commit message
      
              git checkout --fetch -b new_branch origin/some-branch
      
     -    When --fetch is given and <start-point> names a configured remote
     -    (either bare, like "origin", or prefixed, like "origin/foo"), fetch
     -    that remote before resolving the ref. Abort the checkout if the fetch
     -    fails.
     +    When --fetch is given and <start-point> is in <remote>/<branch> form,
     +    run "git fetch <remote> <branch>" before resolving the ref. This
     +    narrows the fetch to the requested branch so that other
     +    remote-tracking branches are left untouched -- many tools rely on the
     +    stability of remote-tracking refs between explicit fetches. If
     +    <start-point> is a bare remote name like "origin" (which resolves to
     +    that remote's default branch), "git fetch <remote>" is run instead,
     +    since the target branch is not known up front. Abort the checkout if
     +    the fetch fails.
      
          Also add a checkout.fetch config to enable this by default.
      
     @@ Documentation/git-checkout.adoc: linkgit:git-config[1].
       
      +`--fetch`::
      +`--no-fetch`::
     -+	If _<start-point>_ names a configured remote -- either bare,
     -+	like `origin` (which resolves to the remote's default branch),
     -+	or in _<remote>/<branch>_ form -- run `git fetch` on that
     -+	remote before resolving _<start-point>_. If the fetch fails,
     -+	the checkout is aborted and no local branch is created.
     ++	If _<start-point>_ refers to a remote-tracking branch, fetch
     ++	from that remote before resolving it. When _<start-point>_ is
     ++	in _<remote>/<branch>_ form, only that branch is updated; when
     ++	it is a bare remote name (e.g. `origin`), the whole remote is
     ++	fetched. If the fetch fails, the checkout is aborted.
      ++
      +The default behavior can be set via the `checkout.fetch` configuration
      +variable.
     @@ Documentation/git-switch.adoc: ambiguous but exists on the 'origin' remote. See
       
      +`--fetch`::
      +`--no-fetch`::
     -+	If _<start-point>_ names a configured remote -- either bare,
     -+	like `origin` (which resolves to the remote's default branch),
     -+	or in _<remote>/<branch>_ form -- run `git fetch` on that
     -+	remote before resolving _<start-point>_. If the fetch fails,
     -+	the switch is aborted and no local branch is created.
     ++	If _<start-point>_ refers to a remote-tracking branch, fetch
     ++	from that remote before resolving it. When _<start-point>_ is
     ++	in _<remote>/<branch>_ form, only that branch is updated; when
     ++	it is a bare remote name (e.g. `origin`), the whole remote is
     ++	fetched. If the fetch fails, the switch is aborted.
      ++
      +The default behavior can be set via the `checkout.fetch` configuration
      +variable.
     @@ builtin/checkout.c: struct branch_info {
      +	}
      +
      +	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
     ++	if (slash && slash[1])
     ++		strvec_push(&cmd.args, slash + 1);
      +	cmd.git_cmd = 1;
      +	free(remote_name);
      +	if (run_command(&cmd))
     @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh
      +	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
      +'
      +
     ++test_expect_success 'checkout --fetch <remote>/<branch> leaves other tracking branches untouched' '
     ++	git checkout main &&
     ++	git -C fetch_upstream checkout -b fetch_target &&
     ++	test_commit -C fetch_upstream u_target_pre &&
     ++	git -C fetch_upstream checkout -b fetch_other &&
     ++	test_commit -C fetch_upstream u_other_pre &&
     ++	git fetch fetch_upstream &&
     ++	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
     ++	git -C fetch_upstream checkout fetch_target &&
     ++	test_commit -C fetch_upstream u_target_post &&
     ++	git -C fetch_upstream checkout fetch_other &&
     ++	test_commit -C fetch_upstream u_other_post &&
     ++	git checkout --fetch -b local_target fetch_upstream/fetch_target &&
     ++	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
     ++	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
     ++'
     ++
      +test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
      +	git checkout main &&
      +	git -C fetch_upstream checkout -b fetch_new2 &&


 Documentation/config/checkout.adoc |  5 +++
 Documentation/git-checkout.adoc    | 11 +++++
 Documentation/git-switch.adoc      | 11 +++++
 builtin/checkout.c                 | 50 +++++++++++++++++++++-
 t/t7201-co.sh                      | 68 ++++++++++++++++++++++++++++++
 t/t9902-completion.sh              |  1 +
 6 files changed, 144 insertions(+), 2 deletions(-)

diff --git a/Documentation/config/checkout.adoc b/Documentation/config/checkout.adoc
index e35d212969..c95f72b38e 100644
--- a/Documentation/config/checkout.adoc
+++ b/Documentation/config/checkout.adoc
@@ -22,6 +22,11 @@ commands or functionality in the future.
 	option in `git checkout` and `git switch`. See
 	linkgit:git-switch[1] and linkgit:git-checkout[1].
 
+`checkout.fetch`::
+	Provides the default value for the `--fetch` or `--no-fetch`
+	option in `git checkout` and `git switch`. See
+	linkgit:git-switch[1] and linkgit:git-checkout[1].
+
 `checkout.workers`::
 	The number of parallel workers to use when updating the working tree.
 	The default is one, i.e. sequential execution. If set to a value less
diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..f5cc1ced74 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -201,6 +201,17 @@ linkgit:git-config[1].
 The default behavior can be set via the `checkout.guess` configuration
 variable.
 
+`--fetch`::
+`--no-fetch`::
+	If _<start-point>_ refers to a remote-tracking branch, fetch
+	from that remote before resolving it. When _<start-point>_ is
+	in _<remote>/<branch>_ form, only that branch is updated; when
+	it is a bare remote name (e.g. `origin`), the whole remote is
+	fetched. If the fetch fails, the checkout is aborted.
++
+The default behavior can be set via the `checkout.fetch` configuration
+variable.
+
 `-l`::
 	Create the new branch's reflog; see linkgit:git-branch[1] for
 	details.
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..29743bafea 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -110,6 +110,17 @@ ambiguous but exists on the 'origin' remote. See also
 The default behavior can be set via the `checkout.guess` configuration
 variable.
 
+`--fetch`::
+`--no-fetch`::
+	If _<start-point>_ refers to a remote-tracking branch, fetch
+	from that remote before resolving it. When _<start-point>_ is
+	in _<remote>/<branch>_ form, only that branch is updated; when
+	it is a bare remote name (e.g. `origin`), the whole remote is
+	fetched. If the fetch fails, the switch is aborted.
++
+The default behavior can be set via the `checkout.fetch` configuration
+variable.
+
 `-f`::
 `--force`::
 	An alias for `--discard-changes`.
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..8d810fe2fa 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,7 +30,9 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 #include "submodule.h"
 #include "symlinks.h"
 #include "trace2.h"
@@ -61,6 +63,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -112,6 +115,36 @@ struct branch_info {
 	char *checkout;
 };
 
+static void fetch_remote_for_start_point(const char *arg)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (!arg || !*arg)
+		return;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	if (slash && slash[1])
+		strvec_push(&cmd.args, slash + 1);
+	cmd.git_cmd = 1;
+	free(remote_name);
+	if (run_command(&cmd))
+		die(_("failed to fetch start-point '%s'"), arg);
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1237,6 +1270,10 @@ 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.fetch")) {
+		opts->fetch = git_config_bool(var, value);
+		return 0;
+	}
 
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
@@ -1942,8 +1979,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
@@ -2052,6 +2094,8 @@ int cmd_checkout(int argc,
 		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
 		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
 			 N_("auto advance to the next file when selecting hunks interactively")),
+		OPT_BOOL(0, "fetch", &opts.fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
 		OPT_END()
 	};
 
@@ -2102,6 +2146,8 @@ int cmd_switch(int argc,
 			 N_("second guess 'git switch <no-such-branch>'")),
 		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
 			 N_("throw away local modifications")),
+		OPT_BOOL(0, "fetch", &opts.fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
 		OPT_END()
 	};
 
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..cf2ceb4052 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,72 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
+'
+
+test_expect_success 'checkout --fetch <remote>/<branch> leaves other tracking branches untouched' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_target &&
+	test_commit -C fetch_upstream u_target_pre &&
+	git -C fetch_upstream checkout -b fetch_other &&
+	test_commit -C fetch_upstream u_other_pre &&
+	git fetch fetch_upstream &&
+	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
+	git -C fetch_upstream checkout fetch_target &&
+	test_commit -C fetch_upstream u_target_post &&
+	git -C fetch_upstream checkout fetch_other &&
+	test_commit -C fetch_upstream u_other_post &&
+	git checkout --fetch -b local_target fetch_upstream/fetch_target &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
+'
+
+test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_new2 &&
+	test_commit -C fetch_upstream u_new2 &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
+	git checkout --fetch -b local_from_remote fetch_upstream &&
+	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
+'
+
+test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout.fetch=true enables fetching without --fetch' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_cfg &&
+	test_commit -C fetch_upstream u_cfg &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
+	git -c checkout.fetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
+'
+
+test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 2f9a597ec7..dc1d63669f 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
+	--fetch Z
 	--progress Z
 	--guess Z
 	--no-guess Z

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
-- 
gitgitgadget

Re: [PATCH] remote: add --set-head option to 'git remote add'

[Harald Nordgren]

> I don’t understand why you change the email subjects so often. Right now
> I had three “Wrong subject line” in my inbox with lost threading
> (webmail client) with the only way to distinguish them being that I was
> the the CC on this one.
> 
> Most of the time whole 100-email threads like patch series never change
> the subject. And to me it is easier to keep track of those “RE: [PATCH
> v5] florb: drop glorb” than if someone changes the subject to e.g.
> “Regarding memory leaks” because someone found a memory leak in a
> review. Because that was a reply to an email from two days ago, but I’ve
> been a away for a week so I think it’s a new thread about
> something else.

I got some feedback before, not from you, that subject lines should be
more varied, probably there is a golden middle that I need to find.

And I fundamentally agree with you.


Harald

Re: [PATCH v3] checkout: add --fetch to fetch remote before resolving start-point

[Ramsay Jones]

On 26/04/2026 8:24 am, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
[snip]

> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..cf2ceb4052 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -801,4 +801,72 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
>  	test_cmp_config "" --default "" branch.main2.merge
>  '
>  
> +test_expect_success 'setup upstream for --fetch tests' '
> +	git checkout main &&
> +	git init fetch_upstream &&
> +	test_commit -C fetch_upstream u_main &&
> +	git remote add fetch_upstream fetch_upstream &&
> +	git fetch fetch_upstream &&
> +	git -C fetch_upstream checkout -b fetch_new &&
> +	test_commit -C fetch_upstream u_new
> +'
> +
> +test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
> +	git checkout main &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
> +	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
> +'
> +
> +test_expect_success 'checkout --fetch <remote>/<branch> leaves other tracking branches untouched' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_target &&
> +	test_commit -C fetch_upstream u_target_pre &&
> +	git -C fetch_upstream checkout -b fetch_other &&
> +	test_commit -C fetch_upstream u_other_pre &&
> +	git fetch fetch_upstream &&
> +	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
> +	git -C fetch_upstream checkout fetch_target &&
> +	test_commit -C fetch_upstream u_target_post &&
> +	git -C fetch_upstream checkout fetch_other &&
> +	test_commit -C fetch_upstream u_other_post &&
> +	git checkout --fetch -b local_target fetch_upstream/fetch_target &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
> +	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
> +'
> +
> +test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_new2 &&
> +	test_commit -C fetch_upstream u_new2 &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
> +	git checkout --fetch -b local_from_remote fetch_upstream &&
> +	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
> +'
> +
> +test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
> +	git checkout main &&
> +	test_might_fail git branch -D bogus &&
> +	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
> +	test_must_fail git rev-parse --verify refs/heads/bogus
> +'
> +
> +test_expect_success 'checkout.fetch=true enables fetching without --fetch' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_cfg &&
> +	test_commit -C fetch_upstream u_cfg &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
> +	git -c checkout.fetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
> +'
> +
> +test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_switch &&
> +	test_commit -C fetch_upstream u_switch &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
> +	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
> +'
> +
>  test_done

Still just skimming the list, so ... ;)

I seem to have missed v2 (but I guess the config name changed in v2), but it seems
that there is still no test that confirms '--no-fetch' can countermand the config
variable (or, indeed, an earlier command-line '--fetch' etc,.).

[I would have no use for this facility (I have _never_ used git-pull for similar
reasons) since I would find it odd to 'mash' git-fetch into git-checkout/switch! :) ]

ATB,
Ramsay Jones

[PATCH v4] checkout: add --fetch to fetch remote before resolving start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

A common workflow is:

    git fetch origin
    git checkout -b new_branch origin/some-branch

The first command exists purely 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.

Teach checkout (and switch) a --fetch flag that folds the two steps
into one:

    git checkout --fetch -b new_branch origin/some-branch

When --fetch is given and <start-point> is in <remote>/<branch> form,
run "git fetch <remote> <branch>" before resolving the ref. This
narrows the fetch to the requested branch so that other
remote-tracking branches are left untouched -- many tools rely on the
stability of remote-tracking refs between explicit fetches. If
<start-point> is a bare remote name like "origin" (which resolves to
that remote's default branch), "git fetch <remote>" is run instead,
since the target branch is not known up front. Abort the checkout if
the fetch fails.

Also add a checkout.fetch config to enable this by default.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: add --fetch to fetch remote before resolving start-point
    
    Adding tests to confirm that '--no-fetch' can countermand the config.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v4
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v3:

 1:  df7b63862c ! 1:  150ccbb621 checkout: add --fetch to fetch remote before resolving start-point
     @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh
      +	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
      +'
      +
     ++test_expect_success '--no-fetch overrides checkout.fetch=true' '
     ++	git checkout main &&
     ++	git -C fetch_upstream checkout -b fetch_nofetch &&
     ++	test_commit -C fetch_upstream u_nofetch &&
     ++	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_nofetch &&
     ++	test_must_fail git -c checkout.fetch=true checkout --no-fetch \
     ++		-b local_nofetch fetch_upstream/fetch_nofetch &&
     ++	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_nofetch &&
     ++	test_must_fail git rev-parse --verify refs/heads/local_nofetch
     ++'
     ++
     ++test_expect_success '--no-fetch overrides earlier --fetch on command line' '
     ++	git checkout main &&
     ++	git -C fetch_upstream checkout -b fetch_override &&
     ++	test_commit -C fetch_upstream u_override &&
     ++	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_override &&
     ++	test_must_fail git checkout --fetch --no-fetch \
     ++		-b local_override fetch_upstream/fetch_override &&
     ++	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_override &&
     ++	test_must_fail git rev-parse --verify refs/heads/local_override
     ++'
     ++
      +test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
      +	git checkout main &&
      +	git -C fetch_upstream checkout -b fetch_switch &&


 Documentation/config/checkout.adoc |  5 ++
 Documentation/git-checkout.adoc    | 11 ++++
 Documentation/git-switch.adoc      | 11 ++++
 builtin/checkout.c                 | 50 ++++++++++++++++-
 t/t7201-co.sh                      | 90 ++++++++++++++++++++++++++++++
 t/t9902-completion.sh              |  1 +
 6 files changed, 166 insertions(+), 2 deletions(-)

diff --git a/Documentation/config/checkout.adoc b/Documentation/config/checkout.adoc
index e35d212969..c95f72b38e 100644
--- a/Documentation/config/checkout.adoc
+++ b/Documentation/config/checkout.adoc
@@ -22,6 +22,11 @@ commands or functionality in the future.
 	option in `git checkout` and `git switch`. See
 	linkgit:git-switch[1] and linkgit:git-checkout[1].
 
+`checkout.fetch`::
+	Provides the default value for the `--fetch` or `--no-fetch`
+	option in `git checkout` and `git switch`. See
+	linkgit:git-switch[1] and linkgit:git-checkout[1].
+
 `checkout.workers`::
 	The number of parallel workers to use when updating the working tree.
 	The default is one, i.e. sequential execution. If set to a value less
diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..f5cc1ced74 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -201,6 +201,17 @@ linkgit:git-config[1].
 The default behavior can be set via the `checkout.guess` configuration
 variable.
 
+`--fetch`::
+`--no-fetch`::
+	If _<start-point>_ refers to a remote-tracking branch, fetch
+	from that remote before resolving it. When _<start-point>_ is
+	in _<remote>/<branch>_ form, only that branch is updated; when
+	it is a bare remote name (e.g. `origin`), the whole remote is
+	fetched. If the fetch fails, the checkout is aborted.
++
+The default behavior can be set via the `checkout.fetch` configuration
+variable.
+
 `-l`::
 	Create the new branch's reflog; see linkgit:git-branch[1] for
 	details.
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..29743bafea 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -110,6 +110,17 @@ ambiguous but exists on the 'origin' remote. See also
 The default behavior can be set via the `checkout.guess` configuration
 variable.
 
+`--fetch`::
+`--no-fetch`::
+	If _<start-point>_ refers to a remote-tracking branch, fetch
+	from that remote before resolving it. When _<start-point>_ is
+	in _<remote>/<branch>_ form, only that branch is updated; when
+	it is a bare remote name (e.g. `origin`), the whole remote is
+	fetched. If the fetch fails, the switch is aborted.
++
+The default behavior can be set via the `checkout.fetch` configuration
+variable.
+
 `-f`::
 `--force`::
 	An alias for `--discard-changes`.
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..8d810fe2fa 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,7 +30,9 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 #include "submodule.h"
 #include "symlinks.h"
 #include "trace2.h"
@@ -61,6 +63,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -112,6 +115,36 @@ struct branch_info {
 	char *checkout;
 };
 
+static void fetch_remote_for_start_point(const char *arg)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (!arg || !*arg)
+		return;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	if (slash && slash[1])
+		strvec_push(&cmd.args, slash + 1);
+	cmd.git_cmd = 1;
+	free(remote_name);
+	if (run_command(&cmd))
+		die(_("failed to fetch start-point '%s'"), arg);
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1237,6 +1270,10 @@ 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.fetch")) {
+		opts->fetch = git_config_bool(var, value);
+		return 0;
+	}
 
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
@@ -1942,8 +1979,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
@@ -2052,6 +2094,8 @@ int cmd_checkout(int argc,
 		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
 		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
 			 N_("auto advance to the next file when selecting hunks interactively")),
+		OPT_BOOL(0, "fetch", &opts.fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
 		OPT_END()
 	};
 
@@ -2102,6 +2146,8 @@ int cmd_switch(int argc,
 			 N_("second guess 'git switch <no-such-branch>'")),
 		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
 			 N_("throw away local modifications")),
+		OPT_BOOL(0, "fetch", &opts.fetch,
+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
 		OPT_END()
 	};
 
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..731be2680a 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,94 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
+'
+
+test_expect_success 'checkout --fetch <remote>/<branch> leaves other tracking branches untouched' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_target &&
+	test_commit -C fetch_upstream u_target_pre &&
+	git -C fetch_upstream checkout -b fetch_other &&
+	test_commit -C fetch_upstream u_other_pre &&
+	git fetch fetch_upstream &&
+	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
+	git -C fetch_upstream checkout fetch_target &&
+	test_commit -C fetch_upstream u_target_post &&
+	git -C fetch_upstream checkout fetch_other &&
+	test_commit -C fetch_upstream u_other_post &&
+	git checkout --fetch -b local_target fetch_upstream/fetch_target &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
+'
+
+test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_new2 &&
+	test_commit -C fetch_upstream u_new2 &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
+	git checkout --fetch -b local_from_remote fetch_upstream &&
+	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
+'
+
+test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout.fetch=true enables fetching without --fetch' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_cfg &&
+	test_commit -C fetch_upstream u_cfg &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
+	git -c checkout.fetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
+'
+
+test_expect_success '--no-fetch overrides checkout.fetch=true' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_nofetch &&
+	test_commit -C fetch_upstream u_nofetch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_nofetch &&
+	test_must_fail git -c checkout.fetch=true checkout --no-fetch \
+		-b local_nofetch fetch_upstream/fetch_nofetch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_nofetch &&
+	test_must_fail git rev-parse --verify refs/heads/local_nofetch
+'
+
+test_expect_success '--no-fetch overrides earlier --fetch on command line' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_override &&
+	test_commit -C fetch_upstream u_override &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_override &&
+	test_must_fail git checkout --fetch --no-fetch \
+		-b local_override fetch_upstream/fetch_override &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_override &&
+	test_must_fail git rev-parse --verify refs/heads/local_override
+'
+
+test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 2f9a597ec7..dc1d63669f 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
+	--fetch Z
 	--progress Z
 	--guess Z
 	--no-guess Z

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
-- 
gitgitgadget

Re: [PATCH v4] checkout: add --fetch to fetch remote before resolving 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 origin/some-branch
>
> The first command exists purely so the second sees an up-to-date view
> of the remote.

This is only half true, isn't it?

Git is among projects that encourage forking only from a well-known
point in history (like the latest released version), not at a random
"tip of the day" commit from the upstream.

Such projects also tend to discourage people from constantly pulling
updated upstream into their unfinished topic branch, or rebase their
unfinished topic branch on top of updated upstream, only to "catch
up", and instead encourage them to make a trial merge to notice when
the base got too stale to cause eventual merge to conflict too much,
and when it happens, make such a back-merge, but otherwise keep
working on the stable base and avoid such "catching up".

And when working with such a project, what users who do the above is
forgetting is to inspect origin/master between the two steps to see
if it is a good commit to start your topic at.

> If it is forgotten, origin/some-branch points at a stale commit
> and the new local branch is created from the wrong start point.

So this part is not quite true.  What makes your topic begin at a
wrong starting point is not that you forget to fetch, but you forget
to verify what you fetched and think if it is a good starting point.

And for that verification to happen, you do not want "checkout" and
"fetch" mixed into one.

On the other hand, if you are allowed to fork at anywhere (as
opposed to a latest release), then not fetching and building on top
of slightly older codebase is not such a huge deal, as you're likely
to be making the "catch up" changes on top of your unfinished work
later anyway.

So as I already said before, I am fairly negative on this topic.  It
feels more like a knob to allow and actively encourage people to be
more sloppy than anything else.

I may have already pointed this out (but I do not remember), but
this option would not make any sense when --track is not in effect,
so instead of adding a brand new option, making it an extension to
the existing --track option might make it slightly more palatable.

Re: [PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Harald Nordgren]

I hope you had a good leave and is back with renewed energy! ☀️

> Git is among projects that encourage forking only from a well-known
> point in history (like the latest released version), not at a random
> "tip of the day" commit from the upstream.

Are you talking about the Git project that we are working on right now, or
talking about how people use Git "in the wild"?

Because how people use Git in the wild can be a bit different, and merge
conflicts arguably the worst part of collaborating with a team using Git.
In my early days as a professional coder, snubbed my toe countless times on
forgetting to pull in the latest changes, before starting to work on
something.

I respect that things work differently in a neatly ordered project like Git
itself, where you do a great work of organizing, but all other projects are
not like that. My advice to a junior developer is to pull in the latest
changes when starting and to rebase obsessively to prevent a large merge
conflict down the road.

> So instead of introducing a totally new option that can only be used
> only when "--track" is given, it might make more sense to introduce
> this as a variant of "--track", perhaps "--track=fetch,[in]direct"
> or something like that. 

> I may have already pointed this out (but I do not remember), but
> this option would not make any sense when --track is not in effect,
> so instead of adding a brand new option, making it an extension to
> the existing --track option might make it slightly more palatable.

Fair enough. You did point it out and I will give that a try!


Harald

[PATCH v5] checkout: extend --track with a "fetch" mode to refresh start-point

[Harald Nordgren via GitGitGadget]

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. 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.

Tie the new behavior to --track for that reason: extend its argument
to take a comma-separated list, where "fetch" can be combined with the
existing "direct" (default) and "inherit" modes. Examples:

    git checkout --track=fetch -b new_branch origin/some-branch
    git checkout --track=fetch,inherit -b new_branch some_local_branch
    git switch --track=fetch -c new_branch origin/some-branch

When "fetch" is requested and <start-point> is in <remote>/<branch>
form, run "git fetch <remote> <branch>" before resolving the ref. This
narrows the fetch to the requested branch so that other
remote-tracking branches are left untouched -- many tools rely on the
stability of remote-tracking refs between explicit fetches. If
<start-point> is a bare remote name like "origin" (which resolves to
that remote's default branch), "git fetch <remote>" is run instead,
since the target branch is not known up front. Abort the checkout if
the fetch fails.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: add --fetch to fetch remote before resolving start-point
    
     * Folded --fetch into --track. The standalone --fetch/--no-fetch flags
       are gone; the same behavior is now requested via --track=fetch
       (combinable as --track=fetch,inherit).
     * Removed the checkout.fetch config. Since fetching is tied to --track,
       there's no separate config knob anymore.
     * Docs reworked accordingly. --track's syntax is now
       (direct|inherit|fetch)[,...] in both git-checkout and git-switch man
       pages, with the fetch behavior described under it. The old --fetch
       and checkout.fetch sections are deleted.
     * New parser callback in checkout.c. A small parse_opt_checkout_track
       splits the comma-separated argument with string_list_split and sets
       opts->track and opts->fetch together.
     * Tests updated and trimmed. All test invocations switched from --fetch
       to --track=fetch. Dropped the checkout.fetch=true and --no-fetch
       override tests (those features no longer exist). Added a
       --track=fetch,inherit test, a --track=bogus error test, and stronger
       config-assertion checks on the basic test. Two redundant tests
       (fetch,direct and order-insensitivity) were removed.
     * Completion list cleaned up. --fetch removed from the expected git
       checkout option list.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v5
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v5
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v4:

 1:  150ccbb621 ! 1:  8ebc2f94b9 checkout: add --fetch to fetch remote before resolving start-point
     @@ Metadata
      Author: Harald Nordgren <haraldnordgren@gmail.com>
      
       ## Commit message ##
     -    checkout: add --fetch to fetch remote before resolving start-point
     +    checkout: extend --track with a "fetch" mode to refresh start-point
      
          A common workflow is:
      
              git fetch origin
     -        git checkout -b new_branch origin/some-branch
     +        git checkout -b new_branch --track origin/some-branch
      
     -    The first command exists purely 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.
     +    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. 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.
      
     -    Teach checkout (and switch) a --fetch flag that folds the two steps
     -    into one:
     +    Tie the new behavior to --track for that reason: extend its argument
     +    to take a comma-separated list, where "fetch" can be combined with the
     +    existing "direct" (default) and "inherit" modes. Examples:
      
     -        git checkout --fetch -b new_branch origin/some-branch
     +        git checkout --track=fetch -b new_branch origin/some-branch
     +        git checkout --track=fetch,inherit -b new_branch some_local_branch
     +        git switch --track=fetch -c new_branch origin/some-branch
      
     -    When --fetch is given and <start-point> is in <remote>/<branch> form,
     -    run "git fetch <remote> <branch>" before resolving the ref. This
     +    When "fetch" is requested and <start-point> is in <remote>/<branch>
     +    form, run "git fetch <remote> <branch>" before resolving the ref. This
          narrows the fetch to the requested branch so that other
          remote-tracking branches are left untouched -- many tools rely on the
          stability of remote-tracking refs between explicit fetches. If
     @@ Commit message
          since the target branch is not known up front. Abort the checkout if
          the fetch fails.
      
     -    Also add a checkout.fetch config to enable this by default.
     -
          Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
      
     - ## Documentation/config/checkout.adoc ##
     -@@ Documentation/config/checkout.adoc: commands or functionality in the future.
     - 	option in `git checkout` and `git switch`. See
     - 	linkgit:git-switch[1] and linkgit:git-checkout[1].
     - 
     -+`checkout.fetch`::
     -+	Provides the default value for the `--fetch` or `--no-fetch`
     -+	option in `git checkout` and `git switch`. See
     -+	linkgit:git-switch[1] and linkgit:git-checkout[1].
     -+
     - `checkout.workers`::
     - 	The number of parallel workers to use when updating the working tree.
     - 	The default is one, i.e. sequential execution. If set to a value less
     -
       ## Documentation/git-checkout.adoc ##
     -@@ Documentation/git-checkout.adoc: linkgit:git-config[1].
     - The default behavior can be set via the `checkout.guess` configuration
     - variable.
     +@@ Documentation/git-checkout.adoc: of it").
     + 	resets _<branch>_ to the start point instead of failing.
       
     -+`--fetch`::
     -+`--no-fetch`::
     -+	If _<start-point>_ refers to a remote-tracking branch, fetch
     -+	from that remote before resolving it. When _<start-point>_ is
     -+	in _<remote>/<branch>_ form, only that branch is updated; when
     -+	it is a bare remote name (e.g. `origin`), the whole remote is
     -+	fetched. If the fetch fails, the checkout is aborted.
     + `-t`::
     +-`--track[=(direct|inherit)]`::
     ++`--track[=(direct|inherit|fetch)[,...]]`::
     + 	When creating a new branch, set up "upstream" configuration. See
     + 	`--track` in linkgit:git-branch[1] for details. As a convenience,
     + 	--track without -b implies branch creation.
     + +
     ++The argument is a comma-separated list. `direct` (the default) and
     ++`inherit` select the tracking mode. Adding `fetch` requests that the
     ++remote be fetched before _<start-point>_ is resolved, so the new branch
     ++starts from a fresh tip: when _<start-point>_ is in
     ++_<remote>/<branch>_ form, only that branch is updated; when it is a
     ++bare remote name (e.g. `origin`), the whole remote is fetched. If the
     ++fetch fails, the checkout is aborted.
      ++
     -+The default behavior can be set via the `checkout.fetch` configuration
     -+variable.
     -+
     - `-l`::
     - 	Create the new branch's reflog; see linkgit:git-branch[1] for
     - 	details.
     + If no `-b` option is given, the name of the new branch will be
     + derived from the remote-tracking branch, by looking at the local part of
     + the refspec configured for the corresponding remote, and then stripping
      
       ## Documentation/git-switch.adoc ##
     -@@ Documentation/git-switch.adoc: ambiguous but exists on the 'origin' remote. See also
     - The default behavior can be set via the `checkout.guess` configuration
     - variable.
     +@@ Documentation/git-switch.adoc: should result in deletion of the path).
     + 	attached to a terminal, regardless of `--quiet`.
       
     -+`--fetch`::
     -+`--no-fetch`::
     -+	If _<start-point>_ refers to a remote-tracking branch, fetch
     -+	from that remote before resolving it. When _<start-point>_ is
     -+	in _<remote>/<branch>_ form, only that branch is updated; when
     -+	it is a bare remote name (e.g. `origin`), the whole remote is
     -+	fetched. If the fetch fails, the switch is aborted.
     + `-t`::
     +-`--track[ (direct|inherit)]`::
     ++`--track[=(direct|inherit|fetch)[,...]]`::
     + 	When creating a new branch, set up "upstream" configuration.
     + 	`-c` is implied. See `--track` in linkgit:git-branch[1] for
     + 	details.
     + +
     ++The argument is a comma-separated list. `direct` (the default) and
     ++`inherit` select the tracking mode. Adding `fetch` requests that the
     ++remote be fetched before _<start-point>_ is resolved, so the new branch
     ++starts from a fresh tip: when _<start-point>_ is in
     ++_<remote>/<branch>_ form, only that branch is updated; when it is a
     ++bare remote name (e.g. `origin`), the whole remote is fetched. If the
     ++fetch fails, the switch is aborted.
      ++
     -+The default behavior can be set via the `checkout.fetch` configuration
     -+variable.
     -+
     - `-f`::
     - `--force`::
     - 	An alias for `--discard-changes`.
     + If no `-c` option is given, the name of the new branch will be derived
     + from the remote-tracking branch, by looking at the local part of the
     + refspec configured for the corresponding remote, and then stripping
      
       ## builtin/checkout.c ##
      @@
     @@ builtin/checkout.c: struct branch_info {
      +	if (run_command(&cmd))
      +		die(_("failed to fetch start-point '%s'"), arg);
      +}
     ++
     ++static int parse_opt_checkout_track(const struct option *opt,
     ++				    const char *arg, int unset)
     ++{
     ++	struct checkout_opts *opts = opt->value;
     ++	struct string_list tokens = STRING_LIST_INIT_DUP;
     ++	struct string_list_item *item;
     ++	int ret = 0;
     ++
     ++	if (unset) {
     ++		opts->track = BRANCH_TRACK_NEVER;
     ++		opts->fetch = 0;
     ++		return 0;
     ++	}
     ++
     ++	opts->track = BRANCH_TRACK_EXPLICIT;
     ++	if (!arg)
     ++		return 0;
     ++
     ++	string_list_split(&tokens, arg, ",", -1);
     ++	for_each_string_list_item(item, &tokens) {
     ++		if (!strcmp(item->string, "fetch")) {
     ++			opts->fetch = 1;
     ++		} else if (!strcmp(item->string, "direct")) {
     ++			opts->track = BRANCH_TRACK_EXPLICIT;
     ++		} else if (!strcmp(item->string, "inherit")) {
     ++			opts->track = BRANCH_TRACK_INHERIT;
     ++		} else {
     ++			ret = error(_("option `%s' expects \"%s\", \"%s\", "
     ++				      "or \"%s\""),
     ++				    "--track", "direct", "inherit", "fetch");
     ++			break;
     ++		}
     ++	}
     ++
     ++	string_list_clear(&tokens, 0);
     ++	return ret;
     ++}
      +
       static void branch_info_release(struct branch_info *info)
       {
     @@ builtin/checkout.c: static int git_checkout_config(const char *var, const char *
       		opts->dwim_new_local_branch = git_config_bool(var, value);
       		return 0;
       	}
     -+	if (!strcmp(var, "checkout.fetch")) {
     -+		opts->fetch = 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(
     + {
     + 	struct option options[] = {
     + 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
     +-		OPT_CALLBACK_F('t', "track",  &opts->track, "(direct|inherit)",
     ++		OPT_CALLBACK_F('t', "track",  opts, "(direct|inherit|fetch)[,...]",
     + 			N_("set branch tracking configuration"),
     + 			PARSE_OPT_OPTARG,
     +-			parse_opt_tracking_mode),
     ++			parse_opt_checkout_track),
     + 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
     + 			   PARSE_OPT_NOCOMPLETE),
     + 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")),
      @@ builtin/checkout.c: static int checkout_main(int argc, const char **argv, const char *prefix,
       			opts->dwim_new_local_branch &&
       			opts->track == BRANCH_TRACK_UNSPECIFIED &&
     @@ builtin/checkout.c: static int checkout_main(int argc, const char **argv, const
       		argv += n;
       		argc -= n;
       	} else if (!opts->accept_ref && opts->from_treeish) {
     -@@ builtin/checkout.c: int cmd_checkout(int argc,
     - 		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
     - 		OPT_BOOL(0, "auto-advance", &opts.auto_advance,
     - 			 N_("auto advance to the next file when selecting hunks interactively")),
     -+		OPT_BOOL(0, "fetch", &opts.fetch,
     -+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
     - 		OPT_END()
     - 	};
     - 
     -@@ builtin/checkout.c: int cmd_switch(int argc,
     - 			 N_("second guess 'git switch <no-such-branch>'")),
     - 		OPT_BOOL(0, "discard-changes", &opts.discard_changes,
     - 			 N_("throw away local modifications")),
     -+		OPT_BOOL(0, "fetch", &opts.fetch,
     -+			 N_("fetch from the remote first if <start-point> is a remote-tracking branch")),
     - 		OPT_END()
     - 	};
     - 
      
       ## t/t7201-co.sh ##
      @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
       	test_cmp_config "" --default "" branch.main2.merge
       '
       
     -+test_expect_success 'setup upstream for --fetch tests' '
     ++test_expect_success 'setup upstream for --track=fetch tests' '
      +	git checkout main &&
      +	git init fetch_upstream &&
      +	test_commit -C fetch_upstream u_main &&
     @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh
      +	test_commit -C fetch_upstream u_new
      +'
      +
     -+test_expect_success 'checkout --fetch -b picks up branch created upstream after clone' '
     ++test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' '
      +	git checkout main &&
      +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
     -+	git checkout --fetch -b local_new fetch_upstream/fetch_new &&
     -+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD
     ++	git checkout --track=fetch -b local_new fetch_upstream/fetch_new &&
     ++	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD &&
     ++	test_cmp_config fetch_upstream branch.local_new.remote &&
     ++	test_cmp_config refs/heads/fetch_new branch.local_new.merge
      +'
      +
     -+test_expect_success 'checkout --fetch <remote>/<branch> leaves other tracking branches untouched' '
     ++test_expect_success 'checkout --track=fetch <remote>/<branch> leaves other tracking branches untouched' '
      +	git checkout main &&
      +	git -C fetch_upstream checkout -b fetch_target &&
      +	test_commit -C fetch_upstream u_target_pre &&
     @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh
      +	test_commit -C fetch_upstream u_target_post &&
      +	git -C fetch_upstream checkout fetch_other &&
      +	test_commit -C fetch_upstream u_other_post &&
     -+	git checkout --fetch -b local_target fetch_upstream/fetch_target &&
     ++	git checkout --track=fetch -b local_target fetch_upstream/fetch_target &&
      +	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
      +	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
      +'
      +
     -+test_expect_success 'checkout --fetch with bare remote name fetches the remote' '
     ++test_expect_success 'checkout --track=fetch with bare remote name fetches the remote' '
      +	git checkout main &&
      +	git -C fetch_upstream checkout -b fetch_new2 &&
      +	test_commit -C fetch_upstream u_new2 &&
      +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
     -+	git checkout --fetch -b local_from_remote fetch_upstream &&
     ++	git checkout --track=fetch -b local_from_remote fetch_upstream &&
      +	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
      +'
      +
     -+test_expect_success 'checkout --fetch aborts and does not create branch on fetch failure' '
     ++test_expect_success 'checkout --track=fetch aborts and does not create branch on fetch failure' '
      +	git checkout main &&
      +	test_might_fail git branch -D bogus &&
     -+	test_must_fail git checkout --fetch -b bogus fetch_upstream/does_not_exist &&
     ++	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
      +	test_must_fail git rev-parse --verify refs/heads/bogus
      +'
      +
     -+test_expect_success 'checkout.fetch=true enables fetching without --fetch' '
     ++test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
      +	git checkout main &&
     -+	git -C fetch_upstream checkout -b fetch_cfg &&
     -+	test_commit -C fetch_upstream u_cfg &&
     -+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_cfg &&
     -+	git -c checkout.fetch=true checkout -b local_cfg fetch_upstream/fetch_cfg &&
     -+	test_cmp_rev refs/remotes/fetch_upstream/fetch_cfg HEAD
     -+'
     -+
     -+test_expect_success '--no-fetch overrides checkout.fetch=true' '
     ++	git -C fetch_upstream checkout -b fetch_inherit &&
     ++	test_commit -C fetch_upstream u_inherit &&
     ++	git fetch fetch_upstream fetch_inherit &&
     ++	git checkout -b base_inherit fetch_upstream/fetch_inherit &&
     ++	test_commit -C fetch_upstream u_inherit2 &&
      +	git checkout main &&
     -+	git -C fetch_upstream checkout -b fetch_nofetch &&
     -+	test_commit -C fetch_upstream u_nofetch &&
     -+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_nofetch &&
     -+	test_must_fail git -c checkout.fetch=true checkout --no-fetch \
     -+		-b local_nofetch fetch_upstream/fetch_nofetch &&
     -+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_nofetch &&
     -+	test_must_fail git rev-parse --verify refs/heads/local_nofetch
     ++	git checkout --track=fetch,inherit -b local_inherit base_inherit &&
     ++	test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD &&
     ++	test_cmp_config fetch_upstream branch.local_inherit.remote &&
     ++	test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge
      +'
      +
     -+test_expect_success '--no-fetch overrides earlier --fetch on command line' '
     ++test_expect_success 'checkout --track=bogus reports an error' '
      +	git checkout main &&
     -+	git -C fetch_upstream checkout -b fetch_override &&
     -+	test_commit -C fetch_upstream u_override &&
     -+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_override &&
     -+	test_must_fail git checkout --fetch --no-fetch \
     -+		-b local_override fetch_upstream/fetch_override &&
     -+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_override &&
     -+	test_must_fail git rev-parse --verify refs/heads/local_override
     ++	test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err &&
     ++	test_grep "expects" err
      +'
      +
     -+test_expect_success 'switch --fetch -c picks up branch created upstream after clone' '
     ++test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' '
      +	git checkout main &&
      +	git -C fetch_upstream checkout -b fetch_switch &&
      +	test_commit -C fetch_upstream u_switch &&
      +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
     -+	git switch --fetch -c local_switch fetch_upstream/fetch_switch &&
     ++	git switch --track=fetch -c local_switch fetch_upstream/fetch_switch &&
      +	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
      +'
      +
       test_done
     -
     - ## 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
     -+	--fetch Z
     - 	--progress Z
     - 	--guess Z
     - 	--no-guess Z


 Documentation/git-checkout.adoc | 10 +++-
 Documentation/git-switch.adoc   | 10 +++-
 builtin/checkout.c              | 85 +++++++++++++++++++++++++++++++--
 t/t7201-co.sh                   | 81 +++++++++++++++++++++++++++++++
 4 files changed, 179 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..3b8292612d 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -158,11 +158,19 @@ of it").
 	resets _<branch>_ to the start point instead of failing.
 
 `-t`::
-`--track[=(direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration. See
 	`--track` in linkgit:git-branch[1] for details. As a convenience,
 	--track without -b implies branch creation.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode. Adding `fetch` requests that the
+remote be fetched before _<start-point>_ is resolved, so the new branch
+starts from a fresh tip: when _<start-point>_ is in
+_<remote>/<branch>_ form, only that branch is updated; when it is a
+bare remote name (e.g. `origin`), the whole remote is fetched. If the
+fetch fails, the checkout is aborted.
++
 If no `-b` option is given, the name of the new branch will be
 derived from the remote-tracking branch, by looking at the local part of
 the refspec configured for the corresponding remote, and then stripping
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..35a03e8a52 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -154,11 +154,19 @@ should result in deletion of the path).
 	attached to a terminal, regardless of `--quiet`.
 
 `-t`::
-`--track[ (direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration.
 	`-c` is implied. See `--track` in linkgit:git-branch[1] for
 	details.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode. Adding `fetch` requests that the
+remote be fetched before _<start-point>_ is resolved, so the new branch
+starts from a fresh tip: when _<start-point>_ is in
+_<remote>/<branch>_ form, only that branch is updated; when it is a
+bare remote name (e.g. `origin`), the whole remote is fetched. If the
+fetch fails, the switch is aborted.
++
 If no `-c` option is given, the name of the new branch will be derived
 from the remote-tracking branch, by looking at the local part of the
 refspec configured for the corresponding remote, and then stripping
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..de4d7c00c7 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,7 +30,9 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 #include "submodule.h"
 #include "symlinks.h"
 #include "trace2.h"
@@ -61,6 +63,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -112,6 +115,74 @@ struct branch_info {
 	char *checkout;
 };
 
+static void fetch_remote_for_start_point(const char *arg)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (!arg || !*arg)
+		return;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	if (slash && slash[1])
+		strvec_push(&cmd.args, slash + 1);
+	cmd.git_cmd = 1;
+	free(remote_name);
+	if (run_command(&cmd))
+		die(_("failed to fetch start-point '%s'"), arg);
+}
+
+static int parse_opt_checkout_track(const struct option *opt,
+				    const char *arg, int unset)
+{
+	struct checkout_opts *opts = opt->value;
+	struct string_list tokens = STRING_LIST_INIT_DUP;
+	struct string_list_item *item;
+	int ret = 0;
+
+	if (unset) {
+		opts->track = BRANCH_TRACK_NEVER;
+		opts->fetch = 0;
+		return 0;
+	}
+
+	opts->track = BRANCH_TRACK_EXPLICIT;
+	if (!arg)
+		return 0;
+
+	string_list_split(&tokens, arg, ",", -1);
+	for_each_string_list_item(item, &tokens) {
+		if (!strcmp(item->string, "fetch")) {
+			opts->fetch = 1;
+		} else if (!strcmp(item->string, "direct")) {
+			opts->track = BRANCH_TRACK_EXPLICIT;
+		} else if (!strcmp(item->string, "inherit")) {
+			opts->track = BRANCH_TRACK_INHERIT;
+		} else {
+			ret = error(_("option `%s' expects \"%s\", \"%s\", "
+				      "or \"%s\""),
+				    "--track", "direct", "inherit", "fetch");
+			break;
+		}
+	}
+
+	string_list_clear(&tokens, 0);
+	return ret;
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1237,7 +1308,6 @@ static int git_checkout_config(const char *var, const char *value,
 		opts->dwim_new_local_branch = git_config_bool(var, value);
 		return 0;
 	}
-
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
 
@@ -1734,10 +1804,10 @@ static struct option *add_common_switch_branch_options(
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_CALLBACK_F('t', "track",  &opts->track, "(direct|inherit)",
+		OPT_CALLBACK_F('t', "track",  opts, "(direct|inherit|fetch)[,...]",
 			N_("set branch tracking configuration"),
 			PARSE_OPT_OPTARG,
-			parse_opt_tracking_mode),
+			parse_opt_checkout_track),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")),
@@ -1942,8 +2012,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..39236dca12 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,85 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --track=fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --track=fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD &&
+	test_cmp_config fetch_upstream branch.local_new.remote &&
+	test_cmp_config refs/heads/fetch_new branch.local_new.merge
+'
+
+test_expect_success 'checkout --track=fetch <remote>/<branch> leaves other tracking branches untouched' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_target &&
+	test_commit -C fetch_upstream u_target_pre &&
+	git -C fetch_upstream checkout -b fetch_other &&
+	test_commit -C fetch_upstream u_other_pre &&
+	git fetch fetch_upstream &&
+	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
+	git -C fetch_upstream checkout fetch_target &&
+	test_commit -C fetch_upstream u_target_post &&
+	git -C fetch_upstream checkout fetch_other &&
+	test_commit -C fetch_upstream u_other_post &&
+	git checkout --track=fetch -b local_target fetch_upstream/fetch_target &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
+'
+
+test_expect_success 'checkout --track=fetch with bare remote name fetches the remote' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_new2 &&
+	test_commit -C fetch_upstream u_new2 &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
+	git checkout --track=fetch -b local_from_remote fetch_upstream &&
+	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
+'
+
+test_expect_success 'checkout --track=fetch aborts and does not create branch on fetch failure' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit &&
+	git fetch fetch_upstream fetch_inherit &&
+	git checkout -b base_inherit fetch_upstream/fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit2 &&
+	git checkout main &&
+	git checkout --track=fetch,inherit -b local_inherit base_inherit &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD &&
+	test_cmp_config fetch_upstream branch.local_inherit.remote &&
+	test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge
+'
+
+test_expect_success 'checkout --track=bogus reports an error' '
+	git checkout main &&
+	test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err &&
+	test_grep "expects" err
+'
+
+test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --track=fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
-- 
gitgitgadget

[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] 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] 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

[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

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 v6] checkout: extend --track with a "fetch" mode to refresh start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

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 -b new_branch --track=fetch 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
the existing 'direct' (default) and 'inherit' modes via a
comma-separated list. Examples:

    git checkout -b new_branch --track=fetch,inherit some_local_branch
    git switch -c new_branch --track=fetch origin/some-branch

When "fetch" is requested and <start-point> is in <remote>/<branch>
form, run "git fetch <remote> <branch>" before resolving the ref, so
that other remote-tracking branches are left untouched. If
<start-point> is a bare remote name like "origin" (which resolves to
that remote's default branch), "git fetch <remote>" is run instead,
since the target branch is not known up front. Abort the checkout if
the fetch fails.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: add --fetch to fetch remote before resolving start-point
    
    Commit message only, no code/doc/test changes. Restructured the opening
    around the user-visible workflow before introducing '--track=fetch',
    reordered all example invocations to ' -b/-c --track[=...] ', dropped
    the "wrong/stale start-point" and "arbitrary commit" framings, and
    trimmed the over-explanation of the narrowed fetch.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v6
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v6
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v5:

 1:  8ebc2f94b9 ! 1:  1b42c648b9 checkout: extend --track with a "fetch" mode to refresh start-point
     @@ Metadata
       ## Commit message ##
          checkout: extend --track with a "fetch" mode to refresh start-point
      
     -    A common workflow is:
     +    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
     +        git fetch origin some-branch
              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. 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.
     +    Extend the "--track" option of "git checkout" and allow users to
     +    write
      
     -    Tie the new behavior to --track for that reason: extend its argument
     -    to take a comma-separated list, where "fetch" can be combined with the
     -    existing "direct" (default) and "inherit" modes. Examples:
     +        git checkout -b new_branch --track=fetch origin/some-branch
      
     -        git checkout --track=fetch -b new_branch origin/some-branch
     -        git checkout --track=fetch,inherit -b new_branch some_local_branch
     -        git switch --track=fetch -c 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
     +    the existing 'direct' (default) and 'inherit' modes via a
     +    comma-separated list. Examples:
     +
     +        git checkout -b new_branch --track=fetch,inherit some_local_branch
     +        git switch -c new_branch --track=fetch origin/some-branch
      
          When "fetch" is requested and <start-point> is in <remote>/<branch>
     -    form, run "git fetch <remote> <branch>" before resolving the ref. This
     -    narrows the fetch to the requested branch so that other
     -    remote-tracking branches are left untouched -- many tools rely on the
     -    stability of remote-tracking refs between explicit fetches. If
     +    form, run "git fetch <remote> <branch>" before resolving the ref, so
     +    that other remote-tracking branches are left untouched. If
          <start-point> is a bare remote name like "origin" (which resolves to
          that remote's default branch), "git fetch <remote>" is run instead,
          since the target branch is not known up front. Abort the checkout if


 Documentation/git-checkout.adoc | 10 +++-
 Documentation/git-switch.adoc   | 10 +++-
 builtin/checkout.c              | 85 +++++++++++++++++++++++++++++++--
 t/t7201-co.sh                   | 81 +++++++++++++++++++++++++++++++
 4 files changed, 179 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..3b8292612d 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -158,11 +158,19 @@ of it").
 	resets _<branch>_ to the start point instead of failing.
 
 `-t`::
-`--track[=(direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration. See
 	`--track` in linkgit:git-branch[1] for details. As a convenience,
 	--track without -b implies branch creation.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode. Adding `fetch` requests that the
+remote be fetched before _<start-point>_ is resolved, so the new branch
+starts from a fresh tip: when _<start-point>_ is in
+_<remote>/<branch>_ form, only that branch is updated; when it is a
+bare remote name (e.g. `origin`), the whole remote is fetched. If the
+fetch fails, the checkout is aborted.
++
 If no `-b` option is given, the name of the new branch will be
 derived from the remote-tracking branch, by looking at the local part of
 the refspec configured for the corresponding remote, and then stripping
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..35a03e8a52 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -154,11 +154,19 @@ should result in deletion of the path).
 	attached to a terminal, regardless of `--quiet`.
 
 `-t`::
-`--track[ (direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration.
 	`-c` is implied. See `--track` in linkgit:git-branch[1] for
 	details.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode. Adding `fetch` requests that the
+remote be fetched before _<start-point>_ is resolved, so the new branch
+starts from a fresh tip: when _<start-point>_ is in
+_<remote>/<branch>_ form, only that branch is updated; when it is a
+bare remote name (e.g. `origin`), the whole remote is fetched. If the
+fetch fails, the switch is aborted.
++
 If no `-c` option is given, the name of the new branch will be derived
 from the remote-tracking branch, by looking at the local part of the
 refspec configured for the corresponding remote, and then stripping
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..de4d7c00c7 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -30,7 +30,9 @@
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 #include "submodule.h"
 #include "symlinks.h"
 #include "trace2.h"
@@ -61,6 +63,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -112,6 +115,74 @@ struct branch_info {
 	char *checkout;
 };
 
+static void fetch_remote_for_start_point(const char *arg)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (!arg || !*arg)
+		return;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	if (slash && slash[1])
+		strvec_push(&cmd.args, slash + 1);
+	cmd.git_cmd = 1;
+	free(remote_name);
+	if (run_command(&cmd))
+		die(_("failed to fetch start-point '%s'"), arg);
+}
+
+static int parse_opt_checkout_track(const struct option *opt,
+				    const char *arg, int unset)
+{
+	struct checkout_opts *opts = opt->value;
+	struct string_list tokens = STRING_LIST_INIT_DUP;
+	struct string_list_item *item;
+	int ret = 0;
+
+	if (unset) {
+		opts->track = BRANCH_TRACK_NEVER;
+		opts->fetch = 0;
+		return 0;
+	}
+
+	opts->track = BRANCH_TRACK_EXPLICIT;
+	if (!arg)
+		return 0;
+
+	string_list_split(&tokens, arg, ",", -1);
+	for_each_string_list_item(item, &tokens) {
+		if (!strcmp(item->string, "fetch")) {
+			opts->fetch = 1;
+		} else if (!strcmp(item->string, "direct")) {
+			opts->track = BRANCH_TRACK_EXPLICIT;
+		} else if (!strcmp(item->string, "inherit")) {
+			opts->track = BRANCH_TRACK_INHERIT;
+		} else {
+			ret = error(_("option `%s' expects \"%s\", \"%s\", "
+				      "or \"%s\""),
+				    "--track", "direct", "inherit", "fetch");
+			break;
+		}
+	}
+
+	string_list_clear(&tokens, 0);
+	return ret;
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1237,7 +1308,6 @@ static int git_checkout_config(const char *var, const char *value,
 		opts->dwim_new_local_branch = git_config_bool(var, value);
 		return 0;
 	}
-
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
 
@@ -1734,10 +1804,10 @@ static struct option *add_common_switch_branch_options(
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_CALLBACK_F('t', "track",  &opts->track, "(direct|inherit)",
+		OPT_CALLBACK_F('t', "track",  opts, "(direct|inherit|fetch)[,...]",
 			N_("set branch tracking configuration"),
 			PARSE_OPT_OPTARG,
-			parse_opt_tracking_mode),
+			parse_opt_checkout_track),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")),
@@ -1942,8 +2012,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..39236dca12 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,85 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --track=fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --track=fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD &&
+	test_cmp_config fetch_upstream branch.local_new.remote &&
+	test_cmp_config refs/heads/fetch_new branch.local_new.merge
+'
+
+test_expect_success 'checkout --track=fetch <remote>/<branch> leaves other tracking branches untouched' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_target &&
+	test_commit -C fetch_upstream u_target_pre &&
+	git -C fetch_upstream checkout -b fetch_other &&
+	test_commit -C fetch_upstream u_other_pre &&
+	git fetch fetch_upstream &&
+	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
+	git -C fetch_upstream checkout fetch_target &&
+	test_commit -C fetch_upstream u_target_post &&
+	git -C fetch_upstream checkout fetch_other &&
+	test_commit -C fetch_upstream u_other_post &&
+	git checkout --track=fetch -b local_target fetch_upstream/fetch_target &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
+'
+
+test_expect_success 'checkout --track=fetch with bare remote name fetches the remote' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_new2 &&
+	test_commit -C fetch_upstream u_new2 &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
+	git checkout --track=fetch -b local_from_remote fetch_upstream &&
+	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
+'
+
+test_expect_success 'checkout --track=fetch aborts and does not create branch on fetch failure' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit &&
+	git fetch fetch_upstream fetch_inherit &&
+	git checkout -b base_inherit fetch_upstream/fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit2 &&
+	git checkout main &&
+	git checkout --track=fetch,inherit -b local_inherit base_inherit &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD &&
+	test_cmp_config fetch_upstream branch.local_inherit.remote &&
+	test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge
+'
+
+test_expect_success 'checkout --track=bogus reports an error' '
+	git checkout main &&
+	test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err &&
+	test_grep "expects" err
+'
+
+test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --track=fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
-- 
gitgitgadget

[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

[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

[PATCH v6] checkout: extend --track with a "fetch" mode to refresh start-point

[Harald Nordgren]

Is this ready to move to next?


Harald

Re: [PATCH v6] checkout: extend --track with a "fetch" mode to refresh start-point

[Phillip Wood]

Hi Harald

On 07/05/2026 21:12, Harald Nordgren wrote:
> Is this ready to move to next?

I'm not particularly enthusiastic one way or the other about adding 
this, but so long as we only try to fetch when the user explicitly asks 
for it I don't particularly object. However having had a quick scan of 
the implementation I have a few comments

* "--track=inherit,direct" is nonsense and should be rejected

* currently "--track" has "last one wins" behavior so
   "--track=inherit --track=direct" behaves like "--track=direct". We
   should probably keep that so that "--track=fetch --track=direct"
   behaves like "--track=direct", not "--track=fetch,direct"

* if "git fetch" fails and the remote tracking ref already exists then
   we should print a warning and carry on rather than dying which is more
   convenient if the user or remote server are offline.

* "git checkout --track=fetch origin/branch" should respect
   remote.origin.fetch so that we fetch the ref that we're going to
   checkout. I wonder if we can share this logic with the code that
   sets the upstream branch.

* "git checkout --track=fetch origin" should only fetch the remote
   ref that we're going to checkout, not all the refs from origin. i.e.
   it should read origin/HEAD to work out what to fetch.

Thanks

Phillip

[PATCH] checkout: add --fetch to fetch remote before resolving start-point

[Harald Nordgren]

> * "--track=inherit,direct" is nonsense and should be rejected
> 
> * currently "--track" has "last one wins" behavior so
>   "--track=inherit --track=direct" behaves like "--track=direct". We
>   should probably keep that so that "--track=fetch --track=direct"
>   behaves like "--track=direct", not "--track=fetch,direct"
> 
> * if "git fetch" fails and the remote tracking ref already exists then
>   we should print a warning and carry on rather than dying which is more
>   convenient if the user or remote server are offline.
> 
> * "git checkout --track=fetch origin/branch" should respect
>   remote.origin.fetch so that we fetch the ref that we're going to
>   checkout. I wonder if we can share this logic with the code that
>   sets the upstream branch.
> 
> * "git checkout --track=fetch origin" should only fetch the remote
>   ref that we're going to checkout, not all the refs from origin. i.e.
>   it should read origin/HEAD to work out what to fetch.

Good points!


Harald

[PATCH v7] checkout: extend --track with a "fetch" mode to refresh start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

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 -b new_branch --track=fetch 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
the existing 'direct' (default) and 'inherit' modes via a
comma-separated list. Examples:

    git checkout -b new_branch --track=fetch,inherit some_local_branch
    git switch -c new_branch --track=fetch origin/some-branch

When "fetch" is requested and <start-point> is in <remote>/<branch>
form, run "git fetch <remote> <branch>" before resolving the ref, so
that other remote-tracking branches are left untouched. If
<start-point> is a bare remote name like "origin" (which resolves to
that remote's default branch), "git fetch <remote>" is run instead,
since the target branch is not known up front. Abort the checkout if
the fetch fails.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: add --fetch to fetch remote before resolving start-point
    
     * Reject --track=inherit,direct as mutually exclusive modes.
     * Make repeated --track= last-one-wins: --track=fetch --track=direct
       behaves like --track=direct.
     * On fetch failure, warn and proceed from the existing remote-tracking
       ref instead of aborting (friendlier when offline); only abort when
       there is no existing ref.
     * For --track=fetch <remote>/<branch>, resolve the source ref through
       the configured remote.<name>.fetch refspec so custom refspecs fetch
       the correct ref.
     * For --track=fetch <remote>, read <remote>/HEAD and fetch only that
       branch instead of the whole remote.
     * Tests and docs updated accordingly.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v7
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v7
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v6:

 1:  1b42c648b9 ! 1:  de375d55f1 checkout: extend --track with a "fetch" mode to refresh start-point
     @@ Documentation/git-checkout.adoc: of it").
       	--track without -b implies branch creation.
       +
      +The argument is a comma-separated list. `direct` (the default) and
     -+`inherit` select the tracking mode. Adding `fetch` requests that the
     -+remote be fetched before _<start-point>_ is resolved, so the new branch
     -+starts from a fresh tip: when _<start-point>_ is in
     -+_<remote>/<branch>_ form, only that branch is updated; when it is a
     -+bare remote name (e.g. `origin`), the whole remote is fetched. If the
     -+fetch fails, the checkout is aborted.
     ++`inherit` select the tracking mode and are mutually exclusive. Adding
     ++`fetch` requests that the remote be fetched before _<start-point>_ is
     ++resolved, so the new branch starts from a fresh tip: when
     ++_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
     ++updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
     ++only the remote's default branch is updated. If the fetch fails and the
     ++corresponding remote-tracking ref already exists, a warning is printed
     ++and the checkout proceeds from the existing tip; otherwise the checkout
     ++is aborted.
      ++
       If no `-b` option is given, the name of the new branch will be
       derived from the remote-tracking branch, by looking at the local part of
     @@ Documentation/git-switch.adoc: should result in deletion of the path).
       	details.
       +
      +The argument is a comma-separated list. `direct` (the default) and
     -+`inherit` select the tracking mode. Adding `fetch` requests that the
     -+remote be fetched before _<start-point>_ is resolved, so the new branch
     -+starts from a fresh tip: when _<start-point>_ is in
     -+_<remote>/<branch>_ form, only that branch is updated; when it is a
     -+bare remote name (e.g. `origin`), the whole remote is fetched. If the
     -+fetch fails, the switch is aborted.
     ++`inherit` select the tracking mode and are mutually exclusive. Adding
     ++`fetch` requests that the remote be fetched before _<start-point>_ is
     ++resolved, so the new branch starts from a fresh tip: when
     ++_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
     ++updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
     ++only the remote's default branch is updated. If the fetch fails and the
     ++corresponding remote-tracking ref already exists, a warning is printed
     ++and the switch proceeds from the existing tip; otherwise the switch is
     ++aborted.
      ++
       If no `-c` option is given, the name of the new branch will be derived
       from the remote-tracking branch, by looking at the local part of the
     @@ Documentation/git-switch.adoc: should result in deletion of the path).
      
       ## builtin/checkout.c ##
      @@
     + #include "preload-index.h"
     + #include "read-cache.h"
     + #include "refs.h"
     ++#include "refspec.h"
     + #include "remote.h"
       #include "repo-settings.h"
       #include "resolve-undo.h"
       #include "revision.h"
     @@ builtin/checkout.c: struct branch_info {
       	char *checkout;
       };
       
     -+static void fetch_remote_for_start_point(const char *arg)
     ++static int resolve_fetch_target(const char *arg, char **remote_out,
     ++				char **src_ref_out)
      +{
      +	const char *slash;
      +	char *remote_name;
      +	struct remote *remote;
     -+	struct child_process cmd = CHILD_PROCESS_INIT;
     ++	struct refspec_item query = { 0 };
     ++	struct strbuf dst = STRBUF_INIT;
     ++	const char *rest;
     ++
     ++	*remote_out = NULL;
     ++	*src_ref_out = NULL;
      +
      +	if (!arg || !*arg)
     -+		return;
     ++		return -1;
      +
      +	slash = strchr(arg, '/');
      +	if (slash == arg)
     -+		return;
     ++		return -1;
      +	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
      +
      +	remote = remote_get(remote_name);
      +	if (!remote || !remote_is_configured(remote, 1)) {
      +		free(remote_name);
     ++		return -1;
     ++	}
     ++
     ++	rest = (slash && slash[1]) ? slash + 1 : NULL;
     ++	if (!rest) {
     ++		struct object_id oid;
     ++		const char *head_target;
     ++		const char *short_target;
     ++
     ++		strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name);
     ++		head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
     ++						      dst.buf,
     ++						      RESOLVE_REF_READING |
     ++						      RESOLVE_REF_NO_RECURSE,
     ++						      &oid, NULL);
     ++		strbuf_reset(&dst);
     ++		if (head_target &&
     ++		    skip_prefix(head_target, "refs/remotes/", &short_target) &&
     ++		    skip_prefix(short_target, remote_name, &short_target) &&
     ++		    *short_target == '/')
     ++			rest = short_target + 1;
     ++	}
     ++
     ++	if (rest) {
     ++		strbuf_addf(&dst, "refs/remotes/%s/%s", remote_name, rest);
     ++		query.dst = dst.buf;
     ++		if (!remote_find_tracking(remote, &query) && query.src) {
     ++			*src_ref_out = xstrdup(query.src);
     ++			free(query.src);
     ++		} else {
     ++			*src_ref_out = xstrdup(rest);
     ++		}
     ++	}
     ++
     ++	strbuf_release(&dst);
     ++	*remote_out = remote_name;
     ++	return 0;
     ++}
     ++
     ++static void fetch_remote_for_start_point(const char *arg)
     ++{
     ++	char *remote_name = NULL;
     ++	char *src_ref = NULL;
     ++	struct child_process cmd = CHILD_PROCESS_INIT;
     ++	struct strbuf dst_ref = STRBUF_INIT;
     ++	int have_existing_ref = 0;
     ++
     ++	if (resolve_fetch_target(arg, &remote_name, &src_ref))
      +		return;
     ++
     ++	if (src_ref) {
     ++		const char *short_src = src_ref;
     ++		struct object_id oid;
     ++
     ++		skip_prefix(short_src, "refs/heads/", &short_src);
     ++		strbuf_addf(&dst_ref, "refs/remotes/%s/%s", remote_name, short_src);
     ++		if (!refs_read_ref(get_main_ref_store(the_repository),
     ++				   dst_ref.buf, &oid))
     ++			have_existing_ref = 1;
      +	}
      +
      +	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
     -+	if (slash && slash[1])
     -+		strvec_push(&cmd.args, slash + 1);
     ++	if (src_ref)
     ++		strvec_push(&cmd.args, src_ref);
      +	cmd.git_cmd = 1;
     ++	if (run_command(&cmd)) {
     ++		if (have_existing_ref)
     ++			warning(_("failed to fetch start-point '%s'; "
     ++				  "using existing '%s'"),
     ++				arg, dst_ref.buf);
     ++		else
     ++			die(_("failed to fetch start-point '%s'"), arg);
     ++	}
     ++
      +	free(remote_name);
     -+	if (run_command(&cmd))
     -+		die(_("failed to fetch start-point '%s'"), arg);
     ++	free(src_ref);
     ++	strbuf_release(&dst_ref);
      +}
      +
      +static int parse_opt_checkout_track(const struct option *opt,
     @@ builtin/checkout.c: struct branch_info {
      +	struct checkout_opts *opts = opt->value;
      +	struct string_list tokens = STRING_LIST_INIT_DUP;
      +	struct string_list_item *item;
     ++	int saw_direct = 0, saw_inherit = 0;
      +	int ret = 0;
      +
     ++	opts->fetch = 0;
     ++
      +	if (unset) {
      +		opts->track = BRANCH_TRACK_NEVER;
     -+		opts->fetch = 0;
      +		return 0;
      +	}
      +
     @@ builtin/checkout.c: struct branch_info {
      +		if (!strcmp(item->string, "fetch")) {
      +			opts->fetch = 1;
      +		} else if (!strcmp(item->string, "direct")) {
     ++			saw_direct = 1;
      +			opts->track = BRANCH_TRACK_EXPLICIT;
      +		} else if (!strcmp(item->string, "inherit")) {
     ++			saw_inherit = 1;
      +			opts->track = BRANCH_TRACK_INHERIT;
      +		} else {
      +			ret = error(_("option `%s' expects \"%s\", \"%s\", "
      +				      "or \"%s\""),
      +				    "--track", "direct", "inherit", "fetch");
     -+			break;
     ++			goto out;
      +		}
      +	}
      +
     ++	if (saw_direct && saw_inherit)
     ++		ret = error(_("option `%s' cannot combine \"%s\" and \"%s\""),
     ++			    "--track", "direct", "inherit");
     ++
     ++out:
      +	string_list_clear(&tokens, 0);
      +	return ret;
      +}
     @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh
      +	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
      +'
      +
     -+test_expect_success 'checkout --track=fetch with bare remote name fetches the remote' '
     ++test_expect_success 'checkout --track=fetch with bare remote name fetches only <remote>/HEAD target' '
      +	git checkout main &&
     -+	git -C fetch_upstream checkout -b fetch_new2 &&
     -+	test_commit -C fetch_upstream u_new2 &&
     -+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2 &&
     ++	git -C fetch_upstream checkout main &&
     ++	git remote set-head fetch_upstream main &&
     ++	git -C fetch_upstream checkout -b fetch_unrelated &&
     ++	test_commit -C fetch_upstream u_unrelated_pre &&
     ++	git fetch fetch_upstream fetch_unrelated &&
     ++	unrelated_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated) &&
     ++	git -C fetch_upstream checkout main &&
     ++	test_commit -C fetch_upstream u_main_post &&
     ++	git -C fetch_upstream checkout fetch_unrelated &&
     ++	test_commit -C fetch_upstream u_unrelated_post &&
      +	git checkout --track=fetch -b local_from_remote fetch_upstream &&
     -+	git rev-parse --verify refs/remotes/fetch_upstream/fetch_new2
     ++	test_cmp_rev refs/remotes/fetch_upstream/main HEAD &&
     ++	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated)" = "$unrelated_before"
      +'
      +
     -+test_expect_success 'checkout --track=fetch aborts and does not create branch on fetch failure' '
     ++test_expect_success 'checkout --track=fetch aborts and does not create branch when no existing ref' '
      +	git checkout main &&
      +	test_might_fail git branch -D bogus &&
      +	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
      +	test_must_fail git rev-parse --verify refs/heads/bogus
      +'
      +
     ++test_expect_success 'checkout --track=fetch warns and proceeds when fetch fails but ref exists' '
     ++	git checkout main &&
     ++	git -C fetch_upstream checkout -b fetch_offline &&
     ++	test_commit -C fetch_upstream u_offline &&
     ++	git fetch fetch_upstream fetch_offline &&
     ++	saved_url=$(git config remote.fetch_upstream.url) &&
     ++	test_when_finished "git config remote.fetch_upstream.url \"$saved_url\"" &&
     ++	git config remote.fetch_upstream.url ./does-not-exist &&
     ++	git checkout --track=fetch -b local_offline fetch_upstream/fetch_offline 2>err &&
     ++	test_grep "failed to fetch" err &&
     ++	test_cmp_rev refs/remotes/fetch_upstream/fetch_offline HEAD
     ++'
     ++
     ++test_expect_success 'checkout --track=fetch resolves through configured fetch refspec' '
     ++	git checkout main &&
     ++	git -C fetch_upstream checkout -b fetch_refspec &&
     ++	test_commit -C fetch_upstream u_refspec &&
     ++	git fetch fetch_upstream fetch_refspec &&
     ++	git remote add fetch_custom ./fetch_upstream &&
     ++	test_when_finished "git remote remove fetch_custom" &&
     ++	git config --replace-all remote.fetch_custom.fetch \
     ++		"+refs/heads/*:refs/remotes/custom-ns/*" &&
     ++	git fetch fetch_custom &&
     ++	test_commit -C fetch_upstream u_refspec_post &&
     ++	git checkout --track=fetch -b local_refspec custom-ns/fetch_refspec &&
     ++	test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD
     ++'
     ++
     ++test_expect_success 'checkout --track=inherit,direct is rejected' '
     ++	test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err &&
     ++	test_grep "cannot combine" err
     ++'
     ++
     ++test_expect_success 'checkout --track=fetch then --track=direct drops fetch (last-one-wins)' '
     ++	git checkout main &&
     ++	git -C fetch_upstream checkout -b fetch_lastwin &&
     ++	test_commit -C fetch_upstream u_lastwin &&
     ++	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin &&
     ++	test_must_fail git checkout --track=fetch --track=direct \
     ++		-b local_lastwin fetch_upstream/fetch_lastwin &&
     ++	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin
     ++'
     ++
      +test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
      +	git checkout main &&
      +	git -C fetch_upstream checkout -b fetch_inherit &&


 Documentation/git-checkout.adoc |  13 ++-
 Documentation/git-switch.adoc   |  13 ++-
 builtin/checkout.c              | 168 +++++++++++++++++++++++++++++++-
 t/t7201-co.sh                   | 132 +++++++++++++++++++++++++
 4 files changed, 319 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..28f17f427e 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -158,11 +158,22 @@ of it").
 	resets _<branch>_ to the start point instead of failing.
 
 `-t`::
-`--track[=(direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration. See
 	`--track` in linkgit:git-branch[1] for details. As a convenience,
 	--track without -b implies branch creation.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode and are mutually exclusive. Adding
+`fetch` requests that the remote be fetched before _<start-point>_ is
+resolved, so the new branch starts from a fresh tip: when
+_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
+updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
+only the remote's default branch is updated. If the fetch fails and the
+corresponding remote-tracking ref already exists, a warning is printed
+and the checkout proceeds from the existing tip; otherwise the checkout
+is aborted.
++
 If no `-b` option is given, the name of the new branch will be
 derived from the remote-tracking branch, by looking at the local part of
 the refspec configured for the corresponding remote, and then stripping
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..3f54cf39e9 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -154,11 +154,22 @@ should result in deletion of the path).
 	attached to a terminal, regardless of `--quiet`.
 
 `-t`::
-`--track[ (direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration.
 	`-c` is implied. See `--track` in linkgit:git-branch[1] for
 	details.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode and are mutually exclusive. Adding
+`fetch` requests that the remote be fetched before _<start-point>_ is
+resolved, so the new branch starts from a fresh tip: when
+_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
+updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
+only the remote's default branch is updated. If the fetch fails and the
+corresponding remote-tracking ref already exists, a warning is printed
+and the switch proceeds from the existing tip; otherwise the switch is
+aborted.
++
 If no `-c` option is given, the name of the new branch will be derived
 from the remote-tracking branch, by looking at the local part of the
 refspec configured for the corresponding remote, and then stripping
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e031e61886..8f8d1ecffe 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -26,11 +26,14 @@
 #include "preload-index.h"
 #include "read-cache.h"
 #include "refs.h"
+#include "refspec.h"
 #include "remote.h"
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 #include "submodule.h"
 #include "symlinks.h"
 #include "trace2.h"
@@ -61,6 +64,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -112,6 +116,156 @@ struct branch_info {
 	char *checkout;
 };
 
+static int resolve_fetch_target(const char *arg, char **remote_out,
+				char **src_ref_out)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct refspec_item query = { 0 };
+	struct strbuf dst = STRBUF_INIT;
+	const char *rest;
+
+	*remote_out = NULL;
+	*src_ref_out = NULL;
+
+	if (!arg || !*arg)
+		return -1;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return -1;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return -1;
+	}
+
+	rest = (slash && slash[1]) ? slash + 1 : NULL;
+	if (!rest) {
+		struct object_id oid;
+		const char *head_target;
+		const char *short_target;
+
+		strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name);
+		head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
+						      dst.buf,
+						      RESOLVE_REF_READING |
+						      RESOLVE_REF_NO_RECURSE,
+						      &oid, NULL);
+		strbuf_reset(&dst);
+		if (head_target &&
+		    skip_prefix(head_target, "refs/remotes/", &short_target) &&
+		    skip_prefix(short_target, remote_name, &short_target) &&
+		    *short_target == '/')
+			rest = short_target + 1;
+	}
+
+	if (rest) {
+		strbuf_addf(&dst, "refs/remotes/%s/%s", remote_name, rest);
+		query.dst = dst.buf;
+		if (!remote_find_tracking(remote, &query) && query.src) {
+			*src_ref_out = xstrdup(query.src);
+			free(query.src);
+		} else {
+			*src_ref_out = xstrdup(rest);
+		}
+	}
+
+	strbuf_release(&dst);
+	*remote_out = remote_name;
+	return 0;
+}
+
+static void fetch_remote_for_start_point(const char *arg)
+{
+	char *remote_name = NULL;
+	char *src_ref = NULL;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct strbuf dst_ref = STRBUF_INIT;
+	int have_existing_ref = 0;
+
+	if (resolve_fetch_target(arg, &remote_name, &src_ref))
+		return;
+
+	if (src_ref) {
+		const char *short_src = src_ref;
+		struct object_id oid;
+
+		skip_prefix(short_src, "refs/heads/", &short_src);
+		strbuf_addf(&dst_ref, "refs/remotes/%s/%s", remote_name, short_src);
+		if (!refs_read_ref(get_main_ref_store(the_repository),
+				   dst_ref.buf, &oid))
+			have_existing_ref = 1;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	if (src_ref)
+		strvec_push(&cmd.args, src_ref);
+	cmd.git_cmd = 1;
+	if (run_command(&cmd)) {
+		if (have_existing_ref)
+			warning(_("failed to fetch start-point '%s'; "
+				  "using existing '%s'"),
+				arg, dst_ref.buf);
+		else
+			die(_("failed to fetch start-point '%s'"), arg);
+	}
+
+	free(remote_name);
+	free(src_ref);
+	strbuf_release(&dst_ref);
+}
+
+static int parse_opt_checkout_track(const struct option *opt,
+				    const char *arg, int unset)
+{
+	struct checkout_opts *opts = opt->value;
+	struct string_list tokens = STRING_LIST_INIT_DUP;
+	struct string_list_item *item;
+	int saw_direct = 0, saw_inherit = 0;
+	int ret = 0;
+
+	opts->fetch = 0;
+
+	if (unset) {
+		opts->track = BRANCH_TRACK_NEVER;
+		return 0;
+	}
+
+	opts->track = BRANCH_TRACK_EXPLICIT;
+	if (!arg)
+		return 0;
+
+	string_list_split(&tokens, arg, ",", -1);
+	for_each_string_list_item(item, &tokens) {
+		if (!strcmp(item->string, "fetch")) {
+			opts->fetch = 1;
+		} else if (!strcmp(item->string, "direct")) {
+			saw_direct = 1;
+			opts->track = BRANCH_TRACK_EXPLICIT;
+		} else if (!strcmp(item->string, "inherit")) {
+			saw_inherit = 1;
+			opts->track = BRANCH_TRACK_INHERIT;
+		} else {
+			ret = error(_("option `%s' expects \"%s\", \"%s\", "
+				      "or \"%s\""),
+				    "--track", "direct", "inherit", "fetch");
+			goto out;
+		}
+	}
+
+	if (saw_direct && saw_inherit)
+		ret = error(_("option `%s' cannot combine \"%s\" and \"%s\""),
+			    "--track", "direct", "inherit");
+
+out:
+	string_list_clear(&tokens, 0);
+	return ret;
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1237,7 +1391,6 @@ static int git_checkout_config(const char *var, const char *value,
 		opts->dwim_new_local_branch = git_config_bool(var, value);
 		return 0;
 	}
-
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
 
@@ -1734,10 +1887,10 @@ static struct option *add_common_switch_branch_options(
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_CALLBACK_F('t', "track",  &opts->track, "(direct|inherit)",
+		OPT_CALLBACK_F('t', "track",  opts, "(direct|inherit|fetch)[,...]",
 			N_("set branch tracking configuration"),
 			PARSE_OPT_OPTARG,
-			parse_opt_tracking_mode),
+			parse_opt_checkout_track),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")),
@@ -1942,8 +2095,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..19ac6a1a2e 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,136 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --track=fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --track=fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD &&
+	test_cmp_config fetch_upstream branch.local_new.remote &&
+	test_cmp_config refs/heads/fetch_new branch.local_new.merge
+'
+
+test_expect_success 'checkout --track=fetch <remote>/<branch> leaves other tracking branches untouched' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_target &&
+	test_commit -C fetch_upstream u_target_pre &&
+	git -C fetch_upstream checkout -b fetch_other &&
+	test_commit -C fetch_upstream u_other_pre &&
+	git fetch fetch_upstream &&
+	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
+	git -C fetch_upstream checkout fetch_target &&
+	test_commit -C fetch_upstream u_target_post &&
+	git -C fetch_upstream checkout fetch_other &&
+	test_commit -C fetch_upstream u_other_post &&
+	git checkout --track=fetch -b local_target fetch_upstream/fetch_target &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
+'
+
+test_expect_success 'checkout --track=fetch with bare remote name fetches only <remote>/HEAD target' '
+	git checkout main &&
+	git -C fetch_upstream checkout main &&
+	git remote set-head fetch_upstream main &&
+	git -C fetch_upstream checkout -b fetch_unrelated &&
+	test_commit -C fetch_upstream u_unrelated_pre &&
+	git fetch fetch_upstream fetch_unrelated &&
+	unrelated_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated) &&
+	git -C fetch_upstream checkout main &&
+	test_commit -C fetch_upstream u_main_post &&
+	git -C fetch_upstream checkout fetch_unrelated &&
+	test_commit -C fetch_upstream u_unrelated_post &&
+	git checkout --track=fetch -b local_from_remote fetch_upstream &&
+	test_cmp_rev refs/remotes/fetch_upstream/main HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated)" = "$unrelated_before"
+'
+
+test_expect_success 'checkout --track=fetch aborts and does not create branch when no existing ref' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout --track=fetch warns and proceeds when fetch fails but ref exists' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_offline &&
+	test_commit -C fetch_upstream u_offline &&
+	git fetch fetch_upstream fetch_offline &&
+	saved_url=$(git config remote.fetch_upstream.url) &&
+	test_when_finished "git config remote.fetch_upstream.url \"$saved_url\"" &&
+	git config remote.fetch_upstream.url ./does-not-exist &&
+	git checkout --track=fetch -b local_offline fetch_upstream/fetch_offline 2>err &&
+	test_grep "failed to fetch" err &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_offline HEAD
+'
+
+test_expect_success 'checkout --track=fetch resolves through configured fetch refspec' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_refspec &&
+	test_commit -C fetch_upstream u_refspec &&
+	git fetch fetch_upstream fetch_refspec &&
+	git remote add fetch_custom ./fetch_upstream &&
+	test_when_finished "git remote remove fetch_custom" &&
+	git config --replace-all remote.fetch_custom.fetch \
+		"+refs/heads/*:refs/remotes/custom-ns/*" &&
+	git fetch fetch_custom &&
+	test_commit -C fetch_upstream u_refspec_post &&
+	git checkout --track=fetch -b local_refspec custom-ns/fetch_refspec &&
+	test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD
+'
+
+test_expect_success 'checkout --track=inherit,direct is rejected' '
+	test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err &&
+	test_grep "cannot combine" err
+'
+
+test_expect_success 'checkout --track=fetch then --track=direct drops fetch (last-one-wins)' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_lastwin &&
+	test_commit -C fetch_upstream u_lastwin &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin &&
+	test_must_fail git checkout --track=fetch --track=direct \
+		-b local_lastwin fetch_upstream/fetch_lastwin &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin
+'
+
+test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit &&
+	git fetch fetch_upstream fetch_inherit &&
+	git checkout -b base_inherit fetch_upstream/fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit2 &&
+	git checkout main &&
+	git checkout --track=fetch,inherit -b local_inherit base_inherit &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD &&
+	test_cmp_config fetch_upstream branch.local_inherit.remote &&
+	test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge
+'
+
+test_expect_success 'checkout --track=bogus reports an error' '
+	git checkout main &&
+	test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err &&
+	test_grep "expects" err
+'
+
+test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --track=fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0
-- 
gitgitgadget

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".

Re: [PATCH v7] checkout: extend --track with a "fetch" mode to refresh start-point

[Phillip Wood]

Hi Harald

On 08/05/2026 23:52, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> +static void fetch_remote_for_start_point(const char *arg)
> +{
> +	char *remote_name = NULL;
> +	char *src_ref = NULL;
> +	struct child_process cmd = CHILD_PROCESS_INIT;
> +	struct strbuf dst_ref = STRBUF_INIT;
> +	int have_existing_ref = 0;
> +
> +	if (resolve_fetch_target(arg, &remote_name, &src_ref))
> +		return;
> +
> +	if (src_ref) {
> +		const char *short_src = src_ref;
> +		struct object_id oid;
> +
> +		skip_prefix(short_src, "refs/heads/", &short_src);
> +		strbuf_addf(&dst_ref, "refs/remotes/%s/%s", remote_name, short_src);
> +		if (!refs_read_ref(get_main_ref_store(the_repository),
> +				   dst_ref.buf, &oid))
> +			have_existing_ref = 1;

src_ref is the name of the branch on the remote server, not the name of 
the remote tracking ref which is given by arg. If arg is a remote name 
then we need to resolve refs/remotes/$arg/HEAD to find the branch to 
check, otherwise we should be checking refs/remotes/$arg

I've only given this version a quick scan through, but I didn't notice 
any other issues.

Thanks

Phillip

> +	}
> +
> +	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
> +	if (src_ref)
> +		strvec_push(&cmd.args, src_ref);
> +	cmd.git_cmd = 1;
> +	if (run_command(&cmd)) {
> +		if (have_existing_ref)
> +			warning(_("failed to fetch start-point '%s'; "
> +				  "using existing '%s'"),
> +				arg, dst_ref.buf);
> +		else
> +			die(_("failed to fetch start-point '%s'"), arg);
> +	}
> +
> +	free(remote_name);
> +	free(src_ref);
> +	strbuf_release(&dst_ref);
> +}
> +
> +static int parse_opt_checkout_track(const struct option *opt,
> +				    const char *arg, int unset)
> +{
> +	struct checkout_opts *opts = opt->value;
> +	struct string_list tokens = STRING_LIST_INIT_DUP;
> +	struct string_list_item *item;
> +	int saw_direct = 0, saw_inherit = 0;
> +	int ret = 0;
> +
> +	opts->fetch = 0;
> +
> +	if (unset) {
> +		opts->track = BRANCH_TRACK_NEVER;
> +		return 0;
> +	}
> +
> +	opts->track = BRANCH_TRACK_EXPLICIT;
> +	if (!arg)
> +		return 0;
> +
> +	string_list_split(&tokens, arg, ",", -1);
> +	for_each_string_list_item(item, &tokens) {
> +		if (!strcmp(item->string, "fetch")) {
> +			opts->fetch = 1;
> +		} else if (!strcmp(item->string, "direct")) {
> +			saw_direct = 1;
> +			opts->track = BRANCH_TRACK_EXPLICIT;
> +		} else if (!strcmp(item->string, "inherit")) {
> +			saw_inherit = 1;
> +			opts->track = BRANCH_TRACK_INHERIT;
> +		} else {
> +			ret = error(_("option `%s' expects \"%s\", \"%s\", "
> +				      "or \"%s\""),
> +				    "--track", "direct", "inherit", "fetch");
> +			goto out;
> +		}
> +	}
> +
> +	if (saw_direct && saw_inherit)
> +		ret = error(_("option `%s' cannot combine \"%s\" and \"%s\""),
> +			    "--track", "direct", "inherit");
> +
> +out:
> +	string_list_clear(&tokens, 0);
> +	return ret;
> +}
> +
>   static void branch_info_release(struct branch_info *info)
>   {
>   	free(info->name);
> @@ -1237,7 +1391,6 @@ static int git_checkout_config(const char *var, const char *value,
>   		opts->dwim_new_local_branch = git_config_bool(var, value);
>   		return 0;
>   	}
> -
>   	if (starts_with(var, "submodule."))
>   		return git_default_submodule_config(var, value, NULL);
>   
> @@ -1734,10 +1887,10 @@ static struct option *add_common_switch_branch_options(
>   {
>   	struct option options[] = {
>   		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
> -		OPT_CALLBACK_F('t', "track",  &opts->track, "(direct|inherit)",
> +		OPT_CALLBACK_F('t', "track",  opts, "(direct|inherit|fetch)[,...]",
>   			N_("set branch tracking configuration"),
>   			PARSE_OPT_OPTARG,
> -			parse_opt_tracking_mode),
> +			parse_opt_checkout_track),
>   		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
>   			   PARSE_OPT_NOCOMPLETE),
>   		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")),
> @@ -1942,8 +2095,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
>   			opts->dwim_new_local_branch &&
>   			opts->track == BRANCH_TRACK_UNSPECIFIED &&
>   			!opts->new_branch;
> -		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
> -					     &new_branch_info, opts, &rev);
> +		int n;
> +
> +		if (opts->fetch)
> +			fetch_remote_for_start_point(argv[0]);
> +
> +		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
> +					 &new_branch_info, opts, &rev);
>   		argv += n;
>   		argc -= n;
>   	} else if (!opts->accept_ref && opts->from_treeish) {
> diff --git a/t/t7201-co.sh b/t/t7201-co.sh
> index 9bcf7c0b40..19ac6a1a2e 100755
> --- a/t/t7201-co.sh
> +++ b/t/t7201-co.sh
> @@ -801,4 +801,136 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
>   	test_cmp_config "" --default "" branch.main2.merge
>   '
>   
> +test_expect_success 'setup upstream for --track=fetch tests' '
> +	git checkout main &&
> +	git init fetch_upstream &&
> +	test_commit -C fetch_upstream u_main &&
> +	git remote add fetch_upstream fetch_upstream &&
> +	git fetch fetch_upstream &&
> +	git -C fetch_upstream checkout -b fetch_new &&
> +	test_commit -C fetch_upstream u_new
> +'
> +
> +test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' '
> +	git checkout main &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
> +	git checkout --track=fetch -b local_new fetch_upstream/fetch_new &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD &&
> +	test_cmp_config fetch_upstream branch.local_new.remote &&
> +	test_cmp_config refs/heads/fetch_new branch.local_new.merge
> +'
> +
> +test_expect_success 'checkout --track=fetch <remote>/<branch> leaves other tracking branches untouched' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_target &&
> +	test_commit -C fetch_upstream u_target_pre &&
> +	git -C fetch_upstream checkout -b fetch_other &&
> +	test_commit -C fetch_upstream u_other_pre &&
> +	git fetch fetch_upstream &&
> +	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
> +	git -C fetch_upstream checkout fetch_target &&
> +	test_commit -C fetch_upstream u_target_post &&
> +	git -C fetch_upstream checkout fetch_other &&
> +	test_commit -C fetch_upstream u_other_post &&
> +	git checkout --track=fetch -b local_target fetch_upstream/fetch_target &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
> +	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
> +'
> +
> +test_expect_success 'checkout --track=fetch with bare remote name fetches only <remote>/HEAD target' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout main &&
> +	git remote set-head fetch_upstream main &&
> +	git -C fetch_upstream checkout -b fetch_unrelated &&
> +	test_commit -C fetch_upstream u_unrelated_pre &&
> +	git fetch fetch_upstream fetch_unrelated &&
> +	unrelated_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated) &&
> +	git -C fetch_upstream checkout main &&
> +	test_commit -C fetch_upstream u_main_post &&
> +	git -C fetch_upstream checkout fetch_unrelated &&
> +	test_commit -C fetch_upstream u_unrelated_post &&
> +	git checkout --track=fetch -b local_from_remote fetch_upstream &&
> +	test_cmp_rev refs/remotes/fetch_upstream/main HEAD &&
> +	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated)" = "$unrelated_before"
> +'
> +
> +test_expect_success 'checkout --track=fetch aborts and does not create branch when no existing ref' '
> +	git checkout main &&
> +	test_might_fail git branch -D bogus &&
> +	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
> +	test_must_fail git rev-parse --verify refs/heads/bogus
> +'
> +
> +test_expect_success 'checkout --track=fetch warns and proceeds when fetch fails but ref exists' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_offline &&
> +	test_commit -C fetch_upstream u_offline &&
> +	git fetch fetch_upstream fetch_offline &&
> +	saved_url=$(git config remote.fetch_upstream.url) &&
> +	test_when_finished "git config remote.fetch_upstream.url \"$saved_url\"" &&
> +	git config remote.fetch_upstream.url ./does-not-exist &&
> +	git checkout --track=fetch -b local_offline fetch_upstream/fetch_offline 2>err &&
> +	test_grep "failed to fetch" err &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_offline HEAD
> +'
> +
> +test_expect_success 'checkout --track=fetch resolves through configured fetch refspec' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_refspec &&
> +	test_commit -C fetch_upstream u_refspec &&
> +	git fetch fetch_upstream fetch_refspec &&
> +	git remote add fetch_custom ./fetch_upstream &&
> +	test_when_finished "git remote remove fetch_custom" &&
> +	git config --replace-all remote.fetch_custom.fetch \
> +		"+refs/heads/*:refs/remotes/custom-ns/*" &&
> +	git fetch fetch_custom &&
> +	test_commit -C fetch_upstream u_refspec_post &&
> +	git checkout --track=fetch -b local_refspec custom-ns/fetch_refspec &&
> +	test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD
> +'
> +
> +test_expect_success 'checkout --track=inherit,direct is rejected' '
> +	test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err &&
> +	test_grep "cannot combine" err
> +'
> +
> +test_expect_success 'checkout --track=fetch then --track=direct drops fetch (last-one-wins)' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_lastwin &&
> +	test_commit -C fetch_upstream u_lastwin &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin &&
> +	test_must_fail git checkout --track=fetch --track=direct \
> +		-b local_lastwin fetch_upstream/fetch_lastwin &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin
> +'
> +
> +test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_inherit &&
> +	test_commit -C fetch_upstream u_inherit &&
> +	git fetch fetch_upstream fetch_inherit &&
> +	git checkout -b base_inherit fetch_upstream/fetch_inherit &&
> +	test_commit -C fetch_upstream u_inherit2 &&
> +	git checkout main &&
> +	git checkout --track=fetch,inherit -b local_inherit base_inherit &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD &&
> +	test_cmp_config fetch_upstream branch.local_inherit.remote &&
> +	test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge
> +'
> +
> +test_expect_success 'checkout --track=bogus reports an error' '
> +	git checkout main &&
> +	test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err &&
> +	test_grep "expects" err
> +'
> +
> +test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' '
> +	git checkout main &&
> +	git -C fetch_upstream checkout -b fetch_switch &&
> +	test_commit -C fetch_upstream u_switch &&
> +	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
> +	git switch --track=fetch -c local_switch fetch_upstream/fetch_switch &&
> +	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
> +'
> +
>   test_done
> 
> base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0

[PATCH v8] checkout: extend --track with a "fetch" mode to refresh start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

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 -b new_branch --track=fetch 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
the existing 'direct' (default) and 'inherit' modes via a
comma-separated list. Examples:

    git checkout -b new_branch --track=fetch,inherit some_local_branch
    git switch -c new_branch --track=fetch origin/some-branch

When "fetch" is requested and <start-point> is in <remote>/<branch>
form, run "git fetch <remote> <branch>" before resolving the ref, so
that other remote-tracking branches are left untouched. If
<start-point> is a bare remote name like "origin" (which resolves to
that remote's default branch), "git fetch <remote>" is run instead,
since the target branch is not known up front. Abort the checkout if
the fetch fails.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: --track=fetch
    
    Check the fallback ref using arg directly instead of reconstructing it.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v8
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v8
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v7:

 1:  de375d55f1 ! 1:  61c2199fd5 checkout: extend --track with a "fetch" mode to refresh start-point
     @@ builtin/checkout.c
       #include "revision.h"
      +#include "run-command.h"
       #include "setup.h"
     -+#include "strvec.h"
     + #include "strvec.h"
       #include "submodule.h"
     - #include "symlinks.h"
     - #include "trace2.h"
      @@ builtin/checkout.c: struct checkout_opts {
       	int count_checkout_paths;
       	int overlay_mode;
     @@ builtin/checkout.c: struct branch_info {
      +	if (resolve_fetch_target(arg, &remote_name, &src_ref))
      +		return;
      +
     -+	if (src_ref) {
     -+		const char *short_src = src_ref;
     ++	{
      +		struct object_id oid;
      +
     -+		skip_prefix(short_src, "refs/heads/", &short_src);
     -+		strbuf_addf(&dst_ref, "refs/remotes/%s/%s", remote_name, short_src);
     ++		if (strchr(arg, '/'))
     ++			strbuf_addf(&dst_ref, "refs/remotes/%s", arg);
     ++		else
     ++			strbuf_addf(&dst_ref, "refs/remotes/%s/HEAD", arg);
      +		if (!refs_read_ref(get_main_ref_store(the_repository),
      +				   dst_ref.buf, &oid))
      +			have_existing_ref = 1;


 Documentation/git-checkout.adoc |  13 ++-
 Documentation/git-switch.adoc   |  13 ++-
 builtin/checkout.c              | 168 +++++++++++++++++++++++++++++++-
 t/t7201-co.sh                   | 132 +++++++++++++++++++++++++
 4 files changed, 319 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..28f17f427e 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -158,11 +158,22 @@ of it").
 	resets _<branch>_ to the start point instead of failing.
 
 `-t`::
-`--track[=(direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration. See
 	`--track` in linkgit:git-branch[1] for details. As a convenience,
 	--track without -b implies branch creation.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode and are mutually exclusive. Adding
+`fetch` requests that the remote be fetched before _<start-point>_ is
+resolved, so the new branch starts from a fresh tip: when
+_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
+updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
+only the remote's default branch is updated. If the fetch fails and the
+corresponding remote-tracking ref already exists, a warning is printed
+and the checkout proceeds from the existing tip; otherwise the checkout
+is aborted.
++
 If no `-b` option is given, the name of the new branch will be
 derived from the remote-tracking branch, by looking at the local part of
 the refspec configured for the corresponding remote, and then stripping
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..3f54cf39e9 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -154,11 +154,22 @@ should result in deletion of the path).
 	attached to a terminal, regardless of `--quiet`.
 
 `-t`::
-`--track[ (direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration.
 	`-c` is implied. See `--track` in linkgit:git-branch[1] for
 	details.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode and are mutually exclusive. Adding
+`fetch` requests that the remote be fetched before _<start-point>_ is
+resolved, so the new branch starts from a fresh tip: when
+_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
+updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
+only the remote's default branch is updated. If the fetch fails and the
+corresponding remote-tracking ref already exists, a warning is printed
+and the switch proceeds from the existing tip; otherwise the switch is
+aborted.
++
 If no `-c` option is given, the name of the new branch will be derived
 from the remote-tracking branch, by looking at the local part of the
 refspec configured for the corresponding remote, and then stripping
diff --git a/builtin/checkout.c b/builtin/checkout.c
index ac0186a33e..157242bc9f 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -26,10 +26,12 @@
 #include "preload-index.h"
 #include "read-cache.h"
 #include "refs.h"
+#include "refspec.h"
 #include "remote.h"
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
 #include "strvec.h"
 #include "submodule.h"
@@ -62,6 +64,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -113,6 +116,157 @@ struct branch_info {
 	char *checkout;
 };
 
+static int resolve_fetch_target(const char *arg, char **remote_out,
+				char **src_ref_out)
+{
+	const char *slash;
+	char *remote_name;
+	struct remote *remote;
+	struct refspec_item query = { 0 };
+	struct strbuf dst = STRBUF_INIT;
+	const char *rest;
+
+	*remote_out = NULL;
+	*src_ref_out = NULL;
+
+	if (!arg || !*arg)
+		return -1;
+
+	slash = strchr(arg, '/');
+	if (slash == arg)
+		return -1;
+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
+
+	remote = remote_get(remote_name);
+	if (!remote || !remote_is_configured(remote, 1)) {
+		free(remote_name);
+		return -1;
+	}
+
+	rest = (slash && slash[1]) ? slash + 1 : NULL;
+	if (!rest) {
+		struct object_id oid;
+		const char *head_target;
+		const char *short_target;
+
+		strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name);
+		head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
+						      dst.buf,
+						      RESOLVE_REF_READING |
+						      RESOLVE_REF_NO_RECURSE,
+						      &oid, NULL);
+		strbuf_reset(&dst);
+		if (head_target &&
+		    skip_prefix(head_target, "refs/remotes/", &short_target) &&
+		    skip_prefix(short_target, remote_name, &short_target) &&
+		    *short_target == '/')
+			rest = short_target + 1;
+	}
+
+	if (rest) {
+		strbuf_addf(&dst, "refs/remotes/%s/%s", remote_name, rest);
+		query.dst = dst.buf;
+		if (!remote_find_tracking(remote, &query) && query.src) {
+			*src_ref_out = xstrdup(query.src);
+			free(query.src);
+		} else {
+			*src_ref_out = xstrdup(rest);
+		}
+	}
+
+	strbuf_release(&dst);
+	*remote_out = remote_name;
+	return 0;
+}
+
+static void fetch_remote_for_start_point(const char *arg)
+{
+	char *remote_name = NULL;
+	char *src_ref = NULL;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct strbuf dst_ref = STRBUF_INIT;
+	int have_existing_ref = 0;
+
+	if (resolve_fetch_target(arg, &remote_name, &src_ref))
+		return;
+
+	{
+		struct object_id oid;
+
+		if (strchr(arg, '/'))
+			strbuf_addf(&dst_ref, "refs/remotes/%s", arg);
+		else
+			strbuf_addf(&dst_ref, "refs/remotes/%s/HEAD", arg);
+		if (!refs_read_ref(get_main_ref_store(the_repository),
+				   dst_ref.buf, &oid))
+			have_existing_ref = 1;
+	}
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	if (src_ref)
+		strvec_push(&cmd.args, src_ref);
+	cmd.git_cmd = 1;
+	if (run_command(&cmd)) {
+		if (have_existing_ref)
+			warning(_("failed to fetch start-point '%s'; "
+				  "using existing '%s'"),
+				arg, dst_ref.buf);
+		else
+			die(_("failed to fetch start-point '%s'"), arg);
+	}
+
+	free(remote_name);
+	free(src_ref);
+	strbuf_release(&dst_ref);
+}
+
+static int parse_opt_checkout_track(const struct option *opt,
+				    const char *arg, int unset)
+{
+	struct checkout_opts *opts = opt->value;
+	struct string_list tokens = STRING_LIST_INIT_DUP;
+	struct string_list_item *item;
+	int saw_direct = 0, saw_inherit = 0;
+	int ret = 0;
+
+	opts->fetch = 0;
+
+	if (unset) {
+		opts->track = BRANCH_TRACK_NEVER;
+		return 0;
+	}
+
+	opts->track = BRANCH_TRACK_EXPLICIT;
+	if (!arg)
+		return 0;
+
+	string_list_split(&tokens, arg, ",", -1);
+	for_each_string_list_item(item, &tokens) {
+		if (!strcmp(item->string, "fetch")) {
+			opts->fetch = 1;
+		} else if (!strcmp(item->string, "direct")) {
+			saw_direct = 1;
+			opts->track = BRANCH_TRACK_EXPLICIT;
+		} else if (!strcmp(item->string, "inherit")) {
+			saw_inherit = 1;
+			opts->track = BRANCH_TRACK_INHERIT;
+		} else {
+			ret = error(_("option `%s' expects \"%s\", \"%s\", "
+				      "or \"%s\""),
+				    "--track", "direct", "inherit", "fetch");
+			goto out;
+		}
+	}
+
+	if (saw_direct && saw_inherit)
+		ret = error(_("option `%s' cannot combine \"%s\" and \"%s\""),
+			    "--track", "direct", "inherit");
+
+out:
+	string_list_clear(&tokens, 0);
+	return ret;
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1244,7 +1398,6 @@ static int git_checkout_config(const char *var, const char *value,
 		opts->dwim_new_local_branch = git_config_bool(var, value);
 		return 0;
 	}
-
 	if (starts_with(var, "submodule."))
 		return git_default_submodule_config(var, value, NULL);
 
@@ -1741,10 +1894,10 @@ static struct option *add_common_switch_branch_options(
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_CALLBACK_F('t', "track",  &opts->track, "(direct|inherit)",
+		OPT_CALLBACK_F('t', "track",  opts, "(direct|inherit|fetch)[,...]",
 			N_("set branch tracking configuration"),
 			PARSE_OPT_OPTARG,
-			parse_opt_tracking_mode),
+			parse_opt_checkout_track),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")),
@@ -1949,8 +2102,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..19ac6a1a2e 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,136 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --track=fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --track=fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD &&
+	test_cmp_config fetch_upstream branch.local_new.remote &&
+	test_cmp_config refs/heads/fetch_new branch.local_new.merge
+'
+
+test_expect_success 'checkout --track=fetch <remote>/<branch> leaves other tracking branches untouched' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_target &&
+	test_commit -C fetch_upstream u_target_pre &&
+	git -C fetch_upstream checkout -b fetch_other &&
+	test_commit -C fetch_upstream u_other_pre &&
+	git fetch fetch_upstream &&
+	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
+	git -C fetch_upstream checkout fetch_target &&
+	test_commit -C fetch_upstream u_target_post &&
+	git -C fetch_upstream checkout fetch_other &&
+	test_commit -C fetch_upstream u_other_post &&
+	git checkout --track=fetch -b local_target fetch_upstream/fetch_target &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
+'
+
+test_expect_success 'checkout --track=fetch with bare remote name fetches only <remote>/HEAD target' '
+	git checkout main &&
+	git -C fetch_upstream checkout main &&
+	git remote set-head fetch_upstream main &&
+	git -C fetch_upstream checkout -b fetch_unrelated &&
+	test_commit -C fetch_upstream u_unrelated_pre &&
+	git fetch fetch_upstream fetch_unrelated &&
+	unrelated_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated) &&
+	git -C fetch_upstream checkout main &&
+	test_commit -C fetch_upstream u_main_post &&
+	git -C fetch_upstream checkout fetch_unrelated &&
+	test_commit -C fetch_upstream u_unrelated_post &&
+	git checkout --track=fetch -b local_from_remote fetch_upstream &&
+	test_cmp_rev refs/remotes/fetch_upstream/main HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated)" = "$unrelated_before"
+'
+
+test_expect_success 'checkout --track=fetch aborts and does not create branch when no existing ref' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout --track=fetch warns and proceeds when fetch fails but ref exists' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_offline &&
+	test_commit -C fetch_upstream u_offline &&
+	git fetch fetch_upstream fetch_offline &&
+	saved_url=$(git config remote.fetch_upstream.url) &&
+	test_when_finished "git config remote.fetch_upstream.url \"$saved_url\"" &&
+	git config remote.fetch_upstream.url ./does-not-exist &&
+	git checkout --track=fetch -b local_offline fetch_upstream/fetch_offline 2>err &&
+	test_grep "failed to fetch" err &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_offline HEAD
+'
+
+test_expect_success 'checkout --track=fetch resolves through configured fetch refspec' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_refspec &&
+	test_commit -C fetch_upstream u_refspec &&
+	git fetch fetch_upstream fetch_refspec &&
+	git remote add fetch_custom ./fetch_upstream &&
+	test_when_finished "git remote remove fetch_custom" &&
+	git config --replace-all remote.fetch_custom.fetch \
+		"+refs/heads/*:refs/remotes/custom-ns/*" &&
+	git fetch fetch_custom &&
+	test_commit -C fetch_upstream u_refspec_post &&
+	git checkout --track=fetch -b local_refspec custom-ns/fetch_refspec &&
+	test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD
+'
+
+test_expect_success 'checkout --track=inherit,direct is rejected' '
+	test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err &&
+	test_grep "cannot combine" err
+'
+
+test_expect_success 'checkout --track=fetch then --track=direct drops fetch (last-one-wins)' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_lastwin &&
+	test_commit -C fetch_upstream u_lastwin &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin &&
+	test_must_fail git checkout --track=fetch --track=direct \
+		-b local_lastwin fetch_upstream/fetch_lastwin &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin
+'
+
+test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit &&
+	git fetch fetch_upstream fetch_inherit &&
+	git checkout -b base_inherit fetch_upstream/fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit2 &&
+	git checkout main &&
+	git checkout --track=fetch,inherit -b local_inherit base_inherit &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD &&
+	test_cmp_config fetch_upstream branch.local_inherit.remote &&
+	test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge
+'
+
+test_expect_success 'checkout --track=bogus reports an error' '
+	git checkout main &&
+	test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err &&
+	test_grep "expects" err
+'
+
+test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --track=fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done

base-commit: 7760f83b59750c27df653c5c46d0f80e44cfe02c
-- 
gitgitgadget

Re: [PATCH v8] checkout: extend --track with a "fetch" mode to refresh start-point

[Junio C Hamano]

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

> diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
> index 43ccf47cf6..28f17f427e 100644
> --- a/Documentation/git-checkout.adoc
> +++ b/Documentation/git-checkout.adoc
> @@ -158,11 +158,22 @@ of it").
>  	resets _<branch>_ to the start point instead of failing.
>  
>  `-t`::
> -`--track[=(direct|inherit)]`::
> +`--track[=(direct|inherit|fetch)[,...]]`::
>  	When creating a new branch, set up "upstream" configuration. See
>  	`--track` in linkgit:git-branch[1] for details. As a convenience,
>  	--track without -b implies branch creation.
>  +
> +The argument is a comma-separated list. `direct` (the default) and
> +`inherit` select the tracking mode and are mutually exclusive. Adding
> +`fetch` requests that the remote be fetched before _<start-point>_ is
> +resolved, so the new branch starts from a fresh tip: when
> +_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
> +updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
> +only the remote's default branch is updated.

The latter is because "checkout -t -b new remote/origin" makes "new"
track "remote/origin/HEAD", which makes sense.  And of course this
fetch can fail.

> +static int resolve_fetch_target(const char *arg, char **remote_out,
> +				char **src_ref_out)
> +{
> +	const char *slash;
> +	char *remote_name;
> +	struct remote *remote;
> +	struct refspec_item query = { 0 };
> +	struct strbuf dst = STRBUF_INIT;
> +	const char *rest;
> +
> +	*remote_out = NULL;
> +	*src_ref_out = NULL;
> +
> +	if (!arg || !*arg)
> +		return -1;
> +
> +	slash = strchr(arg, '/');
> +	if (slash == arg)
> +		return -1;
> +	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
> +
> +	remote = remote_get(remote_name);
> +	if (!remote || !remote_is_configured(remote, 1)) {
> +		free(remote_name);
> +		return -1;
> +	}
> +
> +	rest = (slash && slash[1]) ? slash + 1 : NULL;

There is no slash when asking for "origin", and the control goes
into the "if (!rest)" block.

> +	if (!rest) {
> +		struct object_id oid;
> +		const char *head_target;
> +		const char *short_target;
> +
> +		strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name);
> +		head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
> +						      dst.buf,
> +						      RESOLVE_REF_READING |
> +						      RESOLVE_REF_NO_RECURSE,
> +						      &oid, NULL);
> +		strbuf_reset(&dst);
> +		if (head_target &&
> +		    skip_prefix(head_target, "refs/remotes/", &short_target) &&
> +		    skip_prefix(short_target, remote_name, &short_target) &&
> +		    *short_target == '/')
> +			rest = short_target + 1;
> +	}

If refs/remotes/origin/HEAD points at refs/remotes/origin/main, rest
gets "main".  Otherwise (i.e. unexpected contents in HEAD or lacking
HEAD), rest remains NULL.  And then we have the "if (rest)" block.

> +	if (rest) {
> +		strbuf_addf(&dst, "refs/remotes/%s/%s", remote_name, rest);
> +		query.dst = dst.buf;
> +		if (!remote_find_tracking(remote, &query) && query.src) {
> +			*src_ref_out = xstrdup(query.src);
> +			free(query.src);
> +		} else {
> +			*src_ref_out = xstrdup(rest);
> +		}
> +	}
> +
> +	strbuf_release(&dst);
> +	*remote_out = remote_name;
> +	return 0;
> +}

It is not a new problem but I do not remember how we explicitly
forbid "hierarchical" remote names.  refs/remotes/a/b/c might be
their branch "b/c" at remote we call "a", or branch "c" at remote
"a/b".  Unless we forbid slashes in remote names, the "there is no
slash so we got only the name of the remote to mean its HEAD" logic
would not work well, so we may want to double check.

> +static void fetch_remote_for_start_point(const char *arg)
> +{
> +	char *remote_name = NULL;
> +	char *src_ref = NULL;
> +	struct child_process cmd = CHILD_PROCESS_INIT;
> +	struct strbuf dst_ref = STRBUF_INIT;
> +	int have_existing_ref = 0;
> +
> +	if (resolve_fetch_target(arg, &remote_name, &src_ref))
> +		return;
> +
> +	{
> +		struct object_id oid;
> +
> +		if (strchr(arg, '/'))
> +			strbuf_addf(&dst_ref, "refs/remotes/%s", arg);
> +		else
> +			strbuf_addf(&dst_ref, "refs/remotes/%s/HEAD", arg);
> +		if (!refs_read_ref(get_main_ref_store(the_repository),
> +				   dst_ref.buf, &oid))
> +			have_existing_ref = 1;
> +	}

I do not quite see the point of this extra block.  Can we do without
it (and move the def of oid up near the beginning of the function,
of course)?

Even better, as resolve_fetch_target() already looks at "arg" and
poked at the remote-tracking ref hierarchy, wouldn't it make more
sense to make that helper function responsible for finding out if
there already is a usable, albeit potentially stale, ref?  


> +	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
> +	if (src_ref)
> +		strvec_push(&cmd.args, src_ref);
> +	cmd.git_cmd = 1;
> +	if (run_command(&cmd)) {
> +		if (have_existing_ref)
> +			warning(_("failed to fetch start-point '%s'; "
> +				  "using existing '%s'"),
> +				arg, dst_ref.buf);
> +		else
> +			die(_("failed to fetch start-point '%s'"), arg);
> +	}
> +
> +	free(remote_name);
> +	free(src_ref);
> +	strbuf_release(&dst_ref);
> +}

> @@ -1244,7 +1398,6 @@ static int git_checkout_config(const char *var, const char *value,
>  		opts->dwim_new_local_branch = git_config_bool(var, value);
>  		return 0;
>  	}
> -
>  	if (starts_with(var, "submodule."))
>  		return git_default_submodule_config(var, value, NULL);

Unrelated patch noise?

[PATCH v9] checkout: extend --track with a "fetch" mode to refresh start-point

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

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 -b new_branch --track=fetch 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
the existing 'direct' (default) and 'inherit' modes via a
comma-separated list. Examples:

    git checkout -b new_branch --track=fetch,inherit some_local_branch
    git switch -c new_branch --track=fetch origin/some-branch

When "fetch" is requested and <start-point> is in <remote>/<branch>
form, run "git fetch <remote> <branch>" before resolving the ref, so
that other remote-tracking branches are left untouched. If
<start-point> is a bare remote name like "origin" (which resolves to
that remote's default branch), "git fetch <remote>" is run instead,
since the target branch is not known up front. Abort the checkout if
the fetch fails.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    checkout: --track=fetch
    
     * Support hierarchical remote names (e.g. nested/remote) by trying the
       longest prefix first.
     * Fold the existing-ref lookup into resolve_fetch_target() so it
       returns the ref name directly.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v9
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v9
Pull-Request: https://github.com/git/git/pull/2281

Range-diff vs v8:

 1:  61c2199fd5 ! 1:  021375e4cc checkout: extend --track with a "fetch" mode to refresh start-point
     @@ builtin/checkout.c: struct branch_info {
       };
       
      +static int resolve_fetch_target(const char *arg, char **remote_out,
     -+				char **src_ref_out)
     ++				char **src_ref_out, char **existing_ref_out)
      +{
      +	const char *slash;
     -+	char *remote_name;
     -+	struct remote *remote;
     ++	char *remote_name = NULL;
     ++	struct remote *remote = NULL;
      +	struct refspec_item query = { 0 };
      +	struct strbuf dst = STRBUF_INIT;
     -+	const char *rest;
     ++	struct object_id oid;
     ++	const char *rest = NULL;
     ++	const char *head_target = NULL;
     ++	const char *short_target;
      +
      +	*remote_out = NULL;
      +	*src_ref_out = NULL;
     ++	*existing_ref_out = NULL;
      +
     -+	if (!arg || !*arg)
     -+		return -1;
     -+
     -+	slash = strchr(arg, '/');
     -+	if (slash == arg)
     ++	if (!arg || !*arg || *arg == '/')
      +		return -1;
     -+	remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg);
      +
     -+	remote = remote_get(remote_name);
     -+	if (!remote || !remote_is_configured(remote, 1)) {
     ++	slash = arg + strlen(arg);
     ++	while (1) {
      +		free(remote_name);
     -+		return -1;
     ++		remote_name = xstrndup(arg, slash - arg);
     ++		remote = remote_get(remote_name);
     ++		if (remote && remote_is_configured(remote, 1))
     ++			break;
     ++		while (slash > arg && *--slash != '/')
     ++			;
     ++		if (slash == arg) {
     ++			free(remote_name);
     ++			return -1;
     ++		}
      +	}
      +
     -+	rest = (slash && slash[1]) ? slash + 1 : NULL;
     ++	if (*slash == '/' && slash[1])
     ++		rest = slash + 1;
      +	if (!rest) {
     -+		struct object_id oid;
     -+		const char *head_target;
     -+		const char *short_target;
     -+
      +		strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name);
      +		head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
      +						      dst.buf,
      +						      RESOLVE_REF_READING |
      +						      RESOLVE_REF_NO_RECURSE,
      +						      &oid, NULL);
     ++		if (head_target) {
     ++			*existing_ref_out = xstrdup(dst.buf);
     ++			if (skip_prefix(head_target, "refs/remotes/", &short_target) &&
     ++			    skip_prefix(short_target, remote_name, &short_target) &&
     ++			    *short_target == '/')
     ++				rest = short_target + 1;
     ++		}
      +		strbuf_reset(&dst);
     -+		if (head_target &&
     -+		    skip_prefix(head_target, "refs/remotes/", &short_target) &&
     -+		    skip_prefix(short_target, remote_name, &short_target) &&
     -+		    *short_target == '/')
     -+			rest = short_target + 1;
      +	}
      +
      +	if (rest) {
     @@ builtin/checkout.c: struct branch_info {
      +		} else {
      +			*src_ref_out = xstrdup(rest);
      +		}
     ++		if (!*existing_ref_out) {
     ++			strbuf_reset(&dst);
     ++			strbuf_addf(&dst, "refs/remotes/%s", arg);
     ++			if (!refs_read_ref(get_main_ref_store(the_repository),
     ++					   dst.buf, &oid))
     ++				*existing_ref_out = xstrdup(dst.buf);
     ++		}
      +	}
      +
      +	strbuf_release(&dst);
     @@ builtin/checkout.c: struct branch_info {
      +{
      +	char *remote_name = NULL;
      +	char *src_ref = NULL;
     ++	char *existing_ref = NULL;
      +	struct child_process cmd = CHILD_PROCESS_INIT;
     -+	struct strbuf dst_ref = STRBUF_INIT;
     -+	int have_existing_ref = 0;
      +
     -+	if (resolve_fetch_target(arg, &remote_name, &src_ref))
     ++	if (resolve_fetch_target(arg, &remote_name, &src_ref, &existing_ref))
      +		return;
      +
     -+	{
     -+		struct object_id oid;
     -+
     -+		if (strchr(arg, '/'))
     -+			strbuf_addf(&dst_ref, "refs/remotes/%s", arg);
     -+		else
     -+			strbuf_addf(&dst_ref, "refs/remotes/%s/HEAD", arg);
     -+		if (!refs_read_ref(get_main_ref_store(the_repository),
     -+				   dst_ref.buf, &oid))
     -+			have_existing_ref = 1;
     -+	}
     -+
      +	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
      +	if (src_ref)
      +		strvec_push(&cmd.args, src_ref);
      +	cmd.git_cmd = 1;
      +	if (run_command(&cmd)) {
     -+		if (have_existing_ref)
     ++		if (existing_ref)
      +			warning(_("failed to fetch start-point '%s'; "
      +				  "using existing '%s'"),
     -+				arg, dst_ref.buf);
     ++				arg, existing_ref);
      +		else
      +			die(_("failed to fetch start-point '%s'"), arg);
      +	}
      +
      +	free(remote_name);
      +	free(src_ref);
     -+	strbuf_release(&dst_ref);
     ++	free(existing_ref);
      +}
      +
      +static int parse_opt_checkout_track(const struct option *opt,
     @@ builtin/checkout.c: struct branch_info {
       static void branch_info_release(struct branch_info *info)
       {
       	free(info->name);
     -@@ 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 (starts_with(var, "submodule."))
     - 		return git_default_submodule_config(var, value, NULL);
     - 
      @@ builtin/checkout.c: static struct option *add_common_switch_branch_options(
       {
       	struct option options[] = {
     @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh
      +	test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD
      +'
      +
     ++test_expect_success 'checkout --track=fetch handles hierarchical remote name' '
     ++	git checkout main &&
     ++	git -C fetch_upstream checkout -b fetch_hier &&
     ++	test_commit -C fetch_upstream u_hier &&
     ++	git remote add nested/remote ./fetch_upstream &&
     ++	test_when_finished "git remote remove nested/remote" &&
     ++	git fetch nested/remote fetch_hier &&
     ++	test_commit -C fetch_upstream u_hier_post &&
     ++	git checkout --track=fetch -b local_hier nested/remote/fetch_hier &&
     ++	test_cmp_rev refs/remotes/nested/remote/fetch_hier HEAD
     ++'
     ++
      +test_expect_success 'checkout --track=inherit,direct is rejected' '
      +	test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err &&
      +	test_grep "cannot combine" err


 Documentation/git-checkout.adoc |  13 ++-
 Documentation/git-switch.adoc   |  13 ++-
 builtin/checkout.c              | 168 +++++++++++++++++++++++++++++++-
 t/t7201-co.sh                   | 144 +++++++++++++++++++++++++++
 4 files changed, 332 insertions(+), 6 deletions(-)

diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc
index 43ccf47cf6..28f17f427e 100644
--- a/Documentation/git-checkout.adoc
+++ b/Documentation/git-checkout.adoc
@@ -158,11 +158,22 @@ of it").
 	resets _<branch>_ to the start point instead of failing.
 
 `-t`::
-`--track[=(direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration. See
 	`--track` in linkgit:git-branch[1] for details. As a convenience,
 	--track without -b implies branch creation.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode and are mutually exclusive. Adding
+`fetch` requests that the remote be fetched before _<start-point>_ is
+resolved, so the new branch starts from a fresh tip: when
+_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
+updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
+only the remote's default branch is updated. If the fetch fails and the
+corresponding remote-tracking ref already exists, a warning is printed
+and the checkout proceeds from the existing tip; otherwise the checkout
+is aborted.
++
 If no `-b` option is given, the name of the new branch will be
 derived from the remote-tracking branch, by looking at the local part of
 the refspec configured for the corresponding remote, and then stripping
diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc
index 87707e9265..3f54cf39e9 100644
--- a/Documentation/git-switch.adoc
+++ b/Documentation/git-switch.adoc
@@ -154,11 +154,22 @@ should result in deletion of the path).
 	attached to a terminal, regardless of `--quiet`.
 
 `-t`::
-`--track[ (direct|inherit)]`::
+`--track[=(direct|inherit|fetch)[,...]]`::
 	When creating a new branch, set up "upstream" configuration.
 	`-c` is implied. See `--track` in linkgit:git-branch[1] for
 	details.
 +
+The argument is a comma-separated list. `direct` (the default) and
+`inherit` select the tracking mode and are mutually exclusive. Adding
+`fetch` requests that the remote be fetched before _<start-point>_ is
+resolved, so the new branch starts from a fresh tip: when
+_<start-point>_ is in _<remote>/<branch>_ form, only that branch is
+updated; when _<start-point>_ is a bare remote name (e.g. `origin`),
+only the remote's default branch is updated. If the fetch fails and the
+corresponding remote-tracking ref already exists, a warning is printed
+and the switch proceeds from the existing tip; otherwise the switch is
+aborted.
++
 If no `-c` option is given, the name of the new branch will be derived
 from the remote-tracking branch, by looking at the local part of the
 refspec configured for the corresponding remote, and then stripping
diff --git a/builtin/checkout.c b/builtin/checkout.c
index ac0186a33e..aff442c526 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -26,10 +26,12 @@
 #include "preload-index.h"
 #include "read-cache.h"
 #include "refs.h"
+#include "refspec.h"
 #include "remote.h"
 #include "repo-settings.h"
 #include "resolve-undo.h"
 #include "revision.h"
+#include "run-command.h"
 #include "setup.h"
 #include "strvec.h"
 #include "submodule.h"
@@ -62,6 +64,7 @@ struct checkout_opts {
 	int count_checkout_paths;
 	int overlay_mode;
 	int dwim_new_local_branch;
+	int fetch;
 	int discard_changes;
 	int accept_ref;
 	int accept_pathspec;
@@ -113,6 +116,158 @@ struct branch_info {
 	char *checkout;
 };
 
+static int resolve_fetch_target(const char *arg, char **remote_out,
+				char **src_ref_out, char **existing_ref_out)
+{
+	const char *slash;
+	char *remote_name = NULL;
+	struct remote *remote = NULL;
+	struct refspec_item query = { 0 };
+	struct strbuf dst = STRBUF_INIT;
+	struct object_id oid;
+	const char *rest = NULL;
+	const char *head_target = NULL;
+	const char *short_target;
+
+	*remote_out = NULL;
+	*src_ref_out = NULL;
+	*existing_ref_out = NULL;
+
+	if (!arg || !*arg || *arg == '/')
+		return -1;
+
+	slash = arg + strlen(arg);
+	while (1) {
+		free(remote_name);
+		remote_name = xstrndup(arg, slash - arg);
+		remote = remote_get(remote_name);
+		if (remote && remote_is_configured(remote, 1))
+			break;
+		while (slash > arg && *--slash != '/')
+			;
+		if (slash == arg) {
+			free(remote_name);
+			return -1;
+		}
+	}
+
+	if (*slash == '/' && slash[1])
+		rest = slash + 1;
+	if (!rest) {
+		strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name);
+		head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
+						      dst.buf,
+						      RESOLVE_REF_READING |
+						      RESOLVE_REF_NO_RECURSE,
+						      &oid, NULL);
+		if (head_target) {
+			*existing_ref_out = xstrdup(dst.buf);
+			if (skip_prefix(head_target, "refs/remotes/", &short_target) &&
+			    skip_prefix(short_target, remote_name, &short_target) &&
+			    *short_target == '/')
+				rest = short_target + 1;
+		}
+		strbuf_reset(&dst);
+	}
+
+	if (rest) {
+		strbuf_addf(&dst, "refs/remotes/%s/%s", remote_name, rest);
+		query.dst = dst.buf;
+		if (!remote_find_tracking(remote, &query) && query.src) {
+			*src_ref_out = xstrdup(query.src);
+			free(query.src);
+		} else {
+			*src_ref_out = xstrdup(rest);
+		}
+		if (!*existing_ref_out) {
+			strbuf_reset(&dst);
+			strbuf_addf(&dst, "refs/remotes/%s", arg);
+			if (!refs_read_ref(get_main_ref_store(the_repository),
+					   dst.buf, &oid))
+				*existing_ref_out = xstrdup(dst.buf);
+		}
+	}
+
+	strbuf_release(&dst);
+	*remote_out = remote_name;
+	return 0;
+}
+
+static void fetch_remote_for_start_point(const char *arg)
+{
+	char *remote_name = NULL;
+	char *src_ref = NULL;
+	char *existing_ref = NULL;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (resolve_fetch_target(arg, &remote_name, &src_ref, &existing_ref))
+		return;
+
+	strvec_pushl(&cmd.args, "fetch", remote_name, NULL);
+	if (src_ref)
+		strvec_push(&cmd.args, src_ref);
+	cmd.git_cmd = 1;
+	if (run_command(&cmd)) {
+		if (existing_ref)
+			warning(_("failed to fetch start-point '%s'; "
+				  "using existing '%s'"),
+				arg, existing_ref);
+		else
+			die(_("failed to fetch start-point '%s'"), arg);
+	}
+
+	free(remote_name);
+	free(src_ref);
+	free(existing_ref);
+}
+
+static int parse_opt_checkout_track(const struct option *opt,
+				    const char *arg, int unset)
+{
+	struct checkout_opts *opts = opt->value;
+	struct string_list tokens = STRING_LIST_INIT_DUP;
+	struct string_list_item *item;
+	int saw_direct = 0, saw_inherit = 0;
+	int ret = 0;
+
+	opts->fetch = 0;
+
+	if (unset) {
+		opts->track = BRANCH_TRACK_NEVER;
+		return 0;
+	}
+
+	opts->track = BRANCH_TRACK_EXPLICIT;
+	if (!arg)
+		return 0;
+
+	string_list_split(&tokens, arg, ",", -1);
+	for_each_string_list_item(item, &tokens) {
+		if (!strcmp(item->string, "fetch")) {
+			opts->fetch = 1;
+		} else if (!strcmp(item->string, "direct")) {
+			saw_direct = 1;
+			opts->track = BRANCH_TRACK_EXPLICIT;
+		} else if (!strcmp(item->string, "inherit")) {
+			saw_inherit = 1;
+			opts->track = BRANCH_TRACK_INHERIT;
+		} else {
+			ret = error(_("option `%s' expects \"%s\", \"%s\", "
+				      "or \"%s\""),
+				    "--track", "direct", "inherit", "fetch");
+			goto out;
+		}
+	}
+
+	if (saw_direct && saw_inherit)
+		ret = error(_("option `%s' cannot combine \"%s\" and \"%s\""),
+			    "--track", "direct", "inherit");
+
+out:
+	string_list_clear(&tokens, 0);
+	return ret;
+}
+
 static void branch_info_release(struct branch_info *info)
 {
 	free(info->name);
@@ -1741,10 +1896,10 @@ static struct option *add_common_switch_branch_options(
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_CALLBACK_F('t', "track",  &opts->track, "(direct|inherit)",
+		OPT_CALLBACK_F('t', "track",  opts, "(direct|inherit|fetch)[,...]",
 			N_("set branch tracking configuration"),
 			PARSE_OPT_OPTARG,
-			parse_opt_tracking_mode),
+			parse_opt_checkout_track),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")),
@@ -1949,8 +2104,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
 			opts->dwim_new_local_branch &&
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
-		int n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
-					     &new_branch_info, opts, &rev);
+		int n;
+
+		if (opts->fetch)
+			fetch_remote_for_start_point(argv[0]);
+
+		n = parse_branchname_arg(argc, argv, dwim_ok, which_command,
+					 &new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 9bcf7c0b40..6dfe9ec931 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -801,4 +801,148 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
 	test_cmp_config "" --default "" branch.main2.merge
 '
 
+test_expect_success 'setup upstream for --track=fetch tests' '
+	git checkout main &&
+	git init fetch_upstream &&
+	test_commit -C fetch_upstream u_main &&
+	git remote add fetch_upstream fetch_upstream &&
+	git fetch fetch_upstream &&
+	git -C fetch_upstream checkout -b fetch_new &&
+	test_commit -C fetch_upstream u_new
+'
+
+test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' '
+	git checkout main &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new &&
+	git checkout --track=fetch -b local_new fetch_upstream/fetch_new &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD &&
+	test_cmp_config fetch_upstream branch.local_new.remote &&
+	test_cmp_config refs/heads/fetch_new branch.local_new.merge
+'
+
+test_expect_success 'checkout --track=fetch <remote>/<branch> leaves other tracking branches untouched' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_target &&
+	test_commit -C fetch_upstream u_target_pre &&
+	git -C fetch_upstream checkout -b fetch_other &&
+	test_commit -C fetch_upstream u_other_pre &&
+	git fetch fetch_upstream &&
+	other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) &&
+	git -C fetch_upstream checkout fetch_target &&
+	test_commit -C fetch_upstream u_target_post &&
+	git -C fetch_upstream checkout fetch_other &&
+	test_commit -C fetch_upstream u_other_post &&
+	git checkout --track=fetch -b local_target fetch_upstream/fetch_target &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before"
+'
+
+test_expect_success 'checkout --track=fetch with bare remote name fetches only <remote>/HEAD target' '
+	git checkout main &&
+	git -C fetch_upstream checkout main &&
+	git remote set-head fetch_upstream main &&
+	git -C fetch_upstream checkout -b fetch_unrelated &&
+	test_commit -C fetch_upstream u_unrelated_pre &&
+	git fetch fetch_upstream fetch_unrelated &&
+	unrelated_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated) &&
+	git -C fetch_upstream checkout main &&
+	test_commit -C fetch_upstream u_main_post &&
+	git -C fetch_upstream checkout fetch_unrelated &&
+	test_commit -C fetch_upstream u_unrelated_post &&
+	git checkout --track=fetch -b local_from_remote fetch_upstream &&
+	test_cmp_rev refs/remotes/fetch_upstream/main HEAD &&
+	test "$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated)" = "$unrelated_before"
+'
+
+test_expect_success 'checkout --track=fetch aborts and does not create branch when no existing ref' '
+	git checkout main &&
+	test_might_fail git branch -D bogus &&
+	test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist &&
+	test_must_fail git rev-parse --verify refs/heads/bogus
+'
+
+test_expect_success 'checkout --track=fetch warns and proceeds when fetch fails but ref exists' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_offline &&
+	test_commit -C fetch_upstream u_offline &&
+	git fetch fetch_upstream fetch_offline &&
+	saved_url=$(git config remote.fetch_upstream.url) &&
+	test_when_finished "git config remote.fetch_upstream.url \"$saved_url\"" &&
+	git config remote.fetch_upstream.url ./does-not-exist &&
+	git checkout --track=fetch -b local_offline fetch_upstream/fetch_offline 2>err &&
+	test_grep "failed to fetch" err &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_offline HEAD
+'
+
+test_expect_success 'checkout --track=fetch resolves through configured fetch refspec' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_refspec &&
+	test_commit -C fetch_upstream u_refspec &&
+	git fetch fetch_upstream fetch_refspec &&
+	git remote add fetch_custom ./fetch_upstream &&
+	test_when_finished "git remote remove fetch_custom" &&
+	git config --replace-all remote.fetch_custom.fetch \
+		"+refs/heads/*:refs/remotes/custom-ns/*" &&
+	git fetch fetch_custom &&
+	test_commit -C fetch_upstream u_refspec_post &&
+	git checkout --track=fetch -b local_refspec custom-ns/fetch_refspec &&
+	test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD
+'
+
+test_expect_success 'checkout --track=fetch handles hierarchical remote name' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_hier &&
+	test_commit -C fetch_upstream u_hier &&
+	git remote add nested/remote ./fetch_upstream &&
+	test_when_finished "git remote remove nested/remote" &&
+	git fetch nested/remote fetch_hier &&
+	test_commit -C fetch_upstream u_hier_post &&
+	git checkout --track=fetch -b local_hier nested/remote/fetch_hier &&
+	test_cmp_rev refs/remotes/nested/remote/fetch_hier HEAD
+'
+
+test_expect_success 'checkout --track=inherit,direct is rejected' '
+	test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err &&
+	test_grep "cannot combine" err
+'
+
+test_expect_success 'checkout --track=fetch then --track=direct drops fetch (last-one-wins)' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_lastwin &&
+	test_commit -C fetch_upstream u_lastwin &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin &&
+	test_must_fail git checkout --track=fetch --track=direct \
+		-b local_lastwin fetch_upstream/fetch_lastwin &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin
+'
+
+test_expect_success 'checkout --track=fetch,inherit fetches and inherits' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit &&
+	git fetch fetch_upstream fetch_inherit &&
+	git checkout -b base_inherit fetch_upstream/fetch_inherit &&
+	test_commit -C fetch_upstream u_inherit2 &&
+	git checkout main &&
+	git checkout --track=fetch,inherit -b local_inherit base_inherit &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD &&
+	test_cmp_config fetch_upstream branch.local_inherit.remote &&
+	test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge
+'
+
+test_expect_success 'checkout --track=bogus reports an error' '
+	git checkout main &&
+	test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err &&
+	test_grep "expects" err
+'
+
+test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' '
+	git checkout main &&
+	git -C fetch_upstream checkout -b fetch_switch &&
+	test_commit -C fetch_upstream u_switch &&
+	test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch &&
+	git switch --track=fetch -c local_switch fetch_upstream/fetch_switch &&
+	test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD
+'
+
 test_done

base-commit: 29bd7ed5127255713c1ac2f43b7c6f257d7b4594
-- 
gitgitgadget