[PATCH 0/2] checkout -m: refine autostash fallback

[PATCH 0/2] checkout -m: refine autostash fallback

[Harald Nordgren via GitGitGadget]

Avoiding checkout -m autostash retries when no tracked local changes exist
and visually separating autostash conflict advice from the subsequent
branch-switch message.

Addresses #leftoverbits from here:
https://lore.kernel.org/git/cfd09dbf-8d77-4464-8030-3a0ffb4aeae7@gmail.com/

Harald Nordgren (2):
  sequencer: teach autostash apply to report conflicts
  checkout -m: refine autostash fallback

 builtin/checkout.c | 18 ++++++++++++++----
 builtin/commit.c   |  2 +-
 builtin/merge.c    |  6 +++---
 sequencer.c        | 29 +++++++++++++++++++----------
 sequencer.h        |  3 ++-
 t/t7201-co.sh      | 17 ++++++++++++++++-
 6 files changed, 55 insertions(+), 20 deletions(-)


base-commit: 9a0c4701dcd5725c4184599322b52933ff5005ca
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2364%2FHaraldNordgren%2Fhn%2Fgit-checkout-m-leftoverbits-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2364/HaraldNordgren/hn/git-checkout-m-leftoverbits-v1
Pull-Request: https://github.com/git/git/pull/2364
-- 
gitgitgadget

[PATCH 1/2] sequencer: teach autostash apply to report conflicts

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

Add a conflicted parameter to apply_save_autostash_oid() and
apply_save_autostash_ref() so callers can learn whether applying the
stash resulted in conflicts.  Thread the parameter through
apply_autostash_ref() and update existing callers to pass NULL.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/checkout.c |  3 ++-
 builtin/commit.c   |  2 +-
 builtin/merge.c    |  6 +++---
 sequencer.c        | 29 +++++++++++++++++++----------
 sequencer.h        |  3 ++-
 5 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index aee84ca897..72aafa4049 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1242,7 +1242,8 @@ static int switch_branches(const struct checkout_opts *opts,
 					    new_branch_info->name,
 					    "local",
 					    stash_label_base,
-					    autostash_msg.buf);
+					    autostash_msg.buf,
+					    NULL);
 		}
 		if (ret) {
 			branch_info_release(&old_branch_info);
diff --git a/builtin/commit.c b/builtin/commit.c
index 28f6174503..d678a81865 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1980,7 +1980,7 @@ int cmd_commit(int argc,
 	}
 
 	apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
-			    NULL, NULL, NULL, NULL);
+			    NULL, NULL, NULL, NULL, NULL);
 
 cleanup:
 	free_commit_extra_headers(extra);
diff --git a/builtin/merge.c b/builtin/merge.c
index 5b46a596f0..cecb8fb716 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -538,7 +538,7 @@ static void finish(struct commit *head_commit,
 
 	if (new_head)
 		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
-				    NULL, NULL, NULL, NULL);
+				    NULL, NULL, NULL, NULL, NULL);
 	strbuf_release(&reflog_message);
 }
 
@@ -1680,7 +1680,7 @@ int cmd_merge(int argc,
 					  &commit->object.oid,
 					  overwrite_ignore)) {
 			apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
-					    NULL, NULL, NULL, NULL);
+					    NULL, NULL, NULL, NULL, NULL);
 			ret = 1;
 			goto done;
 		}
@@ -1844,7 +1844,7 @@ int cmd_merge(int argc,
 			fprintf(stderr, _("Merge with strategy %s failed.\n"),
 				use_strategies[0]->name);
 		apply_autostash_ref(the_repository, "MERGE_AUTOSTASH",
-				    NULL, NULL, NULL, NULL);
+				    NULL, NULL, NULL, NULL, NULL);
 		ret = 2;
 		goto done;
 	} else if (best_strategy == wt_strategy)
diff --git a/sequencer.c b/sequencer.c
index 1355a99a09..91a70e39a1 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4748,7 +4748,8 @@ void create_autostash_ref(struct repository *r, const char *refname,
 static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 				    const char *label_ours, const char *label_theirs,
 				    const char *label_base,
-				    const char *stash_msg)
+				    const char *stash_msg,
+				    bool *conflicted)
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
@@ -4783,14 +4784,16 @@ static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply,
 		strvec_push(&store.args, stash_oid);
 		if (run_command(&store))
 			ret = error(_("cannot store %s"), stash_oid);
-		else if (attempt_apply)
+		else if (attempt_apply) {
+			if (conflicted)
+				*conflicted = true;
 			fprintf(stderr,
 				_("Your local changes are stashed, however applying them\n"
 				  "resulted in conflicts.  You can either resolve the conflicts\n"
 				  "and then discard the stash with \"git stash drop\", or, if you\n"
 				  "do not want to resolve them now, run \"git reset --hard\" and\n"
 				  "apply the local changes later by running \"git stash pop\".\n"));
-		else
+		} else
 			fprintf(stderr,
 				_("Autostash exists; creating a new stash entry.\n"
 				  "Your changes are safe in the stash.\n"
@@ -4814,7 +4817,7 @@ static int apply_save_autostash(const char *path, int attempt_apply)
 	strbuf_trim(&stash_oid);
 
 	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply,
-				      NULL, NULL, NULL, NULL);
+				      NULL, NULL, NULL, NULL, NULL);
 
 	unlink(path);
 	strbuf_release(&stash_oid);
@@ -4833,19 +4836,24 @@ int apply_autostash(const char *path)
 
 int apply_autostash_oid(const char *stash_oid)
 {
-	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL);
+	return apply_save_autostash_oid(stash_oid, 1, NULL, NULL, NULL, NULL,
+				       NULL);
 }
 
 static int apply_save_autostash_ref(struct repository *r, const char *refname,
 				    int attempt_apply,
 				    const char *label_ours, const char *label_theirs,
 				    const char *label_base,
-				    const char *stash_msg)
+				    const char *stash_msg,
+				    bool *conflicted)
 {
 	struct object_id stash_oid;
 	char stash_oid_hex[GIT_MAX_HEXSZ + 1];
 	int flag, ret;
 
+	if (conflicted)
+		*conflicted = false;
+
 	if (!refs_ref_exists(get_main_ref_store(r), refname))
 		return 0;
 
@@ -4858,7 +4866,7 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 	oid_to_hex_r(stash_oid_hex, &stash_oid);
 	ret = apply_save_autostash_oid(stash_oid_hex, attempt_apply,
 				       label_ours, label_theirs, label_base,
-				       stash_msg);
+				       stash_msg, conflicted);
 
 	refs_delete_ref(get_main_ref_store(r), "", refname,
 			&stash_oid, REF_NO_DEREF);
@@ -4869,16 +4877,17 @@ static int apply_save_autostash_ref(struct repository *r, const char *refname,
 int save_autostash_ref(struct repository *r, const char *refname)
 {
 	return apply_save_autostash_ref(r, refname, 0,
-					NULL, NULL, NULL, NULL);
+					NULL, NULL, NULL, NULL, NULL);
 }
 
 int apply_autostash_ref(struct repository *r, const char *refname,
 			const char *label_ours, const char *label_theirs,
-			const char *label_base, const char *stash_msg)
+			const char *label_base, const char *stash_msg,
+			bool *conflicted)
 {
 	return apply_save_autostash_ref(r, refname, 1,
 					label_ours, label_theirs, label_base,
-					stash_msg);
+					stash_msg, conflicted);
 }
 
 static int checkout_onto(struct repository *r, struct replay_opts *opts,
diff --git a/sequencer.h b/sequencer.h
index 64a9c7fb1b..b39528b6d0 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -237,7 +237,8 @@ int apply_autostash(const char *path);
 int apply_autostash_oid(const char *stash_oid);
 int apply_autostash_ref(struct repository *r, const char *refname,
 			const char *label_ours, const char *label_theirs,
-			const char *label_base, const char *stash_msg);
+			const char *label_base, const char *stash_msg,
+			bool *conflicted);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
-- 
gitgitgadget

[PATCH 2/2] checkout -m: refine autostash fallback

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

When unpack_trees() fails under "git checkout -m", only create an
autostash and retry if there are tracked local changes.  Without such
changes, the fallback cannot help and merely repeats the same failure.

Use the conflict result from apply_autostash_ref() to print a blank line
before the branch-switch message, visually separating it from the
conflict advice.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 builtin/checkout.c | 17 +++++++++++++----
 t/t7201-co.sh      | 17 ++++++++++++++++-
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 72aafa4049..2e8b2a2348 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -838,10 +838,11 @@ static void init_topts(struct unpack_trees_options *topts,
 static int merge_working_tree(const struct checkout_opts *opts,
 			      struct branch_info *old_branch_info,
 			      struct branch_info *new_branch_info,
-			      bool quiet,
+			      bool allow_autostash,
 			      int *writeout_error)
 {
 	int ret;
+	bool can_autostash = false;
 	struct lock_file lock_file = LOCK_INIT;
 	struct tree *new_tree;
 
@@ -888,9 +889,13 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			return 1;
 		}
 
+		if (allow_autostash)
+			can_autostash = has_unstaged_changes(the_repository, 1) ||
+				has_uncommitted_changes(the_repository, 1);
+
 		/* 2-way merge to the new branch */
 		init_topts(&topts, opts->show_progress,
-			   opts->overwrite_ignore, quiet);
+			   opts->overwrite_ignore, can_autostash);
 		init_checkout_metadata(&topts.meta, new_branch_info->refname,
 				       new_branch_info->commit ?
 				       &new_branch_info->commit->object.oid :
@@ -917,7 +922,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		clear_unpack_trees_porcelain(&topts);
 		if (ret == -1) {
 			rollback_lock_file(&lock_file);
-			return MERGE_WORKING_TREE_UNPACK_FAILED;
+			return can_autostash ?
+				MERGE_WORKING_TREE_UNPACK_FAILED : 1;
 		}
 	}
 
@@ -1166,6 +1172,7 @@ static int switch_branches(const struct checkout_opts *opts,
 	int flag, writeout_error = 0;
 	int do_merge = 1;
 	int created_autostash = 0;
+	bool autostash_conflicted = false;
 	struct strbuf old_commit_shortname = STRBUF_INIT;
 	struct strbuf autostash_msg = STRBUF_INIT;
 	const char *stash_label_base = NULL;
@@ -1243,7 +1250,7 @@ static int switch_branches(const struct checkout_opts *opts,
 					    "local",
 					    stash_label_base,
 					    autostash_msg.buf,
-					    NULL);
+					    &autostash_conflicted);
 		}
 		if (ret) {
 			branch_info_release(&old_branch_info);
@@ -1256,6 +1263,8 @@ static int switch_branches(const struct checkout_opts *opts,
 	if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
 		orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
 
+	if (autostash_conflicted && !opts->quiet)
+		fputc('\n', stderr);
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
 	if (created_autostash) {
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 0ddd1ad7aa..f9696dab36 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -240,6 +240,14 @@ test_expect_success 'checkout -m creates a recoverable stash on conflict' '
 	test_grep "git stash drop" actual &&
 	test_grep "git stash pop" actual &&
 	test_grep "The following paths have local changes" actual &&
+	sed -n "/apply the local changes later/,/Switched to branch/p" \
+		actual >separator.actual &&
+	cat >separator.expect <<-EOF &&
+	apply the local changes later by running "git stash pop".
+
+	Switched to branch ${SQ}side${SQ}
+	EOF
+	test_cmp separator.expect separator.actual &&
 	git log -p -1 --format="%gs%n%B" -g --diff-merges=1 refs/stash >actual &&
 	sed /^index/d actual >actual.trimmed &&
 	cat >expect <<-EOF &&
@@ -262,11 +270,18 @@ test_expect_success 'checkout -m creates a recoverable stash on conflict' '
 	git reset --hard
 '
 
-test_expect_success 'checkout -m which would overwrite untracked file' '
+test_expect_success 'checkout -m only retries untracked-file failure with local changes' '
 	git checkout -f --detach main &&
 	test_commit another-file &&
 	git checkout HEAD^ &&
 	>another-file.t &&
+	test_must_fail env GIT_TRACE2_EVENT="$(pwd)/trace" \
+		git checkout -m @{-1} 2>err &&
+	test_grep "untracked working tree files" err &&
+	grep "\"region_enter\".*\"category\":\"index\",\"label\":\"refresh\"" \
+		trace >refresh.events &&
+	test_line_count = 1 refresh.events &&
+
 	fill 1 2 3 4 5 >one &&
 	test_must_fail git checkout -m @{-1} 2>err &&
 	q_to_tab >expect <<-\EOF &&
-- 
gitgitgadget