Re: [PATCH v4 0/2] checkout -m: refine autostash fallback
From: Phillip Wood <hidden>
Date: 2026-09-03 14:00:40
Hi Harald On 02/09/2026 19:29, Harald Nordgren via GitGitGadget wrote:
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/ (local) Changes in v4: * Conflicts now exit with status 1 like merge-tree, other failures exit 128 so exit 1 unambiguously means conflicts. Stash changes split into their own commit.
Thanks for changing the exit codes, I don't have anything to add to Junio's comments. Thanks Phillip
* The autostash apply helpers use the return value (enum
stash_apply_result) instead of an out-parameter, and only claim conflicts
when git stash apply actually reported them.
Changes in v3:
* Use enum for git stash return values, to separate conflict from generic
error.
Changes in v2:
* Simplify logic and combine to one commit.
* Test full output with test_cmp.
Harald Nordgren (2):
stash: reserve exit status 1 for conflicts
checkout: separate autostash conflict advice from branch-switch
message
Documentation/git-stash.adoc | 9 +++++
builtin/checkout.c | 15 ++++----
builtin/stash.c | 32 ++++++++++++-----
sequencer.c | 66 ++++++++++++++++++++++--------------
sequencer.h | 19 +++++++----
stash.h | 21 ++++++++++++
t/t3903-stash.sh | 25 ++++++++++++--
t/t7201-co.sh | 16 ++++++---
8 files changed, 149 insertions(+), 54 deletions(-)
create mode 100644 stash.h
base-commit: 1630431f326e15fcde608827b5ff38422528eb59
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2364%2FHaraldNordgren%2Fhn%2Fgit-checkout-m-leftoverbits-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2364/HaraldNordgren/hn/git-checkout-m-leftoverbits-v4
Pull-Request: https://github.com/git/git/pull/2364
Range-diff vs v3:
1: 8e1979dd6c ! 1: ff43221802 checkout: separate autostash conflict advice from branch-switch message
@@ Metadata
Author: Harald Nordgren [off-list ref]
## Commit message ##
- checkout: separate autostash conflict advice from branch-switch message
+ stash: reserve exit status 1 for conflicts
- "git checkout -m" stashes the user's local changes when it cannot
- perform the checkout, and then applies the stash. When applying the
- stash results in conflicts, the advice on how to deal with them is
- printed directly on top of the branch-switch message ("Switched to
- branch ..."), making the two hard to tell apart. Print a blank line
- in between so that the advice and the branch-switch message are
- visually distinct.
+ "git stash apply", "pop" and "branch" exit with status 1 both when
+ applying the stash entry resulted in conflicts and when they fail for
+ other reasons, so callers cannot tell the two apart.
- To make this possible, "git stash apply", "pop" and "branch" now exit
- with status 2 when applying the stash entry resulted in conflicts, in
- which case the stash entry is left in place; other failures exit with
- status 1, as before. The exit statuses are documented in the "git
- stash" documentation.
+ Follow the convention of "git merge-tree" and the merge strategies,
+ which exit with status 1 to indicate conflicts and with a different
+ non-zero status for errors: those subcommands now exit with status 1
+ only when applying the stash entry resulted in conflicts, in which
+ case the stash entry is left in place, and exit with status 128, the
+ status die() uses, when they fail for other reasons. Document the
+ exit statuses.
+
+ cmd_stash() used to collapse the return values of the subcommand
+ implementations to a boolean. It now maps negative values, which
+ signal a failure, to 128 and passes everything else through as-is.
+ The only implementations that return a positive value are "apply",
+ "pop" and "branch", which return the value of do_apply_stash():
+ "apply" returns it directly, and "pop" and "branch" drop the stash
+ entry, via do_drop_stash(), which always returns 0, only when the
+ application succeeded. The positive value is always 1, as
+ do_apply_stash() only returns a positive value when the three-way
+ merge was unclean.
+
+ Make the convention explicit by introducing enum stash_apply_result
+ with the values STASH_APPLY_CLEAN, STASH_APPLY_CONFLICT and
+ STASH_APPLY_ERROR, and use it for the in-process autostash helpers,
+ too. They spawn "git stash apply" and can now tell conflicts apart
+ from other failures, e.g. a crash or death by signal of the child,
+ which map to exit statuses above 1. Since we know the stash entry
+ was saved, tell users so in the error message instead of leaving them
+ wondering what happened to their stashed changes.
Signed-off-by: Harald Nordgren [off-list ref]
@@ Documentation/git-stash.adoc: include::includes/cmd-config-section-all.adoc[]
+EXIT STATUS
+-----------
+
-+The `git stash` subcommands exit with status 0 on success and non-zero
-+on failure. The subcommands that apply a stash entry, i.e. `apply`,
-+`pop` and `branch`, exit with status 2 when applying the stash entry
-+resulted in conflicts, in which case the stash entry is left in place.
-+Other failures exit with status 1 (usage errors exit with status 129).
++The `git stash` subcommands exit with status 0 on success. The
++subcommands that apply a stash entry, i.e. `apply`, `pop` and `branch`,
++exit with status 1 when applying the stash entry resulted in conflicts,
++in which case the stash entry is left in place, and with a non-zero
++status other than 1 when they fail for other reasons.
+
SEE ALSO
--------
- ## builtin/checkout.c ##
-@@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
- int flag, writeout_error = 0;
- int do_merge = 1;
- int created_autostash = 0;
-+ enum stash_apply_result autostash_res = STASH_APPLY_CLEAN;
- struct strbuf old_commit_shortname = STRBUF_INIT;
- struct strbuf autostash_msg = STRBUF_INIT;
- const char *stash_label_base = NULL;
-@@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts,
- git_config_push_parameter(cfg.buf);
- strbuf_release(&cfg);
- }
-- apply_autostash_ref(the_repository,
-- "CHECKOUT_AUTOSTASH_HEAD",
-- new_branch_info->name,
-- "local",
-- stash_label_base,
-- autostash_msg.buf);
-+ autostash_res = apply_autostash_ref(the_repository,
-+ "CHECKOUT_AUTOSTASH_HEAD",
-+ new_branch_info->name,
-+ "local",
-+ stash_label_base,
-+ autostash_msg.buf);
- }
- if (ret) {
- branch_info_release(&old_branch_info);
-@@ builtin/checkout.c: 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_res == STASH_APPLY_CONFLICT && !opts->quiet)
-+ fputc('\n', stderr);
- update_refs_for_switch(opts, &old_branch_info, new_branch_info);
-
- if (created_autostash) {
-
## builtin/stash.c ##
@@
#include "object-name.h"
@@ builtin/stash.c: static void unstage_changes_unless_new(struct object_id *orig_t
-static int do_apply_stash(const char *prefix, struct stash_info *info,
- int index, int quiet,
+- const char *label_ours, const char *label_theirs,
+- const char *label_base)
+static enum stash_apply_result do_apply_stash(const char *prefix,
+ struct stash_info *info,
+ int index, int quiet,
- const char *label_ours, const char *label_theirs,
- const char *label_base)
++ const char *label_ours,
++ const char *label_theirs,
++ const char *label_base)
{
+ int clean, ret;
+ int has_index = index;
@@ builtin/stash.c: static int do_apply_stash(const char *prefix, struct stash_info *info,
- clean = merge_ort_nonrecursive(&o, head, merge, merge_base);
/*
-- * If 'clean' >= 0, reverse the value for 'ret' so 'ret' is 0 when the
+ * If 'clean' >= 0, reverse the value for 'ret' so 'ret' is 0 when the
- * merge was clean, and nonzero if the merge was unclean or encountered
- * an error.
-+ * Translate the value of 'clean' so 'ret' is STASH_APPLY_CLEAN
-+ * when the merge was clean, STASH_APPLY_CONFLICT when it was
-+ * unclean, and a negative value if it encountered an error.
++ * merge was clean, and 1 if the merge was unclean or a negative value
++ * if it encountered an error.
*/
-- ret = clean >= 0 ? !clean : clean;
-+ ret = clean >= 0 ? (clean ? STASH_APPLY_CLEAN : STASH_APPLY_CONFLICT)
-+ : clean;
+ ret = clean >= 0 ? !clean : clean;
- if (ret < 0)
- rollback_lock_file(&lock);
-@@ builtin/stash.c: static int do_apply_stash(const char *prefix, struct stash_info *info,
-
- if (has_index) {
- if (reset_tree(&index_tree, 0, 0))
-- ret = -1;
-+ ret = STASH_APPLY_ERROR;
- } else {
- unstage_changes_unless_new(&c_tree);
- }
@@ builtin/stash.c: int cmd_stash(int argc,
strbuf_addf(&stash_index_path, "%s.stash.%" PRIuMAX, index_file,
(uintmax_t)pid);
@@ builtin/stash.c: int cmd_stash(int argc,
+ if (fn) {
+ ret = fn(argc, argv, prefix, repo);
+
++ /*
++ * The subcommand implementations return 0 on success, a
++ * negative value on failure, and STASH_APPLY_CONFLICT
++ * when applying a stash entry resulted in conflicts.
++ * Map failures to 128, the status die() uses, so that
++ * exit status 1 unambiguously indicates conflicts.
++ */
+ if (ret < 0)
-+ return 1;
++ return 128;
+ return ret;
+ } else if (!argc)
return !!push_stash_unassumed(0, NULL, prefix, repo);
@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
strvec_pushf(&child.args, "--label-base=%s", label_base);
strvec_push(&child.args, stash_oid);
ret = run_command(&child);
-+ if (ret && ret != STASH_APPLY_CONFLICT)
++ if (ret > 1)
+ ret = STASH_APPLY_ERROR;
}
@@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte
"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 if (attempt_apply)
-+ ret = error(_("could not apply autostash"));
++ ret = error(_("could not apply autostash; "
++ "your changes are safe in the stash"));
else
fprintf(stderr,
_("Autostash exists; creating a new stash entry.\n"
@@ stash.h (new)
+ * The stash could not be applied because it resulted in
+ * conflicts. The stash entry is left in place. The "git stash
+ * apply", "pop" and "branch" subcommands exit with this status
-+ * in this case.
++ * in this case, mirroring the convention of "git merge-tree" and
++ * the merge strategies.
+ */
-+ STASH_APPLY_CONFLICT = 2,
++ STASH_APPLY_CONFLICT = 1,
+
+ /* Something went wrong. */
+ STASH_APPLY_ERROR = -1,
@@ stash.h (new)
+#endif /* STASH_H */
## t/t3903-stash.sh ##
-@@ t/t3903-stash.sh: test_expect_success 'apply with custom conflict labels' '
+@@ t/t3903-stash.sh: test_expect_success 'stash.index=false overridden by --index' '
+ test_cmp expect file
+ '
+
+-test_expect_success 'apply with custom conflict labels' '
++test_expect_success 'apply exits 1 on conflicts' '
+ git reset --hard initial &&
+ test_commit label-base conflict-file base-content &&
echo stashed >conflict-file &&
git stash push -m "stashed" &&
test_commit label-upstream conflict-file upstream-content &&
- test_must_fail git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
-+ test_expect_code 2 git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
++ test_expect_code 1 git -c merge.conflictStyle=diff3 stash apply --label-ours=UP --label-theirs=STASH &&
test_grep "^<<<<<<< UP" conflict-file &&
test_grep "^||||||| Stash base" conflict-file &&
test_grep "^>>>>>>> STASH" conflict-file
@@ t/t3903-stash.sh: test_expect_success 'apply with empty conflict labels' '
git stash push -m "stashed" &&
test_commit empty-label-upstream conflict-file upstream-content &&
- test_must_fail git stash apply --label-ours= --label-theirs= &&
-+ test_expect_code 2 git stash apply --label-ours= --label-theirs= &&
++ test_expect_code 1 git stash apply --label-ours= --label-theirs= &&
test_grep "^<<<<<<<$" conflict-file &&
test_grep "^>>>>>>>$" conflict-file
'
-+test_expect_success 'apply exits 2 on conflicts and keeps the stash entry' '
++test_expect_success 'pop exits 1 on conflicts and keeps the stash entry' '
+ git reset --hard initial &&
-+ test_commit exit-code-base conflict-file base-content &&
-+ echo stashed >conflict-file &&
-+ git stash push -m stashed &&
-+ test_commit exit-code-upstream conflict-file upstream-content &&
-+ test_expect_code 2 git stash apply &&
++ echo stashed >file &&
++ git stash push -m pop-stashed &&
++ test_commit pop-upstream file upstream-content &&
++ test_expect_code 1 git stash pop &&
+ git stash list >list &&
-+ test_grep stashed list
++ test_grep pop-stashed list
+'
+
-+test_expect_success 'pop exits 2 on conflicts and keeps the stash entry' '
++test_expect_success 'stash branch exits with a non-1 status on errors' '
+ git reset --hard initial &&
-+ test_commit pop-exit-code-base pop-file base-content &&
-+ echo stashed >pop-file &&
-+ git stash push -m pop-stashed &&
-+ test_commit pop-exit-code-upstream pop-file upstream-content &&
-+ test_expect_code 2 git stash pop &&
++ echo stashed >file &&
++ git stash push -m branch-stashed &&
++ test_expect_code 128 git stash branch conflicting-branch refs/heads/does-not-exist &&
+ git stash list >list &&
-+ test_grep pop-stashed list
++ test_grep branch-stashed list
+'
+
test_expect_success 'stash show --include-untracked includes untracked files' '
git reset --hard &&
-
- ## t/t7201-co.sh ##
-@@ t/t7201-co.sh: test_expect_success 'checkout -m creates a recoverable stash on conflict' '
- test_must_fail git checkout side 2>stderr &&
- test_grep "Your local changes" stderr &&
- git checkout -m side >actual 2>&1 &&
-- test_grep "resulted in conflicts" actual &&
-- test_grep "git stash drop" actual &&
-- test_grep "git stash pop" actual &&
-- test_grep "The following paths have local changes" actual &&
-+ cat >expect <<-EOF &&
-+ Your local changes are stashed, however applying them
-+ resulted in conflicts. You can either resolve the conflicts
-+ and then discard the stash with "git stash drop", or, if you
-+ do not want to resolve them now, run "git reset --hard" and
-+ apply the local changes later by running "git stash pop".
-+
-+ Switched to branch ${SQ}side${SQ}
-+ The following paths have local changes:
-+ M one
-+ EOF
-+ test_cmp expect 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 &&
-: ---------- > 2: 935fa0a9ae checkout: separate autostash conflict advice from branch-switch message