From: Phillip Wood Date: Tue, 28 Apr 2026 09:35:34 GMT Subject: Re: [PATCH v15 0/5] checkout: 'autostash' for branch switching Message-ID: In-Reply-To: Hi Harald On 24/04/2026 22:10, Harald Nordgren via GitGitGadget wrote: > * When the initial merge fails, the caller now knows for sure it was a > conflict (not some unrelated error) before kicking off the autostash. > > * If the second attempt also fails, the user now actually sees why. > Previously errors like "would be overwritten by checkout" were being > swallowed. > > * The stash is reapplied right after the second attempt, so it won't get > left behind if something else goes wrong later in the checkout. > > * A couple of clean-up steps only run when we actually stashed, so regular > checkouts aren't paying for work they don't need. > > * Added a small header "The following paths have local changes:" before the > list of changed files, so it doesn't look like part of the conflict > advice above it. > > * Reworded the conflict advice into a single paragraph. Feels less shouty > and doesn't say "local changes" three times. > > * Trimmed and consolidated tests in t7201. A bunch of the old ones couldn't > actually fail, or were really testing other things; the conflict-path > tests are now a single test that checks the stash entry directly. Thanks for the summary, that all looks good. I've left some comments on Patches 1 and 3 but they can be future work and don't need to hold this series up. There are a few small issues that need addressing on Patch 5 but hopefully the next iteration will be the last. Thanks Phillip > Harald Nordgren (5): > stash: add --label-ours, --label-theirs, --label-base for apply > sequencer: allow create_autostash to run silently > sequencer: teach autostash apply to take optional conflict marker > labels > checkout: rollback lock on early returns in merge_working_tree > checkout -m: autostash when switching branches > > Documentation/git-checkout.adoc | 58 +++++------ > Documentation/git-stash.adoc | 11 ++- > Documentation/git-switch.adoc | 33 +++---- > builtin/checkout.c | 165 +++++++++++++++----------------- > builtin/commit.c | 3 +- > builtin/merge.c | 15 ++- > builtin/stash.c | 28 ++++-- > sequencer.c | 69 +++++++++---- > sequencer.h | 7 +- > t/t3420-rebase-autostash.sh | 16 ++-- > t/t3903-stash.sh | 24 +++++ > t/t7201-co.sh | 61 +++++++++++- > t/t7600-merge.sh | 3 +- > xdiff-interface.c | 12 +++ > xdiff-interface.h | 1 + > xdiff/xmerge.c | 6 +- > 16 files changed, 335 insertions(+), 177 deletions(-) > > > base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0 > Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2234%2FHaraldNordgren%2Fcheckout_autostash-v15 > Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2234/HaraldNordgren/checkout_autostash-v15 > Pull-Request: https://github.com/git/git/pull/2234 > > Range-diff vs v14: > > 1: e18c25599a = 1: aba8e6a9dc stash: add --label-ours, --label-theirs, --label-base for apply > 2: ce29b10264 = 2: 89e0bfa803 sequencer: allow create_autostash to run silently > 3: 73051d1762 = 3: a428ce7328 sequencer: teach autostash apply to take optional conflict marker labels > 4: 191058d8e3 = 4: f358424085 checkout: rollback lock on early returns in merge_working_tree > 5: 86f33df1eb ! 5: 96b14db827 checkout -m: autostash when switching branches > @@ builtin/checkout.c > #include "setup.h" > #include "submodule.h" > #include "symlinks.h" > +@@ builtin/checkout.c: struct checkout_opts { > + .auto_advance = 1, \ > + } > + > ++#define MERGE_WORKING_TREE_UNPACK_FAILED (-2) > ++ > + struct branch_info { > + char *name; /* The short name used */ > + char *path; /* The full name of a real branch */ > +@@ builtin/checkout.c: static void setup_branch_path(struct branch_info *branch) > + > + static void init_topts(struct unpack_trees_options *topts, int merge, > + int show_progress, int overwrite_ignore, > +- struct commit *old_commit) > ++ struct commit *old_commit, bool show_unpack_errors) > + { > + memset(topts, 0, sizeof(*topts)); > + topts->head_idx = -1; > +@@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, int merge, > + topts->initial_checkout = is_index_unborn(the_repository->index); > + topts->update = 1; > + topts->merge = 1; > +- topts->quiet = merge && old_commit; > ++ topts->quiet = merge && old_commit && !show_unpack_errors; > + topts->verbose_update = show_progress; > + topts->fn = twoway_merge; > + topts->preserve_ignored = !overwrite_ignore; > +@@ builtin/checkout.c: static void init_topts(struct unpack_trees_options *topts, int merge, > + static int merge_working_tree(const struct checkout_opts *opts, > + struct branch_info *old_branch_info, > + struct branch_info *new_branch_info, > +- int *writeout_error) > ++ int *writeout_error, > ++ bool show_unpack_errors) > + { > + int ret; > + struct lock_file lock_file = LOCK_INIT; > +@@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts, > + > + /* 2-way merge to the new branch */ > + init_topts(&topts, opts->merge, opts->show_progress, > +- opts->overwrite_ignore, old_branch_info->commit); > ++ opts->overwrite_ignore, old_branch_info->commit, > ++ show_unpack_errors); > + init_checkout_metadata(&topts.meta, new_branch_info->refname, > + new_branch_info->commit ? > + &new_branch_info->commit->object.oid : > @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *opts, > ret = unpack_trees(2, trees, &topts); > clear_unpack_trees_porcelain(&topts); > @@ builtin/checkout.c: static int merge_working_tree(const struct checkout_opts *op > - return ret; > - } > + rollback_lock_file(&lock_file); > -+ return ret; > ++ return MERGE_WORKING_TREE_UNPACK_FAILED; > } > } > > @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts, > do_merge = 0; > } > > -+ if (old_branch_info.name) > ++ if (old_branch_info.name) { > + stash_label_base = old_branch_info.name; > -+ else if (old_branch_info.commit) { > ++ } else if (old_branch_info.commit) { > + strbuf_add_unique_abbrev(&old_commit_shortname, > + &old_branch_info.commit->object.oid, > + DEFAULT_ABBREV); > @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts, > + } > + > if (do_merge) { > - ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error); > -+ if (ret == -1 && opts->merge) { > +- ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error); > ++ ret = merge_working_tree(opts, &old_branch_info, new_branch_info, > ++ &writeout_error, false); > ++ if (ret == MERGE_WORKING_TREE_UNPACK_FAILED && opts->merge) { > + strbuf_addf(&autostash_msg, > + "autostash while switching to '%s'", > + new_branch_info->name); > @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts, > + "CHECKOUT_AUTOSTASH_HEAD", > + autostash_msg.buf, true); > + created_autostash = 1; > -+ ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error); > ++ ret = merge_working_tree(opts, &old_branch_info, new_branch_info, > ++ &writeout_error, true); > ++ } > ++ if (created_autostash) { > ++ if (opts->conflict_style >= 0) { > ++ struct strbuf cfg = STRBUF_INIT; > ++ strbuf_addf(&cfg, "merge.conflictStyle=%s", > ++ conflict_style_name(opts->conflict_style)); > ++ git_config_push_parameter(cfg.buf); > ++ strbuf_release(&cfg); > ++ } > ++ apply_autostash_ref(the_repository, > ++ "CHECKOUT_AUTOSTASH_HEAD", > ++ new_branch_info->name, > ++ "local", > ++ stash_label_base, > ++ autostash_msg.buf); > + } > if (ret) { > -+ if (created_autostash) > -+ apply_autostash_ref(the_repository, > -+ "CHECKOUT_AUTOSTASH_HEAD", > -+ new_branch_info->name, > -+ "local", > -+ stash_label_base, > -+ autostash_msg.buf); > branch_info_release(&old_branch_info); > - return ret; > + strbuf_release(&old_commit_shortname); > @@ builtin/checkout.c: static int switch_branches(const struct checkout_opts *opts, > > update_refs_for_switch(opts, &old_branch_info, new_branch_info); > > -+ if (opts->conflict_style >= 0) { > -+ struct strbuf cfg = STRBUF_INIT; > -+ strbuf_addf(&cfg, "merge.conflictStyle=%s", > -+ conflict_style_name(opts->conflict_style)); > -+ git_config_push_parameter(cfg.buf); > -+ strbuf_release(&cfg); > ++ if (created_autostash) { > ++ discard_index(the_repository->index); > ++ if (repo_read_index(the_repository) < 0) > ++ die(_("index file corrupt")); > ++ > ++ if (!opts->quiet && new_branch_info->commit) { > ++ printf(_("The following paths have local changes:\n")); > ++ show_local_changes(&new_branch_info->commit->object, > ++ &opts->diff_options); > ++ } > + } > -+ apply_autostash_ref(the_repository, "CHECKOUT_AUTOSTASH_HEAD", > -+ new_branch_info->name, "local", > -+ stash_label_base, > -+ autostash_msg.buf); > -+ > -+ discard_index(the_repository->index); > -+ if (repo_read_index(the_repository) < 0) > -+ die(_("index file corrupt")); > -+ > -+ if (created_autostash && !opts->quiet && new_branch_info->commit) > -+ show_local_changes(&new_branch_info->commit->object, > -+ &opts->diff_options); > + > ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1); > branch_info_release(&old_branch_info); > @@ sequencer.c: static int apply_save_autostash_oid(const char *stash_oid, int atte > ret = error(_("cannot store %s"), stash_oid); > + else if (attempt_apply) > + fprintf(stderr, > -+ _("Your local changes are stashed, however, applying it to carry\n" > -+ "forward your local changes resulted in conflicts:\n" > -+ "\n" > -+ " - You can try resolving them now. If you resolved them\n" > -+ " successfully, discard the stash entry with \"git stash drop\".\n" > -+ "\n" > -+ " - Alternatively you can \"git reset --hard\" if you do not want\n" > -+ " to deal with them right now, and later \"git stash pop\" to\n" > -+ " recover your local changes.\n")); > ++ _("Your local changes are stashed, however applying them\n" > ++ "resulted in conflicts. You can either resolve the conflicts\n" > ++ "and then discard the stash with \"git stash drop\", or, if you\n" > ++ "do not want to resolve them now, run \"git reset --hard\" and\n" > ++ "apply the local changes later by running \"git stash pop\".\n")); > else > fprintf(stderr, > - _("%s\n" > @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () { > - Applying autostash resulted in conflicts. > - Your changes are safe in the stash. > - You can run "git stash pop" or "git stash drop" at any time. > -+ Your local changes are stashed, however, applying it to carry > -+ forward your local changes resulted in conflicts: > -+ > -+ - You can try resolving them now. If you resolved them > -+ successfully, discard the stash entry with "git stash drop". > -+ > -+ - Alternatively you can "git reset --hard" if you do not want > -+ to deal with them right now, and later "git stash pop" to > -+ recover your local changes. > ++ Your local changes are stashed, however applying them > ++ resulted in conflicts. You can either resolve the conflicts > ++ and then discard the stash with "git stash drop", or, if you > ++ do not want to resolve them now, run "git reset --hard" and > ++ apply the local changes later by running "git stash pop". > EOF > } > > @@ t/t3420-rebase-autostash.sh: create_expected_failure_apply () { > - Applying autostash resulted in conflicts. > - Your changes are safe in the stash. > - You can run "git stash pop" or "git stash drop" at any time. > -+ Your local changes are stashed, however, applying it to carry > -+ forward your local changes resulted in conflicts: > -+ > -+ - You can try resolving them now. If you resolved them > -+ successfully, discard the stash entry with "git stash drop". > -+ > -+ - Alternatively you can "git reset --hard" if you do not want > -+ to deal with them right now, and later "git stash pop" to > -+ recover your local changes. > ++ Your local changes are stashed, however applying them > ++ resulted in conflicts. You can either resolve the conflicts > ++ and then discard the stash with "git stash drop", or, if you > ++ do not want to resolve them now, run "git reset --hard" and > ++ apply the local changes later by running "git stash pop". > Successfully rebased and updated refs/heads/rebased-feature-branch. > EOF > } > > ## t/t7201-co.sh ## > +@@ t/t7201-co.sh: test_expect_success 'checkout -m with dirty tree' ' > + > + test "$(git symbolic-ref HEAD)" = "refs/heads/side" && > + > +- printf "M\t%s\n" one >expect.messages && > ++ printf "The following paths have local changes:\nM\t%s\n" one >expect.messages && > + test_cmp expect.messages messages && > + > + fill "M one" "A three" "D two" >expect.main && > @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 ' ' > test_cmp expect two > ' > > -+test_expect_success 'checkout --merge --conflict=zdiff3 ' ' > -+ git checkout -f main && > -+ git reset --hard && > -+ git clean -f && > -+ > -+ fill a b X d e >two && > -+ git checkout --merge --conflict=zdiff3 simple && > -+ > -+ cat <<-EOF >expect && > -+ a > -+ <<<<<<< simple > -+ c > -+ ||||||| main > -+ b > -+ c > -+ d > -+ ======= > -+ b > -+ X > -+ d > -+ >>>>>>> local > -+ e > -+ EOF > -+ test_cmp expect two > -+' > -+ > -+test_expect_success 'checkout -m respects merge.conflictStyle config' ' > -+ git checkout -f main && > -+ git reset --hard && > -+ git clean -f && > -+ > -+ test_config merge.conflictStyle diff3 && > -+ fill b d >two && > -+ git checkout -m simple && > -+ > -+ cat <<-EOF >expect && > -+ <<<<<<< simple > -+ a > -+ c > -+ e > -+ ||||||| main > -+ a > -+ b > -+ c > -+ d > -+ e > -+ ======= > -+ b > -+ d > -+ >>>>>>> local > -+ EOF > -+ test_cmp expect two > -+' > -+ > -+test_expect_success 'checkout -m skips stash when no conflict' ' > -+ git checkout -f main && > -+ git clean -f && > -+ > -+ fill 0 x y z >same && > -+ git stash list >stash-before && > -+ git checkout -m side >actual 2>&1 && > -+ test_grep ! "Created autostash" actual && > -+ git stash list >stash-after && > -+ test_cmp stash-before stash-after && > -+ fill 0 x y z >expect && > -+ test_cmp expect same > -+' > -+ > -+test_expect_success 'checkout -m skips stash with non-conflicting dirty index' ' > -+ git checkout -f main && > -+ git clean -f && > -+ > -+ fill 0 x y z >same && > -+ git add same && > -+ git checkout -m side >actual 2>&1 && > -+ test_grep ! "Created autostash" actual && > -+ fill 0 x y z >expect && > -+ test_cmp expect same > -+' > -+ > -+test_expect_success 'checkout -m stashes and applies on conflicting changes' ' > -+ git checkout -f main && > -+ git clean -f && > -+ > -+ fill 1 2 3 4 5 6 7 >one && > -+ git checkout -m side >actual 2>&1 && > -+ test_grep ! "Created autostash" actual && > -+ test_grep "Applied autostash" actual && > -+ fill 1 2 3 4 5 6 7 >expect && > -+ test_cmp expect one > -+' > -+ > +test_expect_success 'checkout -m with mixed staged and unstaged changes' ' > + git checkout -f main && > + git clean -f && > @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 ' > + git add same && > + fill 1 2 3 4 5 6 7 >one && > + git checkout -m side >actual 2>&1 && > -+ test_grep ! "Created autostash" actual && > + test_grep "Applied autostash" actual && > + fill 0 x y z >expect && > + test_cmp expect same && > @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 ' > + test_cmp expect one > +' > + > -+test_expect_success 'checkout -m stashes on truly conflicting changes' ' > ++test_expect_success 'checkout -m creates a recoverable stash on conflict' ' > + git checkout -f main && > + git clean -f && > + > @@ t/t7201-co.sh: test_expect_success 'checkout --merge --conflict=diff3 ' > + test_must_fail git checkout side 2>stderr && > + test_grep "Your local changes" stderr && > + git checkout -m side >actual 2>&1 && > -+ test_grep ! "Created autostash" actual && > + test_grep "resulted in conflicts" actual && > + test_grep "git stash drop" actual && > ++ test_grep "git stash pop" actual && > ++ test_grep "The following paths have local changes" actual && > ++ git show --format=%B --diff-merges=1 refs/stash >actual && > ++ sed /^index/d actual >actual.trimmed && > ++ cat >expect <<-EOF && > ++ On main: autostash while switching to ${SQ}side${SQ} > ++ > ++ diff --git a/one b/one > ++ --- a/one > ++ +++ b/one > ++ @@ -3,6 +3,3 @@ > ++ 3 > ++ 4 > ++ 5 > ++ -6 > ++ -7 > ++ -8 > ++ EOF > ++ test_cmp expect actual.trimmed && > + git stash drop && > + git reset --hard > +' > + > -+test_expect_success 'checkout -m produces usable stash on conflict' ' > -+ git checkout -f main && > -+ git clean -f && > -+ > ++test_expect_success 'checkout -m which would overwrite untracked file' ' > ++ git checkout -f --detach main && > ++ test_commit another-file && > ++ git checkout HEAD^ && > ++ >another-file.t && > + fill 1 2 3 4 5 >one && > -+ git checkout -m side >actual 2>&1 && > -+ test_grep "recover your local changes" actual && > -+ git checkout -f main && > -+ git stash pop && > -+ fill 1 2 3 4 5 >expect && > -+ test_cmp expect one > -+' > -+ > -+test_expect_success 'checkout -m autostash message includes target branch' ' > -+ git checkout -f main && > -+ git clean -f && > -+ > -+ fill 1 2 3 4 5 >one && > -+ git checkout -m side >actual 2>&1 && > -+ git stash list >stash-list && > -+ test_grep "autostash while switching to .side." stash-list && > -+ git stash drop && > -+ git checkout -f main && > -+ git reset --hard > -+' > -+ > -+test_expect_success 'checkout -m stashes on staged conflicting changes' ' > -+ git checkout -f main && > -+ git clean -f && > -+ > -+ fill 1 2 3 4 5 >one && > -+ git add one && > -+ git checkout -m side >actual 2>&1 && > -+ test_grep ! "Created autostash" actual && > -+ test_grep "resulted in conflicts" actual && > -+ test_grep "git stash drop" actual && > -+ git stash drop && > -+ git reset --hard > -+' > -+ > -+test_expect_success 'checkout -m applies stash cleanly with non-overlapping changes in same file' ' > -+ git checkout -f main && > -+ git reset --hard && > -+ git clean -f && > -+ > -+ git checkout -b nonoverlap_base && > -+ fill a b c d >file && > -+ git add file && > -+ git commit -m "add file" && > -+ > -+ git checkout -b nonoverlap_child && > -+ fill a b c INSERTED d >file && > -+ git commit -a -m "insert line near end of file" && > -+ > -+ fill DIRTY a b c INSERTED d >file && > -+ > -+ git stash list >stash-before && > -+ git checkout -m nonoverlap_base 2>stderr && > -+ test_grep "Applied autostash" stderr && > -+ test_grep ! "resulted in conflicts" stderr && > -+ > -+ git stash list >stash-after && > -+ test_cmp stash-before stash-after && > -+ > -+ fill DIRTY a b c d >expect && > -+ test_cmp expect file && > -+ > -+ git checkout -f main && > -+ git branch -D nonoverlap_base && > -+ git branch -D nonoverlap_child > -+' > -+ > -+test_expect_success 'checkout -m -b skips stash with dirty tree' ' > -+ git checkout -f main && > -+ git clean -f && > -+ > -+ fill 0 x y z >same && > -+ git checkout -m -b newbranch >actual 2>&1 && > -+ test_grep ! "Created autostash" actual && > -+ fill 0 x y z >expect && > -+ test_cmp expect same && > -+ git checkout main && > -+ git branch -D newbranch > ++ test_must_fail git checkout -m @{-1} 2>err && > ++ test_grep "would be overwritten by checkout" err && > ++ test_grep "another-file.t" err > +' > + > test_expect_success 'switch to another branch while carrying a deletion' ' > @@ t/t7600-merge.sh: test_expect_success 'merge with conflicted --autostash changes > test_when_finished "test_might_fail git stash drop" && > git merge --autostash c3 2>err && > - test_grep "Applying autostash resulted in conflicts." err && > -+ test_grep "your local changes resulted in conflicts" err && > ++ test_grep "applying them" err && > ++ test_grep "resulted in conflicts" err && > git show HEAD:file >merge-result && > test_cmp result.1-9 merge-result && > git stash show -p >actual && >