[v2,2/2] stash: handle staged changes in skip-worktree files correctly

Commit Message

Linus Arver via GitGitGadget Oct. 28, 2019, 11:20 a.m. UTC

From: Johannes Schindelin <[e-mail]>

When calling `git stash` while changes were staged for files that are
marked with the `skip-worktree` bit (e.g. files that are excluded in a
sparse checkout), the files are recorded as _deleted_ instead.

The reason is that `git stash` tries to construct the tree reflecting
the worktree essentially by copying the index to a temporary one and
then updating the files from the worktree. Crucially, it calls `git
diff-index` to update also those files that are in the HEAD but have
been unstaged in the index.

However, when the temporary index is updated via `git update-index --add
--remove`, skip-worktree entries mark the files as deleted by mistake.

Let's use the newly-introduced `--ignore-skip-worktree-entries` option
of `git update-index` to prevent exactly this from happening.

Note that the regression test case deliberately avoids replicating the
scenario described above and instead tries to recreate just the symptom.

Reported by Dan Thompson.

Signed-off-by: Johannes Schindelin <[e-mail]>
---
 builtin/stash.c     |  5 +++--
 git-legacy-stash.sh |  3 ++-
 t/t3903-stash.sh    | 11 +++++++++++
 3 files changed, 16 insertions(+), 3 deletions(-)

Comments

Junio C Hamano Oct. 30, 2019, 1:16 a.m. UTC | #1

"Johannes Schindelin via GitGitGadget" <[e-mail]>
writes:

> From: Johannes Schindelin <[e-mail]>
>
> When calling `git stash` while changes were staged for files that are
> marked with the `skip-worktree` bit (e.g. files that are excluded in a
> sparse checkout), the files are recorded as _deleted_ instead.

Good.  Much easier to see what is going on than the verb "lose" used
in the cover letter of v1 that puzzled me.

> However, when the temporary index is updated via `git update-index --add
> --remove`, skip-worktree entries mark the files as deleted by mistake.
>
> Let's use the newly-introduced `--ignore-skip-worktree-entries` option
> of `git update-index` to prevent exactly this from happening.

Good.

> Note that the regression test case deliberately avoids replicating the
> scenario described above and instead tries to recreate just the symptom.

That's good.  Testing the end-user visible effect is just as
important as the narrowly pointed root-cause test like the one in
the previous patch.

Thanks.

Patch

diff --git a/builtin/stash.c b/builtin/stash.c
index ab30d1e920..e3962bf73e 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -1082,8 +1082,9 @@  static int stash_working_tree(struct stash_info *info, const struct pathspec *ps
 	}
 
 	cp_upd_index.git_cmd = 1;
-	argv_array_pushl(&cp_upd_index.args, "update-index", "-z", "--add",
-			 "--remove", "--stdin", NULL);
+	argv_array_pushl(&cp_upd_index.args, "update-index",
+			 "--ignore-skip-worktree-entries",
+			 "-z", "--add", "--remove", "--stdin", NULL);
 	argv_array_pushf(&cp_upd_index.env_array, "GIT_INDEX_FILE=%s",
 			 stash_index_path.buf);
 
diff --git a/git-legacy-stash.sh b/git-legacy-stash.sh
index f60e9b3e87..5398a5161d 100755
--- a/git-legacy-stash.sh
+++ b/git-legacy-stash.sh
@@ -193,7 +193,8 @@  create_stash () {
 			GIT_INDEX_FILE="$TMPindex" &&
 			export GIT_INDEX_FILE &&
 			git diff-index --name-only -z HEAD -- "$@" >"$TMP-stagenames" &&
-			git update-index -z --add --remove --stdin <"$TMP-stagenames" &&
+			git update-index --ignore-skip-worktree-entries \
+				-z --add --remove --stdin <"$TMP-stagenames" &&
 			git write-tree &&
 			rm -f "$TMPindex"
 		) ) ||
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 392954d6dd..57258d5668 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1257,4 +1257,15 @@  test_expect_success 'stash apply should succeed with unmodified file' '
 	git stash apply
 '
 
+test_expect_success 'stash handles skip-worktree entries nicely' '
+	test_commit A &&
+	echo changed >A.t &&
+	git add A.t &&
+	git update-index --skip-worktree A.t &&
+	rm A.t &&
+	git stash &&
+
+	git rev-parse --verify refs/stash:A.t
+'
+
 test_done