[PATCH v4] stash: avoid recursive hard reset on submodules

[Jakob Jarmar <jakob.j@xxxxxxxxx>]

git stash push does not recursively stash submodules, but if
submodule.recurse is set, it may recursively reset --hard them. Having
only the destructive action recurse is likely to be surprising
behaviour, and unlikely to be desirable, so the easiest fix should be to
ensure that the call to git reset --hard never recurses into submodules.

This matches the behavior of check_changes_tracked_files, which ignores
submodules.

Signed-off-by: Jakob Jarmar <jakob@xxxxxxxxx>
---

Notes:
    1. Added space between function name and parentheses
    2. Moved test_when_finished cleanup to top of setup_basic

 builtin/stash.c            |  2 +-
 git-legacy-stash.sh        |  2 +-
 t/t3906-stash-submodule.sh | 42 +++++++++++++++++++++++++++++++++++++-
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/builtin/stash.c b/builtin/stash.c
index b5a301f24d..c986c258f2 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -1383,7 +1383,7 @@ static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int q
 			struct child_process cp = CHILD_PROCESS_INIT;
 			cp.git_cmd = 1;
 			argv_array_pushl(&cp.args, "reset", "--hard", "-q",
-					 NULL);
+					 "--no-recurse-submodules", NULL);
 			if (run_command(&cp)) {
 				ret = -1;
 				goto done;
diff --git a/git-legacy-stash.sh b/git-legacy-stash.sh
index f60e9b3e87..07ad4a5459 100755
--- a/git-legacy-stash.sh
+++ b/git-legacy-stash.sh
@@ -370,7 +370,7 @@ push_stash () {
 			git diff-index -p --cached --binary HEAD -- "$@" |
 			git apply --index -R
 		else
-			git reset --hard -q
+			git reset --hard -q --no-recurse-submodules
 		fi
 
 		if test "$keep_index" = "t" && test -n "$i_tree"
diff --git a/t/t3906-stash-submodule.sh b/t/t3906-stash-submodule.sh
index d7219d6f8f..b93d1d74da 100755
--- a/t/t3906-stash-submodule.sh
+++ b/t/t3906-stash-submodule.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-test_description='stash apply can handle submodules'
+test_description='stash can handle submodules'
 
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-submodule-update.sh
@@ -21,4 +21,44 @@ KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT=1
 KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
 test_submodule_switch "git_stash"
 
+setup_basic () {
+	test_when_finished "rm -rf main sub" &&
+	git init sub &&
+	(
+		cd sub &&
+		test_commit sub_file
+	) &&
+	git init main &&
+	(
+		cd main &&
+		git submodule add ../sub &&
+		test_commit main_file
+	)
+}
+
+test_expect_success 'stash push with submodule.recurse=true preserves dirty submodule worktree' '
+	setup_basic &&
+	(
+		cd main &&
+		git config submodule.recurse true &&
+		echo "x" >main_file.t &&
+		echo "y" >sub/sub_file.t &&
+		git stash push &&
+		test_must_fail git -C sub diff --quiet
+	)
+'
+
+test_expect_success 'stash push and pop with submodule.recurse=true preserves dirty submodule worktree' '
+	setup_basic &&
+	(
+		cd main &&
+		git config submodule.recurse true &&
+		echo "x" >main_file.t &&
+		echo "y" >sub/sub_file.t &&
+		git stash push &&
+		git stash pop &&
+		test_must_fail git -C sub diff --quiet
+	)
+'
+
 test_done
-- 
2.23.0