[PATCH v3 3/4] submodule: record superproject gitdir during absorbgitdirs

[Emily Shaffer <emilyshaffer@google.com>]

Already during 'git submodule add' we record a pointer to the
superproject's gitdir. However, this doesn't help brand-new
submodules created with 'git init' and later absorbed with 'git
submodule absorbgitdir'. Let's start adding that pointer during 'git
submodule absorbgitdir' too.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
---
 submodule.c                        | 10 ++++++++++
 t/t7412-submodule-absorbgitdirs.sh |  9 ++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/submodule.c b/submodule.c
index 0b1d9c1dde..4b314bf09c 100644
--- a/submodule.c
+++ b/submodule.c
@@ -2065,6 +2065,7 @@ static void relocate_single_git_dir_into_superproject(const char *path)
 	char *old_git_dir = NULL, *real_old_git_dir = NULL, *real_new_git_dir = NULL;
 	char *new_git_dir;
 	const struct submodule *sub;
+	struct strbuf config_path = STRBUF_INIT, sb = STRBUF_INIT;
 
 	if (submodule_uses_worktrees(path))
 		die(_("relocate_gitdir for submodule '%s' with "
@@ -2096,6 +2097,15 @@ static void relocate_single_git_dir_into_superproject(const char *path)
 
 	relocate_gitdir(path, real_old_git_dir, real_new_git_dir);
 
+	/* cache pointer to superproject's gitdir */
+	/* NEEDSWORK: this may differ if experimental.worktreeConfig is enabled */
+	strbuf_addf(&config_path, "%s/config", real_new_git_dir);
+	git_config_set_in_file(config_path.buf, "submodule.superprojectGitdir",
+			       relative_path(get_super_prefix_or_empty(),
+					     path, &sb));
+
+	strbuf_release(&config_path);
+	strbuf_release(&sb);
 	free(old_git_dir);
 	free(real_old_git_dir);
 	free(real_new_git_dir);
diff --git a/t/t7412-submodule-absorbgitdirs.sh b/t/t7412-submodule-absorbgitdirs.sh
index 1cfa150768..e2d78e01df 100755
--- a/t/t7412-submodule-absorbgitdirs.sh
+++ b/t/t7412-submodule-absorbgitdirs.sh
@@ -30,7 +30,14 @@ test_expect_success 'absorb the git dir' '
 	git status >actual.1 &&
 	git -C sub1 rev-parse HEAD >actual.2 &&
 	test_cmp expect.1 actual.1 &&
-	test_cmp expect.2 actual.2
+	test_cmp expect.2 actual.2 &&
+
+	# make sure the submodule cached the superproject gitdir correctly
+	test-tool path-utils real_path . >expect &&
+	test-tool path-utils real_path \
+		"$(git -C sub1 config submodule.superprojectGitDir)" >actual &&
+
+	test_cmp expect actual
 '
 
 test_expect_success 'absorbing does not fail for deinitialized submodules' '
-- 
2.33.0.rc2.250.ged5fa647cd-goog