[PATCH v2 4/4] submodule: cache superproject gitdir during 'update'

From: Emily Shaffer <emilyshaffer@google.com>
To: git@vger.kernel.org
Cc: Emily Shaffer <emilyshaffer@google.com>
Subject: [PATCH v2 4/4] submodule: cache superproject gitdir during 'update'
Date: Tue, 15 Jun 2021 17:45:08 -0700	[thread overview]
Message-ID: <20210616004508.87186-5-emilyshaffer@google.com> (raw)
In-Reply-To: <20210616004508.87186-1-emilyshaffer@google.com>

A cached path to the superproject's gitdir might be added during 'git
submodule add', but in some cases - like submodules which were created
before 'git submodule add' learned to cache that info - it might be
useful to update the cache. Let's do it during 'git submodule update',
when we already have a handle to the superproject while calling
operations on the submodules.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
---
 git-submodule.sh            | 10 ++++++++++
 t/t7406-submodule-update.sh | 10 ++++++++++
 2 files changed, 20 insertions(+)

diff --git a/git-submodule.sh b/git-submodule.sh
index 4678378424..f98dcc16ae 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -648,6 +648,16 @@ cmd_update()
 			fi
 		fi
 
+		# Cache a pointer to the superproject's gitdir. This may have
+		# changed, so rewrite it unconditionally. Writes it to worktree
+		# if applicable, otherwise to local.
+		relative_gitdir="$(git rev-parse --path-format=relative \
+						 --prefix "${sm_path}" \
+						 --git-dir)"
+
+		git -C "$sm_path" config --worktree \
+			submodule.superprojectgitdir "$relative_gitdir"
+
 		if test -n "$recursive"
 		then
 			(
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index f4f61fe554..c39821ba8e 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -1061,4 +1061,14 @@ test_expect_success 'submodule update --quiet passes quietness to fetch with a s
 	)
 '
 
+test_expect_success 'submodule update adds superproject gitdir to older repos' '
+	(cd super &&
+	 git -C submodule config --unset submodule.superprojectGitdir &&
+	 git submodule update &&
+	 echo "../.git" >expect &&
+	 git -C submodule config submodule.superprojectGitdir >actual &&
+	 test_cmp expect actual
+	)
+'
+
 test_done
-- 
2.32.0.272.g935e593368-goog

