[PATCH v5 5/9] builtin/clone: move setup of alternates for shared local clones

From: Patrick Steinhardt <ps@pks.im>
Date: Sep 10, 2026, 15:09 UTC
Message-ID: <20260910-pks-odb-write-alternates-at-creation-time-v5-5-8d10c4238edc@pks.im>
In-Reply-To: <20260910-pks-odb-write-alternates-at-creation-time-v5-0-8d10c4238edc@pks.im>

When cloning a local repository with "--shared" we add that repository to the new repository's alternates. This is done in `clone_local()`, which is responsible for performing local clones.

Move the logic into `collect_alternates()` to unify our setup of alternates. Furthermore, this will allow us to set up alternates right at creation time of the object database.

Note that the logic for cloning a local repository with "--no-shared" is not yet part of `collect_alternates()`. This will be handled in the next commit, but means that at this step, we may compute `commondir` without it being used. It will become used in the next step though.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 builtin/clone.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/builtin/clone.c b/builtin/clone.c
index 08d913d306..d397fd36b2 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -220,7 +220,8 @@ static void copy_alternates(struct strbuf *src, const char *src_repo)
 	fclose(in);
 }
 
-static void collect_alternates(struct strvec *alternates)
+static void collect_alternates(struct strvec *alternates,
+			       const char *local_source_repo)
 {
 	if (option_required_reference.nr || option_optional_reference.nr) {
 		struct collect_alternates_data data = {
@@ -234,6 +235,16 @@ static void collect_alternates(struct strvec *alternates)
 		for_each_string_list(&option_optional_reference,
 				     collect_one_alternate, &data);
 	}
+
+	if (local_source_repo) {
+		struct strbuf commondir = STRBUF_INIT;
+
+		get_common_dir(&commondir, local_source_repo);
+		if (option_shared)
+			strvec_pushf(alternates, "%s/objects", commondir.buf);
+
+		strbuf_release(&commondir);
+	}
 }
 
 static void mkdir_if_missing(const char *pathname, mode_t mode)
@@ -357,13 +368,7 @@ static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest,
 
 static void clone_local(const char *src_repo, const char *dest_repo)
 {
-	if (option_shared) {
-		struct strbuf alt = STRBUF_INIT;
-		get_common_dir(&alt, src_repo);
-		strbuf_addstr(&alt, "/objects");
-		odb_add_to_alternates_file(the_repository->objects, alt.buf);
-		strbuf_release(&alt);
-	} else {
+	if (!option_shared) {
 		struct strbuf src = STRBUF_INIT;
 		struct strbuf dest = STRBUF_INIT;
 		get_common_dir(&src, src_repo);
@@ -1348,7 +1353,7 @@ int cmd_clone(int argc,
 		warning(_("--local is ignored"));
 
 	create_object_database(the_repository);
-	collect_alternates(&alternates);
+	collect_alternates(&alternates, is_local ? path : NULL);
 
 	for (size_t i = 0; i < alternates.nr; i++)
 		odb_add_to_alternates_file(the_repository->objects, alternates.v[i]);

-- 
2.55.0.1074.ge7621b4bad.dirty