fsck: support referenced promisor objects

Teach fsck to not treat missing promisor objects indirectly pointed to
by refs as an error when extensions.partialclone is set.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: jonathantanmy

builtin/fsck.c

@@ -149,6 +149,15 @@ static int mark_object(struct object *obj, int type, void *data, struct fsck_opt
 	if (obj->flags & REACHABLE)
 		return 0;
 	obj->flags |= REACHABLE;
+
+	if (is_promisor_object(&obj->oid))
+		/*
+		 * Further recursion does not need to be performed on this
+		 * object since it is a promisor object (so it does not need to
+		 * be added to "pending").
+		 */
+		return 0;
+
 	if (!(obj->flags & HAS_OBJ)) {
 		if (parent && !has_object_file(&obj->oid)) {
 			printf("broken link from %7s %s\n",
@@ -208,6 +217,8 @@ static void check_reachable_object(struct object *obj)
 	 * do a full fsck
 	 */
 	if (!(obj->flags & HAS_OBJ)) {
+		if (is_promisor_object(&obj->oid))
+			return;
 		if (has_sha1_pack(obj->oid.hash))
 			return; /* it is in pack - forget about it */
 		printf("missing %s %s\n", printable_type(obj),

t/t0410-partial-clone.sh

@@ -102,4 +102,27 @@ test_expect_success 'missing ref object, but promised, passes fsck' '
 	git -C repo fsck
 '
 
+test_expect_success 'missing object, but promised, passes fsck' '
+	rm -rf repo &&
+	test_create_repo repo &&
+	test_commit -C repo 1 &&
+	test_commit -C repo 2 &&
+	test_commit -C repo 3 &&
+	git -C repo tag -a annotated_tag -m "annotated tag" &&
+
+	C=$(git -C repo rev-parse 1) &&
+	T=$(git -C repo rev-parse 2^{tree}) &&
+	B=$(git hash-object repo/3.t) &&
+	AT=$(git -C repo rev-parse annotated_tag) &&
+
+	promise_and_delete "$C" &&
+	promise_and_delete "$T" &&
+	promise_and_delete "$B" &&
+	promise_and_delete "$AT" &&
+
+	git -C repo config core.repositoryformatversion 1 &&
+	git -C repo config extensions.partialclone "arbitrary string" &&
+	git -C repo fsck
+'
+
 test_done