[PATCH v2 2/5] fsck: support refs pointing to lazy objects

[Jonathan Tan <jonathantanmy@google.com>]

Teach fsck to not treat refs with missing targets as an error when
extensions.lazyobject is set.

For the purposes of warning about no default refs, such refs are still
treated as legitimate refs.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
---
 builtin/fsck.c         |  8 ++++++++
 t/t0410-lazy-object.sh | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/builtin/fsck.c b/builtin/fsck.c
index b7e245654..38ed630d8 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -438,6 +438,14 @@ static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 
 	obj = parse_object(oid);
 	if (!obj) {
+		if (repository_format_lazy_object) {
+			/*
+			 * Increment default_refs anyway, because this is a
+			 * valid ref.
+			 */
+			default_refs++;
+			return 0;
+		}
 		error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
 		errors_found |= ERROR_REACHABLE;
 		/* We'll continue with the rest despite the error.. */
diff --git a/t/t0410-lazy-object.sh b/t/t0410-lazy-object.sh
index 36442531f..00e1b4a88 100755
--- a/t/t0410-lazy-object.sh
+++ b/t/t0410-lazy-object.sh
@@ -29,4 +29,24 @@ test_expect_success '...but succeeds if lazyobject is set' '
 	git -C repo fsck
 '
 
+test_expect_success 'fsck fails on lazy object pointed to by ref' '
+	rm -rf repo &&
+	test_create_repo repo &&
+	test_commit -C repo 1 &&
+
+	A=$(git -C repo commit-tree -m a HEAD^{tree}) &&
+
+	# Reference $A only from ref, and delete it
+	git -C repo branch mybranch "$A" &&
+	delete_object repo "$A" &&
+
+	test_must_fail git -C repo fsck
+'
+
+test_expect_success '...but succeeds if lazyobject is set' '
+	git -C repo config core.repositoryformatversion 1 &&
+	git -C repo config extensions.lazyobject "arbitrary string" &&
+	git -C repo fsck
+'
+
 test_done
-- 
2.14.0.rc1.383.gd1ce394fe2-goog