revision: fix leaking saved parents

The `saved_parents` slab is used by `--full-diff` to save parents of a
commit which we are about to rewrite. We do not release its contents
once it's not used anymore, causing a memory leak. Plug it.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

revision.c

@@ -4207,10 +4207,18 @@ static void save_parents(struct rev_info *revs, struct commit *commit)
 		*pp = EMPTY_PARENT_LIST;
 }
 
+static void free_saved_parent(struct commit_list **parents)
+{
+	if (*parents != EMPTY_PARENT_LIST)
+		free_commit_list(*parents);
+}
+
 static void free_saved_parents(struct rev_info *revs)
 {
-	if (revs->saved_parents_slab)
-		clear_saved_parents(revs->saved_parents_slab);
+	if (!revs->saved_parents_slab)
+		return;
+	deep_clear_saved_parents(revs->saved_parents_slab, free_saved_parent);
+	FREE_AND_NULL(revs->saved_parents_slab);
 }
 
 struct commit_list *get_saved_parents(struct rev_info *revs, const struct commit *commit)

t/t6012-rev-list-simplify.sh

@@ -5,6 +5,7 @@ test_description='merge simplification'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 note () {