pack-bitmap[-write]: use `object_array_clear()`, don't leak

Instead of setting the fields of rev->pending to 0/NULL, thereby leaking
memory, call `object_array_clear(&rev->pending)`.

In pack-bitmap.c, we make copies of those fields as `pending_nr` and
`pending_e`. We never update the aliases and the original fields never
change, so the aliases are not really needed and just make it harder
than necessary to understand the code. While we're here, remove the
aliases to make the code easier to follow.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pack-bitmap-write.c

@@ -297,9 +297,7 @@ void bitmap_writer_build(struct packing_data *to_pack)
 
 			traverse_commit_list(&revs, show_commit, show_object, base);
 
-			revs.pending.nr = 0;
-			revs.pending.alloc = 0;
-			revs.pending.objects = NULL;
+			object_array_clear(&revs.pending);
 
 			stored->bitmap = bitmap_to_ewah(base);
 			need_reset = 0;

pack-bitmap.c

@@ -653,8 +653,6 @@ static int in_bitmapped_pack(struct object_list *roots)
 int prepare_bitmap_walk(struct rev_info *revs)
 {
 	unsigned int i;
-	unsigned int pending_nr = revs->pending.nr;
-	struct object_array_entry *pending_e = revs->pending.objects;
 
 	struct object_list *wants = NULL;
 	struct object_list *haves = NULL;
@@ -669,8 +667,8 @@ int prepare_bitmap_walk(struct rev_info *revs)
 			return -1;
 	}
 
-	for (i = 0; i < pending_nr; ++i) {
-		struct object *object = pending_e[i].item;
+	for (i = 0; i < revs->pending.nr; ++i) {
+		struct object *object = revs->pending.objects[i].item;
 
 		if (object->type == OBJ_NONE)
 			parse_object_or_die(&object->oid, NULL);
@@ -714,9 +712,7 @@ int prepare_bitmap_walk(struct rev_info *revs)
 	if (!bitmap_git.loaded && load_pack_bitmap() < 0)
 		return -1;
 
-	revs->pending.nr = 0;
-	revs->pending.alloc = 0;
-	revs->pending.objects = NULL;
+	object_array_clear(&revs->pending);
 
 	if (haves) {
 		revs->ignore_missing_links = 1;