merge: convert checkout_fast_forward to struct object_id

Converting checkout_fast_forward is required to convert
parse_tree_indirect.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/merge.c

@@ -1372,8 +1372,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			goto done;
 		}
 
-		if (checkout_fast_forward(head_commit->object.oid.hash,
-					  commit->object.oid.hash,
+		if (checkout_fast_forward(&head_commit->object.oid,
+					  &commit->object.oid,
 					  overwrite_ignore)) {
 			ret = 1;
 			goto done;

builtin/pull.c

@@ -523,7 +523,7 @@ static int pull_into_void(const struct object_id *merge_head,
 	 * index/worktree changes that the user already made on the unborn
 	 * branch.
 	 */
-	if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head->hash, 0))
+	if (checkout_fast_forward(&empty_tree_oid, merge_head, 0))
 		return 1;
 
 	if (update_ref("initial pull", "HEAD", merge_head->hash, curr_head->hash, 0, UPDATE_REFS_DIE_ON_ERR))
@@ -839,7 +839,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 			"fast-forwarding your working tree from\n"
 			"commit %s."), oid_to_hex(&orig_head));
 
-		if (checkout_fast_forward(orig_head.hash, curr_head.hash, 0))
+		if (checkout_fast_forward(&orig_head, &curr_head, 0))
 			die(_("Cannot fast-forward your working tree.\n"
 				"After making sure that you saved anything precious from\n"
 				"$ git diff %s\n"

cache.h

@@ -2198,8 +2198,8 @@ struct commit_list;
 int try_merge_command(const char *strategy, size_t xopts_nr,
 		const char **xopts, struct commit_list *common,
 		const char *head_arg, struct commit_list *remotes);
-int checkout_fast_forward(const unsigned char *from,
-			  const unsigned char *to,
+int checkout_fast_forward(const struct object_id *from,
+			  const struct object_id *to,
 			  int overwrite_ignore);
 
 

merge.c

@@ -44,8 +44,8 @@ int try_merge_command(const char *strategy, size_t xopts_nr,
 	return ret;
 }
 
-int checkout_fast_forward(const unsigned char *head,
-			  const unsigned char *remote,
+int checkout_fast_forward(const struct object_id *head,
+			  const struct object_id *remote,
 			  int overwrite_ignore)
 {
 	struct tree *trees[MAX_UNPACK_TREES];
@@ -79,10 +79,10 @@ int checkout_fast_forward(const unsigned char *head,
 	opts.fn = twoway_merge;
 	setup_unpack_trees_porcelain(&opts, "merge");
 
-	trees[nr_trees] = parse_tree_indirect(head);
+	trees[nr_trees] = parse_tree_indirect(head->hash);
 	if (!trees[nr_trees++])
 		return -1;
-	trees[nr_trees] = parse_tree_indirect(remote);
+	trees[nr_trees] = parse_tree_indirect(remote->hash);
 	if (!trees[nr_trees++])
 		return -1;
 	for (i = 0; i < nr_trees; i++) {

sequencer.c

@@ -382,7 +382,7 @@ static int fast_forward_to(const struct object_id *to, const struct object_id *f
 	struct strbuf err = STRBUF_INIT;
 
 	read_cache();
-	if (checkout_fast_forward(from->hash, to->hash, 1))
+	if (checkout_fast_forward(from, to, 1))
 		return -1; /* the callee should have complained already */
 
 	strbuf_addf(&sb, _("%s: fast-forward"), _(action_name(opts)));