ref_newer: convert to use struct object_id

Convert ref_newer and its caller to use struct object_id instead of
unsigned char *.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>
diff --git a/builtin/remote.c b/builtin/remote.c
index 68dec16..6694cf2 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -417,7 +417,7 @@
 		else if (is_null_oid(&ref->old_oid))
 			info->status = PUSH_STATUS_CREATE;
 		else if (has_object_file(&ref->old_oid) &&
-			 ref_newer(ref->new_oid.hash, ref->old_oid.hash))
+			 ref_newer(&ref->new_oid, &ref->old_oid))
 			info->status = PUSH_STATUS_FASTFORWARD;
 		else
 			info->status = PUSH_STATUS_OUTOFDATE;
diff --git a/http-push.c b/http-push.c
index f2db3a6..68ce340 100644
--- a/http-push.c
+++ b/http-push.c
@@ -1886,8 +1886,8 @@
 		    !is_null_oid(&ref->old_oid) &&
 		    !ref->force) {
 			if (!has_object_file(&ref->old_oid) ||
-			    !ref_newer(ref->peer_ref->new_oid.hash,
-				       ref->old_oid.hash)) {
+			    !ref_newer(&ref->peer_ref->new_oid,
+				       &ref->old_oid)) {
 				/*
 				 * We do not have the remote ref, or
 				 * we know that the remote ref is not
diff --git a/remote.c b/remote.c
index 4beebad..bdae86c 100644
--- a/remote.c
+++ b/remote.c
@@ -1590,7 +1590,7 @@
 			else if (!lookup_commit_reference_gently(ref->old_oid.hash, 1) ||
 				 !lookup_commit_reference_gently(ref->new_oid.hash, 1))
 				reject_reason = REF_STATUS_REJECT_NEEDS_FORCE;
-			else if (!ref_newer(ref->new_oid.hash, ref->old_oid.hash))
+			else if (!ref_newer(&ref->new_oid, &ref->old_oid))
 				reject_reason = REF_STATUS_REJECT_NONFASTFORWARD;
 		}
 
@@ -1944,7 +1944,7 @@
 	}
 }
 
-int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
+int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 {
 	struct object *o;
 	struct commit *old, *new;
@@ -1955,12 +1955,12 @@
 	 * Both new and old must be commit-ish and new is descendant of
 	 * old.  Otherwise we require --force.
 	 */
-	o = deref_tag(parse_object(old_sha1), NULL, 0);
+	o = deref_tag(parse_object(old_oid->hash), NULL, 0);
 	if (!o || o->type != OBJ_COMMIT)
 		return 0;
 	old = (struct commit *) o;
 
-	o = deref_tag(parse_object(new_sha1), NULL, 0);
+	o = deref_tag(parse_object(new_oid->hash), NULL, 0);
 	if (!o || o->type != OBJ_COMMIT)
 		return 0;
 	new = (struct commit *) o;
diff --git a/remote.h b/remote.h
index 163ea5e..4a039ba 100644
--- a/remote.h
+++ b/remote.h
@@ -150,7 +150,7 @@
 				     struct sha1_array *shallow);
 
 int resolve_remote_symref(struct ref *ref, struct ref *list);
-int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1);
+int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid);
 
 /*
  * Remove and free all but the first of any entries in the input list