1 files changed, 15 insertions, 31 deletions

diff --git a/Zend/zend_inheritance.c b/Zend/zend_inheritance.c
index 70e2dcdfd4..dca0f555cb 100644
--- a/Zend/zend_inheritance.c
+++ b/Zend/zend_inheritance.c
@@ -183,10 +183,16 @@ static zend_always_inline zend_bool zend_iterable_compatibility_check(zend_arg_i
 }
 /* }}} */
 
-static int zend_do_perform_type_hint_check(const zend_function *fe, zend_arg_info *fe_arg_info, const zend_function *proto, zend_arg_info *proto_arg_info) /* {{{ */
+static int zend_perform_covariant_type_check(
+		const zend_function *fe, zend_arg_info *fe_arg_info,
+		const zend_function *proto, zend_arg_info *proto_arg_info) /* {{{ */
 {
 	ZEND_ASSERT(ZEND_TYPE_IS_SET(fe_arg_info->type) && ZEND_TYPE_IS_SET(proto_arg_info->type));
 
+	if (ZEND_TYPE_ALLOW_NULL(fe_arg_info->type) && !ZEND_TYPE_ALLOW_NULL(proto_arg_info->type)) {
+		return 0;
+	}
+
 	if (ZEND_TYPE_IS_CLASS(fe_arg_info->type) && ZEND_TYPE_IS_CLASS(proto_arg_info->type)) {
 		zend_string *fe_class_name, *proto_class_name;
 		const char *class_name;
@@ -239,6 +245,10 @@ static int zend_do_perform_type_hint_check(const zend_function *fe, zend_arg_inf
 		zend_string_release(proto_class_name);
 		zend_string_release(fe_class_name);
 	} else if (ZEND_TYPE_CODE(fe_arg_info->type) != ZEND_TYPE_CODE(proto_arg_info->type)) {
+		if (ZEND_TYPE_CODE(proto_arg_info->type) == IS_ITERABLE) {
+			return zend_iterable_compatibility_check(fe_arg_info);
+		}
+
 		/* Incompatible built-in types */
 		return 0;
 	}
@@ -259,7 +269,9 @@ static int zend_do_perform_arg_type_hint_check(const zend_function *fe, zend_arg
 		return 0;
 	}
 
-	return zend_do_perform_type_hint_check(fe, fe_arg_info, proto, proto_arg_info);
+	/* Contravariant type check is performed as a covariant type check with swapped
+	 * argument order. */
+	return zend_perform_covariant_type_check(proto, proto_arg_info, fe, fe_arg_info);
 }
 /* }}} */
 
@@ -332,21 +344,6 @@ static zend_bool zend_do_perform_implementation_check(const zend_function *fe, c
 		}
 
 		if (!zend_do_perform_arg_type_hint_check(fe, fe_arg_info, proto, proto_arg_info)) {
-			switch (ZEND_TYPE_CODE(fe_arg_info->type)) {
-				case IS_ITERABLE:
-					if (!zend_iterable_compatibility_check(proto_arg_info)) {
-						return 0;
-					}
-					break;
-
-				default:
-					return 0;
-			}
-		}
-
-		// This introduces BC break described at https://bugs.php.net/bug.php?id=72119
-		if (ZEND_TYPE_IS_SET(proto_arg_info->type) && ZEND_TYPE_ALLOW_NULL(proto_arg_info->type) && !ZEND_TYPE_ALLOW_NULL(fe_arg_info->type)) {
-			/* incompatible nullability */
 			return 0;
 		}
 
@@ -364,20 +361,7 @@ static zend_bool zend_do_perform_implementation_check(const zend_function *fe, c
 			return 0;
 		}
 
-		if (!zend_do_perform_type_hint_check(fe, fe->common.arg_info - 1, proto, proto->common.arg_info - 1)) {
-			switch (ZEND_TYPE_CODE(proto->common.arg_info[-1].type)) {
-				case IS_ITERABLE:
-					if (!zend_iterable_compatibility_check(fe->common.arg_info - 1)) {
-						return 0;
-					}
-					break;
-
-				default:
-					return 0;
-			}
-		}
-
-		if (ZEND_TYPE_ALLOW_NULL(fe->common.arg_info[-1].type) && !ZEND_TYPE_ALLOW_NULL(proto->common.arg_info[-1].type)) {
+		if (!zend_perform_covariant_type_check(fe, fe->common.arg_info - 1, proto, proto->common.arg_info - 1)) {
 			return 0;
 		}
 	}