===description===
nonNullableSubclassParam
===file===
<?php
                    class A {
                        public function foo(?string $s): string {
                            return $s !== null ? $s : "hello";
                        }
                    }

                    class B extends A {
                        public function foo(string $s): string {
                            return $s;
                        }
                    }
===expect===
Argument 1 of B::foo has wrong type \
===ignore===
TODO
