1--TEST-- 2bug #71428: Validation type inheritance with = NULL 3--FILE-- 4<?php 5class A { } 6class B { public function m(A $a = NULL, $n) { echo "B.m";} }; 7class C extends B { public function m(A $a , $n) { echo "C.m";} }; 8?> 9--EXPECTF-- 10Warning: Declaration of C::m(A $a, $n) should be compatible with B::m(?A $a, $n) in %sbug71428.3.php on line 4 11