1--TEST-- 2callable type#003 3--FILE-- 4<?php 5 6function foo(callable $a, $b, callable $c) { 7 var_dump($a, $b, $c); 8} 9function bar(callable $a = null) { 10 var_dump($a); 11} 12 13foo("strpos", 123, "strpos"); 14bar("substr"); 15?> 16--EXPECTF-- 17Deprecated: bar(): Implicitly marking parameter $a as nullable is deprecated, the explicit nullable type must be used instead in %s on line %d 18string(6) "strpos" 19int(123) 20string(6) "strpos" 21string(6) "substr" 22