1--TEST-- 2Returned null, expected array reference 3--FILE-- 4<?php 5function &foo(array &$in) : array { 6 return null; 7} 8 9$array = [1, 2, 3]; 10var_dump(foo($array)); 11--EXPECTF-- 12Fatal error: Uncaught TypeError: Return value of foo() must be of the type array, null returned in %s:%d 13Stack trace: 14#0 %s(%d): foo(Array) 15#1 {main} 16 thrown in %s on line %d 17