1--TEST-- 2Closure 012: Undefined lexical variables 3--FILE-- 4<?php 5$lambda = function () use ($i) { 6 return ++$i; 7}; 8$lambda(); 9$lambda(); 10var_dump($i); 11$lambda = function () use (&$i) { 12 return ++$i; 13}; 14$lambda(); 15$lambda(); 16var_dump($i); 17?> 18--EXPECTF-- 19Warning: Undefined variable $i in %s on line %d 20 21Warning: Undefined variable $i in %s on line %d 22NULL 23int(2) 24