Description:
------------
As has been pointed out by Nikita[1], as of PHP 7.0.0 zval_dtor()
is actually the same as zval_ptr_dtor_nogc(). Therefore
preg_match() and some other PCRE functions may leak memory if
objects are passed as $matches and $count, respectively.

[1] <http://news.php.net/php.internals/97197>


Test script:
---------------
<?php

$obj = new stdClass;
$obj->obj = $obj;
preg_match('/./', 'x', $obj);

$obj = new stdClass;
$obj->obj = $obj;
preg_replace('/./', '', 'x', -1, $obj);

$obj = new stdClass;
$obj->obj = $obj;
preg_replace_callback('/./', 'array_merge', 'x', -1, $obj);

$obj = new stdClass;
$obj->obj = $obj;
preg_replace_callback_array(['/./' => 'array_merge'], 'x', -1, $obj);

$obj = new stdClass;
$obj->obj = $obj;
preg_filter('/./', '', 'x', -1, $obj);


Actual result:
--------------
[Sat Nov 26 14:03:38 2016]  Script:  '/vagrant/leak.php'
/vagrant/php-src/Zend/zend_objects.c(162) :  Freeing 0x7FF12465ECD0 (40 bytes), script=/vagrant/leak.php
Last leak repeated 4 times
=== Total 5 memory leaks detected ===