Description:
------------
Valgrind output:

~/dev/php-src$ ./leak-check.sh t72.php 
==31421== Memcheck, a memory error detector
==31421== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==31421== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==31421== Command: sapi/cli/php t72.php
==31421== 
int(6)
==31421== 
==31421== HEAP SUMMARY:
==31421==     in use at exit: 180 bytes in 7 blocks
==31421==   total heap usage: 14,479 allocs, 14,472 frees, 1,478,806 bytes allocated
==31421== 
==31421== 144 bytes in 6 blocks are definitely lost in loss record 2 of 2
==31421==    at 0x402BE68: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==31421==    by 0x8440E25: _emalloc (zend_alloc.c:2438)
==31421==    by 0x8468C0B: zend_call_function (zend_execute_API.c:815)
==31421==    by 0x8333833: zif_array_reduce (array.c:4305)
==31421==    by 0x84C39BC: ZEND_DO_FCALL_SPEC_HANDLER (zend_vm_execute.h:595)
==31421==    by 0x84C2D16: execute_ex (zend_vm_execute.h:354)
==31421==    by 0x84C2ECA: zend_execute (zend_vm_execute.h:383)
==31421==    by 0x847FC4F: zend_execute_scripts (zend.c:1319)
==31421==    by 0x83D9C4C: php_execute_script (main.c:2564)
==31421==    by 0x852CE63: do_cli (php_cli.c:980)
==31421==    by 0x852E217: main (php_cli.c:1358)
==31421== 
==31421== LEAK SUMMARY:
==31421==    definitely lost: 144 bytes in 6 blocks
==31421==    indirectly lost: 0 bytes in 0 blocks
==31421==      possibly lost: 0 bytes in 0 blocks
==31421==    still reachable: 36 bytes in 1 blocks
==31421==         suppressed: 0 bytes in 0 blocks
==31421== Reachable blocks (those to which a pointer was found) are not shown.
==31421== To see them, rerun with: --leak-check=full --show-reachable=yes
==31421== 
==31421== For counts of detected and suppressed errors, rerun with: -v
==31421== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)


Test script:
---------------
<?php
$array = [1, 2, 3];
var_dump(array_reduce($array, function(&$a, &$b) {
    return $a + $b;
}, 0));