Description:
------------
We found a bug that leads to memory leak in php interpreter. Here's the log:
---
~/php-src/bld/sapi/cli/php -f php_poc41.php

Warning: Undefined variable $b in /home/yongheng/php_commit/php_poc41.php on line 4

Fatal error: Uncaught TypeError: Illegal offset type in /home/yongheng/php_commit/php_poc41.php:4
Stack trace:
#0 {main}
  thrown in /home/yongheng/php_commit/php_poc41.php on line 4
[Sun Aug  9 17:17:48 2020]  Script:  '/home/yongheng/php_commit/php_poc41.php'
/home/yongheng/php-src/Zend/zend_hash.c(278) :  Freeing 0x00007fddefa58540 (56 bytes), script=/home/yongheng/php_commit/php_poc41.php
[Sun Aug  9 17:17:48 2020]  Script:  '/home/yongheng/php_commit/php_poc41.php'
/home/yongheng/php-src/Zend/zend_hash.c(153) :  Freeing 0x00007fddefa5c3c0 (264 bytes), script=/home/yongheng/php_commit/php_poc41.php
=== Total 2 memory leaks detected ===
---

Test script:
---------------
<?
$a = array () ;
try {
    $b [ $a ] -= array ( $a ) ;
}
catch ( c ) {  }