Description:
------------
It happens whenever PHP encounters some kind of error message. It tries to print an error message, which apparently requires charset conversion, which triggers a warning about unsupported charset, and it tries to convert encoding again, and so on.

GDB Backtrace: https://pastebin.com/7u96Z8HE


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

// the following invalid line prints error (expected)
asdf


// this one segfaults at the 2nd line
ini_set('default_charset', "EUC-KR");
@ini_set('mbstring.internal_encoding', "EUC-KR");

Expected result:
----------------
Print error, or actually suppress the deprecated warning since it has "@"

Actual result:
--------------
Segfault