[2014-09-29 15:30 UTC] rasmus@php.net

Description:
------------
PHP 5.5 introduced a new undefined property notice for this case:

$a->undefined .= 'test';

This means that if a custom error handler is in place it will be triggered, of course. There is a weird side-effect that can happen if the error handler hits the same error causing the property name to be overwritten. eg.

http://3v4l.org/KGXhF

Compare to:

http://3v4l.org/VPmLK

PHP 5.6 and PHP 7 are affected as well.

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

class test {
    public function __construct() {
        $this->test = 'meow';
    }
}
 
function error_handler() {
    $test = new test();
    return true;
}
 
set_error_handler("error_handler");
 
// test one
class a {}
$a = new a;
$a->undefined .= 'test';
echo isset($a->undefined) ? 'true' : 'false';
 
echo "\n";
 
// test two
$b .= 'test';
echo isset($b) ? 'true' : 'false';
 
echo "\n";


Expected result:
----------------
true
true

Actual result:
--------------
false
true