Description:
------------
When using a custom error handler, it is possible to make PHP trigger an 
E_FATAL by concatenating an object with a __toString() method together 
with a variable that is not set.

Tested in 5.2.9 and 5.2.10.

Reproduce code:
---------------
<?php

class test {

	public static function error_handler($code, $error, $file = NULL, $line = NULL)
	{
		// This error is not suppressed by current error reporting settings
		throw new ErrorException($error, $code, 0, $file, $line);
	}

	public static function run()
	{
		$object = new self;

		echo $object.$foo;
	}

	public function __toString()
	{
		return __CLASS__;
	}

}

error_reporting(E_ALL);

set_error_handler(array('test', 'error_handler'));

test::run();

Expected result:
----------------
PHP Fatal error:  Uncaught exception 'ErrorException' with message 
'Undefined variable: foo' in php_bug.php:15
Stack trace:
#0 php_bug.php(15): test::error_handler()
#1 php_bug.php(29): test::run()
#2 {main}
  thrown in php_bug.php on line 15

Actual result:
--------------
PHP Fatal error:  Method test::__toString() must not throw an exception 
in