Description:
------------
Upgrading from PHP 5.1.6-1 (Debian) to 5.2.1 (Ubuntu) a regression has appeared in array_diff().  Comparisons now fail when an array member is a stdClass object.

Also reproduced with 5.2.4RC1-dev.

Reproduce code:
---------------
<?php
$dogs = array();
$poodle = new stdClass;
$poodle->collar = 'red';
array_push($dogs, $poodle);
array_push($dogs, 'terrier');
array_push($dogs, 'dalmation');

$cat = array('persian' => array(1, 2, 3));

var_dump(array_diff($dogs, $cat));
?>


Expected result:
----------------
array(3) {
  [0]=>
  object(stdClass)#1 (1) {
    ["collar"]=>
    string(3) "red"
  }
  [1]=>
  string(7) "terrier"
  [2]=>
  string(9) "dalmation"
}


Actual result:
--------------
Catchable fatal error: Object of class stdClass could not be converted to string in /miru/home/steve-o/- on line 11