in_array() related problem

Hello all, I'm new to this list. To not flooding the bug tracking system I hope to clarify some of my understanding here. I am referring to the (now bogus) bug report http://bugs.php.net/bug.php?id=39356&edit=2. This happens after my upgrade to PHP 5.2, where the code shown produces a "Fatal error: Nesting level too deep - recursive dependency?". Same testing code reproduced below: ---------------------------- <?php class A { public $b; } class B { public $a; } $a = new A; $b = new B; $b->a = $a; $a->b = $b; $test = array($a, $b); var_dump(in_array($a, $test)); ---------------------------- I think this is not rare for a child item to have knowledge about its parent, forming a cross-reference. This code runs with no problem in PHP5.1.6, but not in 5.2. Ilia kindly points out that "In php 5 objects are passed by reference, so your code does in fact create a circular dependency.". I know the passed by reference rule. What I'm now puzzled is, why this should lead to an error. To my knowledge, despite the type-casting issue and actual algorithm, in_array() should actually do nothing more than: function mimic_in_array($search, $list) { foreach ($list as $item) if ($search == $item)

     return true;

return false; } Which means: 1. in_array() isn't multi-dimensional. 2. in_array() doesn't care about the properties of any object. That is, I don't expect in_array() to nest through all available inner arrays for a match, not to mention those are object properties, not arrays. So here is the question: Why should in_array() throws such a "Fatal error: Nesting level too deep" error? Why should it care? Is there any behaviour I don't know? Thanks all in advance. Tamcy