I'm sure you can come up with a load of nasty things you can do with $GLOBALS, but what do you want us to do about it? Disable $GLOBALS for use with array_* functions (it that's even possible)? Disable $GLOBALS at all?

I have talked to Zeev about this issues. Asked them may I have to fill bug report and he said:
"They should either use hash_apply(), which automatically protects against 
recursion, or implement the recursion protection themselves (like print_r() 
does).  You can/should open bug reports about them..."
In the start Zeev talks about some functions that have problems with $GLOBALS and arrays that holds elements pointing ot itself.

streplace('them','him',$previous_vote);

OK. status -> open

Your second example isn't like the first.  $a[0] is a reference to itself.  The first bonks because $GLOBALS['GLOBALS'] is a reference to $GLOBALS.  An equivalent is:

<?php
$a=array(1,2,3);
$a[3]=&$a;
array_merge_recursive($a,$a);
var_dump($a);
?>

which will produce the same results.  I'm submitting a feature request for array_recurse_safe($array) which returns an array with no infinite loops.

Oops, forgot to include the link:

http://bugs.php.net/bug.php?id=17279

This bug has been fixed in CVS.

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