Description:
------------
In array_walk_recursive(), if we pass non-existent callback function then it gives following output
1)for PHP 5
Warning: array_walk_recursive(): Unable to call echo() - function does not exist in %s on line %d
bool(true)

    
2)for PHP 6
Warning: array_walk_recursive() : Expects parameter 2 to be valid callback, string given in %s on line %d
NULL

In PHP5, array_walk_recursive() gives warning message the number passed array element times, where as in PHP 6, it gives warning message only once with return value "NULL". This is an inconsistent behavior of array_walk_recursive() with PHP5 and PHP6.


The return value of " bool(true)" in PHP5 (1),  will misguide/confuse the developers as the documentation says array_walk_recursive() returns TRUE on Success and FALSE on Failure.

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

$input = array(array(1,2), array(3), array(4,5));

var_dump( array_walk_recursive($input, 'echo'));

?>


Expected result:
----------------
/***** for PHP5 ****/

Warning: array_walk_recursive(): Unable to call echo() - function does not exist in %s on line %d
bool(false)

/**** for PHP6 ****/
Warning: array_walk_recursive() : Expects parameter 2 to be valid callback, string given in %s on line %d
NULL


Actual result:
--------------
/**** for PHP5 ****/

Warning: array_walk_recursive(): Unable to call echo() - function does not exist in %s on line %d

Warning: array_walk_recursive(): Unable to call echo() - function does not exist in %s on line %d

Warning: array_walk_recursive(): Unable to call echo() - function does not exist in %s on line %d
bool(true)


/**** for PHP6 ****/
Warning: array_walk_recursive() : Expects parameter 2 to be valid callback, string given in %s on line %d
NULL