Description:
------------
Passing an undefined variable by reference causes that variable to be implicitly defined. However, this is not the case if the argument is inside parentheses. 

This is reproducible on php5.2.5 as well as php5.3 and php6 snaps.



Reproduce code:
---------------
<?php
function f(&$ref) {
  $ref='changed';
}

echo "Pass undefined variable by ref:\n";
f( $a );
var_dump($a);

echo "\nPass undefined variable by ref with parentheses:\n";
f( ($b) );
var_dump($b);
?>


Expected result:
----------------
Pass undefined variable by ref:
string(7) "changed"

Pass undefined variable by ref with parentheses:
string(7) "changed"

Actual result:
--------------
Pass undefined variable by ref:
string(7) "changed"

Pass undefined variable by ref with parentheses:

Notice: Undefined variable: b in %s on line 11

Strict Standards: Only variables should be passed by reference in %s on line 11

Notice: Undefined variable: b in %s on line 12
NULL