Description:
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When using undefined variable in ?: php generate notice

in php 5.2.x very often use this code

$inp = isset($_POST['inp']) ? $_POST['inp'] : 'def_inp';

in php 5.3 want use a shorter code

$inp = $_POST['inp'] ?: 'def_inp';

Reproduce code:
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<?php

$inp = $_POST['inp'] ?: 'def_inp';
echo $inp;

?>

Expected result:
----------------
def_inp

Actual result:
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Notice: Undefined index: inp in /path/to/to/index.php on line 3
def_inp