Bug #74509 [Opn->Nab]: array_shift($foo) throws "null given" instead of "Undefined variable"

Edit report at https://bugs.php.net/bug.php?id=74509&edit=1 ID: 74509 Updated by: requinix@php.net Reported by: pov at fingerprint dot fr Summary: array_shift($foo) throws "null given" instead of "Undefined variable" -Status: Open +Status: Not a bug Type: Bug -Package: PHP Language Specification +Package: Variables related PHP Version: 5.6.30 Block user comment: N Private report: N New Comment: All those functions have one thing in common: the argument is by reference. PHP does not issue warnings when creating references to variables that do not exist, which is why code like function add($a, $b, &$c) { $c = $a + $b; } add(1, 2, $sum); works without problems. Changing that as a whole would create many warnings out of nowhere for use cases that were easily justifiable before. The alternative would be a number of tweaks throughout PHP to make (some) functions that use references warn if the variable did not already exist, but given that the purpose would be to turn a clear E_WARNING into the less severe (and often ignored) E_NOTICE, I don't think doing so is worth it. Previous Comments: ------------------------------------------------------------------------ [2017-04-28 16:15:03] pov at fingerprint dot fr Description: ------------ When applying array_shift on a non-existing variable, a warning about array_shift is emitted (array_shift() expects parameter 1 to be array, null given) instead of a notice on the non-existing variable. Tested on all the following packaged versions : 7.0.17-2+deb.sury.org~trusty+1 7.1.3-2+deb.sury.org~trusty+1 5.5.38-4+deb.sury.org~trusty+1 5.6.30-7+deb.sury.org~trusty+1 -- Additional tests This bug probably applies on other functions as well. Some tests gives interesting results (I note NUV = Notice : Undefined variable - ok -, WNG = Warning : null given - which shouldn't be) : array_shift($foo) WNG array_slice($foo) NUV array_unshift($foo, 1) WNG array_unshift($foo, $bar) NUV bar (logically, should be NUV $foo first) array_pop($foo) WNG array_sum($foo) NUV empty($foo) returns true htmlentities($foo) NUV Test script: --------------- error_reporting(E_ALL | E_NOTICE); ini_set('display_errors', true); echo '$foo = '; echo $foo; echo "\n"; echo 'array_shift($foo) = '; echo array_shift($foo); echo "\n"; exit; Expected result: ---------------- $foo = Notice: Undefined variable: foo in index.php on line 4 array_shift($foo) = Notice: Undefined variable: foo in index.php on line 4 Actual result: -------------- $foo = Notice: Undefined variable: foo in index.php on line 4 array_shift($foo) = Warning: array_shift() expects parameter 1 to be array, null given in index.php on line 5 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=74509&edit=1