PHP Bug: An object is automatically created if an unset object with a property is passed by reference. Inconsistent warnings depending on the variable type.

php_bug_unset_object_property_by_reference.php

<?php

// Possible PHP Bug:
// An object is automatically created if an unset object with a property is passed by reference
// Inconsistent Warnings depending on the variable type

// Live test http://codepad.viper-7.com/ueZkz4
// Possibly related PHP bug https://bugs.php.net/bug.php?id=52237



// isset()

var_dump(isset($unset->property)); // FALSE

var_dump(isset($unset)); // FALSE
var_dump(is_object($unset)); // FALSE 
var_dump(property_exists($unset, 'property')); // NULL
var_dump($unset->property); // NULL

$unset = FALSE;

var_dump(isset($unset->property)); // FALSE

unset($unset);



// isset_or()

function isset_or(&$var, $or = NULL)
{
	return isset($var)? $var : $or;
}

var_dump(isset_or($unset->property)); // NULL, but... the $unset object is automagically created when passing by reference an unset variable with a property !?

var_dump(isset($unset)); // TRUE
var_dump(is_object($unset)); // TRUE
var_dump(property_exists($unset, 'property')); // TRUE
var_dump($unset->property); // NULL

$unset = NULL;
var_dump(isset_or($unset->property)); // NULL, no Warning

$unset = FALSE;
var_dump(isset_or($unset->property)); // NULL, no Warning

$unset = 0;
var_dump(isset_or($unset->property)); // NULL, Warning: Attempt to modify property of non-object

$unset = '';
var_dump(isset_or($unset->property)); // NULL, no Warning

$unset = array();
var_dump(isset_or($unset->property)); // NULL, Warning: Attempt to modify property of non-object