Bug #65903 [Opn]: Reference type property unexpectedly converted to value type property

Edit report at https://bugs.php.net/bug.php?id=65903&edit=1 ID: 65903 Updated by: cmb@php.net Reported by: veg at tut dot by Summary: Reference type property unexpectedly converted to value type property Status: Open Type: Bug Package: Scripting Engine problem Operating System: Windows 7 Pro SP1 x86 PHP Version: 5.5.4 Block user comment: N Private report: N New Comment: JFTR: the behavior has been changed as of PHP 7.0.0, see <https://3v4l.org/VTJMI> and <https://3v4l.org/oi75J>. Previous Comments: ------------------------------------------------------------------------ [2013-10-15 22:07:43] bwoebi@php.net Some simpler reproduce case (also reproducible with arrays etc.): root# php -r '$z = (object)["p" => 1]; $z->p = &$z->p; var_dump($z);' object(stdClass)#1 { ["p"]=> &long(1) // << here is an & } root# php -r '$z = (object)["p" => 1]; $z->p = &$z->p; $z->p; var_dump($z);' object(stdClass)#1 { ["p"]=> long(1) // << note that there's no & } So it seems that a reference to itself on object properties is removed upon direct read access. (The problem is that when referencing a variable to itself the refcount isn't incremented and when a temporary variable is being destroyed the refcount is decremented and now equal to 1; so the reference is thought to be unset and then removed. Note that this only is the case for IS_TMP_VAR (IS_CV and IS_VAR are immune against that).) ------------------------------------------------------------------------ [2013-10-15 19:09:24] veg at tut dot by Description: ------------ I've used a little code snippet to convert property from value type to reference type. It's described here: http://www.php.net/manual/en/language.oop5.cloning.php It's very useful practice when you want to share some properties between all clones. But it works with some bugs. When you try to read a reference type property of object without clones, this property unexpectedly converted to value type property. Test script: --------------- <?php header('content-type: text/plain; charset=utf-8'); class demo { public $n = 0; function __construct() { $this->n =& $this->n; } function magic() { if ($this->n) return; } function set($n) { $this->n = $n; } } // Outputs 1 = 1 as expected $a1 = new demo(); $b1 = clone $a1; $a1->magic(); $b1->set(1); echo "{$a1->n} = {$b1->n}\n"; // Outputs 0 = 1 (magic() method is called a little earlier) $a2 = new demo(); $a2->magic(); $b2 = clone $a2; $b2->set(1); echo "{$a2->n} = {$b2->n}\n"; Expected result: ---------------- 1 = 1 1 = 1 Actual result: -------------- 1 = 1 0 = 1 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=65903&edit=1