Bug #67385 [Nab]: Static property value on trait copied to object if set before class definition.

Edit report at https://bugs.php.net/bug.php?id=67385&edit=1 ID: 67385 User updated by: arjen at react dot com Reported by: arjen at react dot com Summary: Static property value on trait copied to object if set before class definition. Status: Not a bug Type: Bug Package: Scripting Engine problem Operating System: Linux PHP Version: 5.5.13 Block user comment: N Private report: N New Comment: Description: Static property value on trait copied to object if set before class definition. Test script: http://3v4l.org/nP4Pj or <?php trait A { protected static $_a; public static function setA($a) { static::$_a = $a; } public static function getA() { return static::$_a; } } class B { use A; public function __construct() { var_dump(static::$_a); } } A::setA('AAAA'); class C { use A; public function __construct() { var_dump(static::$_a); } } class D extends B {} new B; new C; new D; Expected result: NULL NULL NULL Actual result: NULL string(4) "AAAA" NULL Exactly, traits are not inheritance, so C should not inherit the static properties of trait A, just like B doesn't. One would expect traits to be 'mixed' into a class at compile time, not runtime so the order of definition shouldn't matter (from https://wiki.php.net/rfc/horizontalreuse#traits_composed_from_traits) Consider this test script http://3v4l.org/Oqrgt (slightly modified from https://wiki.php.net/rfc/horizontalreuse#static_variables) Counter::inc is now a static method, called once before C1 and C2 are defined. Both C1 and C2 'inherit' the incremented value from the Counter trait. This clashes with "The flattening property implies that all methods are independent from each other at their usage point, even so, they might origin from the same method/trait." from the trait RFC. Looks like this is related to https://bugs.php.net/bug.php?id=63454 where you commented "Seems like a bug: the order of class declarations and var_dumps matters." Previous Comments: ------------------------------------------------------------------------ [2014-06-05 17:21:56] requinix@php.net Traits are not inheritance. B was composed of trait A before $_a was set. C came after it was set. Next time please follow the instructions for creating bug reports. Posting a link for the description and test script is not enough. http://bugs.php.net/how-to-report.php ------------------------------------------------------------------------ [2014-06-05 13:31:53] arjen at react dot com Description: ------------ See http://3v4l.org/nP4Pj Test script: --------------- See http://3v4l.org/nP4Pj ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=67385&edit=1