Bug #78455 [Nab]: Access violation of private trait members

Edit report at https://bugs.php.net/bug.php?id=78455&edit=1 ID: 78455 Updated by: requinix@php.net Reported by: developmenthero at gmail dot com Summary: Access violation of private trait members Status: Not a bug Type: Bug Package: Scripting Engine problem Operating System: Windows 10 PHP Version: 7.3.8 Block user comment: N Private report: N New Comment: Oh, just noticed it's __get in this new stuff, not __set. So correction: > var_dump($B->value); Would not be valid because B::$value is private so you cannot access it outside the class, but you have __get() so it will intercept the property access and return the string that it does. Previous Comments: ------------------------------------------------------------------------ [2019-08-25 00:14:26] requinix@php.net > Shouldn't it be possible to access private fields of traits from a different scope than > the trait itself? First thing to understand is that the trait isn't some special form of class. Nor is it a set of rules like an interface. It's a bunch of things that PHP will copy and paste into whatever class wants to use it. No really. It's sometimes described as "language-assisted copy and paste" because that's an accurate description of how it works. A's "private $value = 1;" is copied and pasted into B, and B ends up with its very own "private $value = 1;" Same for getValue() and __set(). So > var_dump($B->getValue()); Valid. You're calling B::getValue() which tries to access B::$value which is perfectly fine. > var_dump($B->value); Not valid. B::$value is private so you cannot access it outside the class. ------------------------------------------------------------------------ [2019-08-25 00:03:15] developmenthero at gmail dot com Interestingly i just realized that __get won't be called from inside child-classes, since i upgraded from 7.2.4 to 7.3.7(now /.3.8). But clarify: Shouldn't it be possible to access private fields of traits from a different scope than the trait itself? Pardon me, i stripped down the snippet: <?php declare(strict_types=1); trait A { private $value = 1; public function getValue() { return $this->value; } public function __get($name) { return "hello world"; } } class B { use A; public function getValue() { return $this->value; } } $B = new B(); var_dump($B->getValue()); var_dump($B->value); ------------------------------------------------------------------------ [2019-08-24 23:20:25] requinix@php.net Thank you for this bug report. To properly diagnose the problem, we need a short but complete example script to be able to reproduce this bug ourselves. A proper reproducing script starts with <?php and ends with ?>, is max. 10-20 lines long and does not require any external resources such as databases, etc. If the script requires a database to demonstrate the issue, please make sure it creates all necessary tables, stored procedures etc. Please avoid embedding huge scripts into the report. > Prior to v7.3, "A::__set()" would be triggered here. Nope. https://3v4l.org/5XSGH ------------------------------------------------------------------------ [2019-08-24 23:17:14] developmenthero at gmail dot com Description: ------------ Private members of traits are (at least) since v7.3.7 accessible from within "using" classes now. Unfortunately this broke triggering __get() and __set() methods within traits. Test script: --------------- trait A { private $value = 1; public function getValue() { return $this->value; } public function __set($name, $val) { var_dump($name, $val); } } class B { use A; public function setValue($value) { // Prior to v7.3, "A::__set()" would be triggered here. $this->value = $value; } } $B = new B(); var_dump($B->getValue()); $B->setValue(12); var_dump($B->getValue()); ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=78455&edit=1