Bug #76725 [Opn->Csd]: Self-referencing constant fatal error in specific case

Edit report at https://bugs.php.net/bug.php?id=76725&edit=1 ID: 76725 Updated by: nikic@php.net Reported by: martin dot ninov at gmail dot com Summary: Self-referencing constant fatal error in specific case -Status: Open +Status: Closed Type: Bug Package: *General Issues Operating System: Ubuntu16.04 and W10 PHP Version: 7.2.8 -Assigned To: +Assigned To: nikic Block user comment: N Private report: N New Comment: This is fixed in PHP 8.1 in that the "namespace" no longer makes a difference, and no error is thrown in either case. The reason was a bug in the compile-time evaluator, which failed to replace self::OTHER during compilation if a namespace was used. However, as said above, whether or not an error gets thrown in this case is unspecified, and the behavior may change in the future. Previous Comments: ------------------------------------------------------------------------ [2018-08-11 14:48:32] a at b dot c dot de Dunno how relevant this is, but in 7.2.8 under Windows 10, it fails when run as a script, but succeeds (and prints "waffles") when entered with -a's interactive shell. ------------------------------------------------------------------------ [2018-08-09 13:24:33] nikic@php.net So generally, the code either failing or not failing is fine in this case. It can fail because that constant declaration is clearly illegal, it can not fail because the constant is not actually used. But there's definitely something fishy going on here. While the impact of the property declaration doesn't surprise me much (probably triggers a full class initializer resolution), I don't see how the namespace declaration should impact this. ------------------------------------------------------------------------ [2018-08-09 13:05:51] martin dot ninov at gmail dot com The bug is that somehow a bunch of unrelated statements cause the code to fail. Also, I misspoke when I said 'constant assignment', I meant the 'property declaration' indeed. ------------------------------------------------------------------------ [2018-08-09 13:01:37] nikic@php.net What exactly is the bug here? That there is no error if the property declaration is removed? ------------------------------------------------------------------------ [2018-08-09 12:57:21] martin dot ninov at gmail dot com Description: ------------ The test script generates a Fatal error: Uncaught Error: Cannot declare self-referencing constant 'self::FOO' All lines of test script are required, except the last line, which is just there to output something. Removing any of the following eliminates the error: namespace second constant constant assignment I tested on a number on both win10 and linux(ubuntu 16.04), and a number of php 7.2 versions. This: https://3v4l.org/3aIHb says it works on php5.6 versions and fails in php7.0+ Test script: --------------- <?php namespace Waffles; abstract class A { const FOO = self::FOO; const OTHER = 0; private $waf = self::OTHER; } class B extends A { const FOO = 'waffles'; } $foo = new B(); echo $foo::FOO; Expected result: ---------------- waffles Actual result: -------------- Fatal error: Uncaught Error: Cannot declare self-referencing constant 'self::FOO' ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=76725&edit=1