Bug #74450 [Opn->Csd]: Fetching the value of a constant triggers inconsistent behaviour

Edit report at https://bugs.php.net/bug.php?id=74450&edit=1 ID: 74450 Updated by: cmb@php.net Reported by: diego dot bindart at gmail dot com Summary: Fetching the value of a constant triggers inconsistent behaviour -Status: Open +Status: Closed Type: Bug Package: Apache2 related Operating System: Linux Mint 18 PHP Version: 7.0.18 -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: Case-insensitive constans are deprecated as of PHP 7.3.0 and removed as of PHP 8.0.0, so this ticket is obsolete. Previous Comments: ------------------------------------------------------------------------ [2017-04-15 21:44:23] nikic@php.net Also, I believe that the reason why we're currently not checking for this, is that while the direction case-insensitive -> case-sensitive is simple (we can check whether the lower-cased variant exists when defining the case-sensitive constant), the direction case-sensitive -> case-insensitive is not (we cannot check whether a case-variant exists, without storing additional information.) This is probably a good time to create an RFC for deprecation and removal of case-insensitive constants (with null/true/false special-cased). Notably HHVM already doesn't support them, which tells us that at least no open-source software of any significance makes use of them. ------------------------------------------------------------------------ [2017-04-15 21:37:04] nikic@php.net The reason you're seeing this specific behavior is a combination of runtime caching and literal compaction. You're seeing this only with Apache, because that's where you have opcache enabled, which performs the deduplication. Here is a way to reproduce this without opcache as well: https://3v4l.org/L6nCp Anyway, I believe the bug here is that we currently do not check whether a case-insensitive constant with the same name already exists. This should be giving a "constant already defined" error instead. ------------------------------------------------------------------------ [2017-04-15 21:30:53] diego dot bindart at gmail dot com Editted the title to make the issue clearer ------------------------------------------------------------------------ [2017-04-15 21:27:50] diego dot bindart at gmail dot com Description: ------------ I define a constant as case-insenstive and then define a capitalization variation of the same constant. In between defines I echo the value of the constant *using the case-sensitive capitalization*. In the CLI it works as expected, but testing in the apache server gives me the right anser only once, and then a different answers on succesive page reloads. The same happens if instead of echoing I assign the constant value to a variable (e.g. $var = SOME_CONST). Tested on Chrome, Opera and Firefox, using Apache 2.4.18 Ubuntu. Steps to reproduce: * execute the code below, as given, in a web server. You should get (as expected): 12 * reload the page (might need to do this several times) and you get instead: 11 ---------------- Other things to note that I tested: * it works as expected in the command line * if you don't echo SOME_CONST before defining the case-sensitive variation, it works as expected * if you echo SOME_const (or any other capitalization variation) there's no bug either * sometimes it needs one reload and sometimes many (never more than 3 or 4, though) * after you get the bug, comment the first echo and you'll get the right result again; remove the comment and you get the bug again after few reloads * if I print the defined constants I see both constants with the right values (namely 1 and 2) Test script: --------------- define('sOmE_CoNsT', 1, true); echo SOME_CONST; // Prints 1 define('SOME_CONST', 2); echo SOME_CONST; // Prints 2 Expected result: ---------------- Consistently prints "12" on successive page loads Actual result: -------------- Prints "12" the first few times, then "11" on successive page reloads ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=74450&edit=1