Bug #77364 [NEW]: preg_quote incorrectly escapes # character

From: peku33 at gmail dot com Operating system: Linux PHP version: 7.3.0 Package: *Regular Expressions Bug Type: Bug Bug description:preg_quote incorrectly escapes # character Description: ------------ preg_quote function escapes # character, while it shouldn't. This breaks IPBoard 4.3.6 forums in which friendly urls uses custom regexes with #, @, ? characters in url templates. Urls are passed through preg_quote function and # is replaced with \#. In next section {#} should be replaced with (\d+), but this fails, since there is {#} but {\#}. PHP 7.3.0-2 (cli) (built: Dec 17 2018 09:51:53) ( NTS ) Copyright (c) 1997-2018 The PHP Group Zend Engine v3.3.0-dev, Copyright (c) 1998-2018 Zend Technologies with Zend OPcache v7.3.0-2, Copyright (c) 1999-2018, by Zend Technologies Test script: --------------- <?php $inputs = ['#', '?', '@']; foreach($inputs as $input) { var_dump($input, preg_quote($input)); } Expected result: ---------------- string(1) "#" string(1) "#" string(1) "?" string(2) "\?" string(1) "@" string(1) "@" Actual result: -------------- string(1) "#" string(2) "\#" string(1) "?" string(2) "\?" string(1) "@" string(1) "@" -- Edit bug report at https://bugs.php.net/bug.php?id=77364&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=77364&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=77364&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=77364&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=77364&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=77364&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=77364&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=77364&r=needscript Try newer version: https://bugs.php.net/fix.php?id=77364&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=77364&r=support Expected behavior: https://bugs.php.net/fix.php?id=77364&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=77364&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=77364&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=77364&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=77364&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=77364&r=dst IIS Stability: https://bugs.php.net/fix.php?id=77364&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=77364&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=77364&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=77364&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=77364&r=mysqlcfg