Related: PHP CodeSniffer: T423831: add rule to warn or require 2nd parameter when using PHP's preg_quote() function

What

• mass refactor code that both 1) uses PHP's preg_quote() function (preg_quote(string $str, ?string $delimiter = null): string) without a second parameter and 2) has a delimiter that is not automatically escaped. example: /.
• to check: CodeSearch (26 files)

Why

• prevent bugs. omitting the second parameter of the preg_quote() sometimes causes the regex function to not match anything due to incorrect delimiter escaping, and emits a PHP warning. this is because PCRE reads /Test/String/ as a syntax error. it should instead be /Test\/String/. preg_quote() will escape that middle slash if the 2nd parameter is provided.

<?php

// The bug
$haystack = 'Hi, this contains a Test/String.';
$subpattern = 'Test/String';
$escaped = preg_quote( $subpattern );
$regEx = '/' . $escaped . '/';
// generates PHP warning, then gives no matches
preg_match_all( $regEx, $haystack, $matches );
echo $matches[0][0] ?? '';

// The fix: add '/' as the second parameter of preg_quote()
$haystack = 'Hi, this contains a Test/String.';
$subpattern = 'Test/String';
$escaped = preg_quote( $subpattern, '/' );
$regEx = '/' . $escaped . '/';
preg_match_all( $regEx, $haystack, $matches );
echo $matches[0][0] ?? '';

Warning: preg_match_all(): Unknown modifier 't' in /home/user/scripts/code.php on line 9
Test/String

• PHP sandbox: https://onlinephp.io/c/db985
• List of delimiters that don't need to be refactored because they're automatically escaped (but it wouldn't hurt to add them): . \ + * ? [ ^ ] $ ( ) { } = ! < > | : - #
• Partial list of delimiters that definitely need to be refactored to avoid bugs: /