Changed the name of the corresponding package

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

The first character of the regex determines the delimiter; any extra instances of that delimiter need to be escaped.

var_dump( preg_match( '/\Q\/\E/', '/' ) );

The proposed solution is not correct

var_dump( preg_match( '/\Q\/\E/', '/' ) );

Expected result:
----------------
int(1)

Actual result:
--------------
int(0)

My apologies, I see that \Q and \E change the meaning of the escape there.

However, they *don't* change the handling of the delimiter, as that happens before the regex is even passed to PCRE.

In other words, PCRE receives the regex \Q/\E and the modifiers \E/ hence the error message.

HI vklimin,

While suprising, and possibly could be documented better, it appears that \Q and \E probably won't work for what you're trying to use them for: https://stackoverflow.com/a/20520551/778719

"Use preg_quote() instead of \Q \E if the delimiter may appear within \Q \E"

The key here is the term "metacharacters", which are the characters listed here: https://www.php.net/manual/en/regexp.reference.meta.php

I've proposed an edit to the manual to explicitly mention delimiters: https://github.com/php/doc-en/pull/611/files