[RFC] [VOTE] PREG_THROW_ON_ERROR

Hi

The discussion period for PREG_THROW_ON_ERROR has passed with no open
issues, so I'm opening the vote.

Recap: the RFC adds an opt-in PREG_THROW_ON_ERROR flag.
Pass it to any preg_* matching function and any PCRE error the call
records is additionally thrown as a \PregException, so you can catch it
instead of checking the return value.
The exception's code and message match preg_last_error() and
preg_last_error_msg() exactly, and a call without the flag behaves
exactly as it does today.

RFC: https://wiki.php.net/rfc/preg_throw_on_error
PR: https://github.com/php/php-src/pull/22797

Voting is open now and closes on 2026-09-18 17:00:00 UTC.

I regretfully were not able to work through the list backlog after my
summer vacation and thus also missed the intent to vote. I have just
read through the RFC and voted against it, despite being in agreement of
the general concept.

Specifically:

1. I disagree with keeping the Warning on compilation errors. This
   feature is entirely new and opt-in, thus there are no backwards
   compatibility expectations or considerations. The $e->getMessage() === preg_last_error_msg()`` guarantee makes the feature much worse than it
   could be for compilation errors. Including all necessary information in
   the Exception is a must for me.

2. I disagree with the behavior of not wrapping Exceptions thrown in
   user callbacks: I believe the correct choice is to throw a
   \PregException with the Exception thrown in the callback as the
   ->previous exception. Not wrapping the user callback exception means
   that one needs a catch(Exception) with a try just around the preg_
   call to reliably handle all errors during regular expression execution,
   which nullifies much of the benefit of having a dedicated exception
   class in the first place.

It also violates the exception policy in
https://github.com/php/policies/blob/main/coding-standards-and-naming.rst#throwables,
which states:

If an extension uses external functionality that may throw an exception it MUST wrap any exception thrown by that functionality into an appropriate exception of its own. It MUST set the $previous property to the original exception when doing so.

Best regards
Tim Düsterhus