Re: [RFC] [Discussion] PREG_THROW_ON_ERROR

On Tue, Jul 28, 2026 at 3:56 AM Osama Aldemeery <aldemeery@gmail.com> wrote: > > Hi all, > > Following the earlier pre-RFC discussion (https://news-web.php.net/php.internals/131783), > I've written this up as a proper RFC: > https://wiki.php.net/rfc/preg_throw_on_error > > Short version: > > a PREG_THROW_ON_ERROR flag you pass to any �c^No���]N� > ���apreg_*() call, so a PCRE error throws a > \PregException you can catch > instead of a warning plus a false / > null you have to notice and then chase through > preg_last_error(). > Same thing JSON_THROW_ON_ERROR and > FILTER_THROW_ON_FAILURE already do for their functions. > It's opt-in, so nothing changes without the flag. > > The flag only changes how an error is delivered. A call does exactly the same thing with it or > without it, byte for byte. > The only difference is that at the end, any error the call would have recorded is additionally > thrown, carrying the same code and > message > preg_last_error()/preg_last_error_msg() > would report. > > For array arguments that means the flag mirrors > preg_last_error()...it throws whatever error the same call leaves > there, > which for preg_replace() over an array is the last-processed > entry, not the first. (In the pre-RFC I'd floated throwing on the first failing element > instead). > Whether the preg_*() functions should stop at the first failing > entry is a separate question about those functions, one that applies with or without the flag, so > it's out of scope here. > > The exception name is settled from the pre-RFC as � > �&y� �Ѹ�!�\PregException (thanks Tim) and the flag as > PREG_THROW_ON_ERROR. > > Target is the next feature release after 8.6 since 8.6's beta1 is too close for this to > conclude discussion and a vote in time. > > I also saw Larry's note asking to hold new business that isn't targeting 8.6 until > the freeze rush is over. > This won't catch 8.6, so I'm not asking for any priority while the freeze is on. But > the pre-RFC discussion was already open before > Larry's note, so I'd rather keep it ticking over quietly than restart it in > September. > If someone prefers I park it until then, please say so and I will. > > Implementation and tests: > https://github.com/php/php-src/pull/22797 > > Thanks, > Osama Hi all, Picking this back up...Quick recap first, since it's been quiet for a couple of weeks. PREG_THROW_ON_ERROR is an opt-in flag you pass to any preg_*() call. With it, a PCRE error throws a \PregException you can catch, instead of the current warning plus a false or null you have to notice and then chase through preg_last_error(). Same thing JSON_THROW_ON_ERROR and FILTER_THROW_ON_FAILURE already do for their functions. Where things landed: - Nothing changes without the flag, byte for byte. All it changes is how an error is delivered. At the end of a call, any error it would have recorded is thrown as well, carrying the same code and message preg_last_error()/preg_last_error_msg() would report. - The exception is \PregException and the flag is PREG_THROW_ON_ERROR, both settled back in the pre-RFC (thanks Tim). - For array arguments the flag mirrors preg_last_error(). It throws whatever error the call leaves there, which for preg_replace() over an array is the last-processed entry, not the first. Whether the functions should stop at the first failing entry is a separate question about those functions, so it's out of scope here. The two points raised during discussion, the exception hierarchy and the warning behavior, are addressed in the RFC as it stands. RFC: https://wiki.php.net/rfc/preg_throw_on_error PR: https://github.com/php/php-src/pull/22797 So consider this my intent to vote... Unless something new comes up, I'll open the vote in about two days. If there's anything you'd want settled first, please bring it up now. Thanks, Osama