[PRE-RFC] PREG_THROW_ON_ERROR flag

Hi all, I'd like to propose adding a PREG_THROW_ON_ERROR flag to the preg_*() functions, and gauge interest in that. Json and ext/filter both grew an opt-in way to turn a silent error into an exception...that is JSON_THROW_ON_ERROR and FILTER_THROW_ON_FAILURE. PCRE is the one left out where a failing call is easy to miss. An execution error for example (e.g. a bad UTF-8) surfaces only if you call preg_last_error() afterwards, and a malformed pattern emits a warning and returns false. PREG_THROW_ON_ERROR would do for PCRE what those two do for their functions. Passing it to any preg_*() call makes a PCRE error throw a Pcre\PcreException that carries the PREG_*_ERROR code and the preg_last_error_msg() text instead of warning or returning false/null. And it covers both kinds: a compilation error (e.g. a malformed pattern) and an execution error, so opting in means any PCRE failure becomes a single catchable exception. Also, preg_replace() and preg_filter() gain an optional $flags parameter to accept it (the only two without one as far as I know). Concretely, the check you'd write today: ``` if (preg_match($pattern, $subject, $m) === false) { throw new RuntimeException(preg_last_error_msg()); } ``` ...collapses to: ``` preg_match($pattern, $subject, $m, PREG_THROW_ON_ERROR); ``` First, I'd like to know whether there's interest at all and whether anyone sees a reason not to add it. If there is interest, a couple of design questions I'd want the list's read on: 1. Array subjcets. Currently preg_last_error() reflects only the last element processed, but I'd have the flag throw on the first failing element rather than keep last-one-wins...does that seem right? 2. Whether *_ON_ERROR reads better than *_ON_FAILURE given the existing preg_last_error()/PREG_*_ERROR vocabulary. If it seems worth pursuing, I'll write it up as a proper RFC. Thanks, Osama