Re: [RFC] Disallow multiple default blocks in a single switch statement

On Wed, Aug 6, 2014 at 12:16 PM, Rowan Collins <rowan.collins@gmail.com> wrote: > Ferenc Kovacs wrote (on 06/08/2014): > >> Hi, >> >> I think dropping this behavior is a good idea, but I'm confused by the >> reasoning related to the langspec. >> This rfc targets php.next (which is a safe move as this has BC break >> albeit >> would require some questionable code), but the langspec was agreed to be >> based on 5.6 and document how that works. >> So even if we accept this rfc, and remove the multiple default case, >> wouldn't we still need to document the current behavior in the spec (maybe >> mentioning that it will go away in php-net)? > > > According to the bug report, HHVM also accepts multiple default blocks, but > uses the first rather than the last. It's probably not worth implementing > specific code there to take the last default label just in order to adhere > to a 5.6 spec, but is worth making it detect multiple labels to bring it in > line with the proposed change. > > So either we declare the php.net implementation to be in violation of the > spec (which isn't completely insane - the spec shouldn't mirror behaviour to > the point of incorporating the entire bug list); or we document the php.net > behaviour as "correct", but accept that nobody is going to implement that > part of the spec as written, and fix it in the next release of both the > implementation and the spec. > > Having the 5.6 spec match behaviour, and starting a 5.7 draft immediately > for implementations to actually target might be a compromise? Too late for 5.6 but it would have been one of these acceptable BC and sanity change. I did not even know it was possible and I do not think anyone would be insane enough to rely on that :) We will need a 5.7 anyway, so yes, 5.7 sounds like a reasonable target. And I indeed like this RFC, specs work is paying off. Cheers, -- Pierre @pierrejoye | http://www.libgd.org