On Wed, May 8, 2019 at 4:06 AM Nikita Popov <nikita....@gmail.com> wrote:
> On Tue, Jan 22, 2019 at 6:59 PM Levi Morrison <le...@php.net> wrote: > > > On Tue, Jan 15, 2019 at 1:27 PM Christoph M. Becker <cmbecke...@gmx.de> > > wrote: > > > > > > On 04.01.2019 at 20:17, Levi Morrison wrote: > > > > > > > I intend to close the vote in a day or two, unless I hear of new> > > issues from Dmitry or others. > > > Any news here? > > > > > > -- > > > Christoph M. Becker > > > > I sent this a week ago to Christoph only; oops. > > > > I have not heard any news. The vote is now closed. The RFC passes 39 > > in favor to 1 against. > > > > Special thanks to Nikita and Dmitry who have helped find issues and > > review the patch. It will not be merged until the implementation > > quality is satisfactory. > > > > As we're moving steadily towards 7.4 feature freeze, I'd like to discuss > what we want to do with this RFC... The current implementation doesn't work > correctly (I've done some more work in > https://github.com/nikic/php-src/commits/variance-7.4, but it's also > incomplete) and I have some doubts about how we're approaching this in > general. > > This RFC really has two parts: > 1. The actual variance change. This is a very straightforward change and > there are no issues here. > 2. The ability to check variance across multiple consecutive class > definitions. This allows type declarations to reference classes that are > declared later in the same file (but within one "block" of declarations). > > The second part is technically more dicey and somewhat arbitrary when seen > in the wider scope of how class hoisting and early binding work in PHP: > While PHP supports declaring classes "out of order" in some very simple > cases like this... > > class B extends A {} > class A {} > > ...it will not work for anything more involved than that, for example > > class C extends B {} > class B extends A {} > class A {} > > will already generate a "class not found" error. > > Now the variance RFC tackles one very specific part of this long-standing > issue: The types referenced in parameter and return types may be declared > later in the file (even if used variantly), but all other uses of the types > still need to respect the declaration order. > > I think that we should be separating these two issues (variance and > declaration order), and land the simple variance support in 7.4, while > tackling the declaration order problem *in full* separately (in PHP 8, > because I think we may want to make some BC breaking changes, in particular > by making the class hoisting unconditional.) > > Thoughts on this approach? > As I read it, the RFC [1] aims to address the variance problem. The declaration problem is related - but separate. Seems to me, solving the variance problem is the primary concern. Since declarations are therefore a secondary concern, I agree with the separation. (More the so because, IMO, it's better to solve a problem holistically.) [1]: https://wiki.php.net/rfc/covariant-returns-and-contravariant-parameters
