On Thu, Jan 9, 2020 at 10:15 AM Nikita Popov <nikita....@gmail.com> wrote:
> Hi internals, > > I've prepared https://github.com/php/php-src/pull/5068 to fix validation > of > abstract methods inside traits for PHP 8. > > To provide some context, the situation is currently pretty weird... when > you add an abstract method in a trait, you obviously do that because the > trait requires that method to exist with the given signature. However, this > is currently enforced only spottily: > > * It is not enforced in the most common case, where the method > implementation is provided by the using class: https://3v4l.org/SeVK3 > * It is enforced if the implementation comes from a parent class: > https://3v4l.org/4VCIp > * It is enforced if the implementation comes from a child class: > https://3v4l.org/q7Bq2 > > I believe that an abstract methods signature coming from a trait should > always be enforced. > > Conversely, we currently have some very weird code lying around that > instead does a bi-directional signature enforcement if there are two traits > specifying the same abstract method: https://3v4l.org/8Ze2C > > I believe this case should be valid instead, as the implementation of the > method provided by the class satisfies both signatures. > > Does anyone see an issue with making these validation changes for PHP 8? I > can also make an RFC for this, but it seems more like an implementation bug > to me (especially seeing how there's about zero test coverage for any of > this). > +1, for improving logical coherence around traits and for simplifying the engine code. Since @nicolas-grekas demonstrated a legitimate BC break, I think we do need an RFC. That would also give some time to discuss merits of private abstract declarations in traits.
