Build failures seems unrelated.

I'd like to hear @muglug's opinion whether it makes sense to allow and read @template-covariant above functions and methods.

My opinion is that it's not entirely wrong to use that, in a world where you're able to materialize function foo<T of Foo> as a type - invariant version would only accept foo<Foo>, covariant version would also accept foo<Bar> where Bar extends Foo.

Yes, I will have to give it a thought. I wanted to disable it here as there is no point having declaration site variance for functions but it is actually use-site variance with the same syntax :D

@template-covariant doesn't really make sense to me for methods – does it exist in other languages?

Ok, seems its not supported anywhere, I researched some langs and added this info explicitly into table: https://hrach.dev/posts/variance-elsewhere/

Please fix the build and I'll merge it (PHP 8 tests are now expected to fail.)

It's enough to run GenericsIntegrationTest locally and commit the updated JSON files.

Done, thanks!

Thank you!