Am I hitting a compiler bug?

[Jens]

@Slava_Pestov

We have tests that cover this case and it's supposed to work. It's a short-hand for "forwarding" all the arguments verbatim.

I agree it's kind of a funny feature but people do rely on it and we can't take it out now; we need to fix any bugs that it causes instead.

So I guess this short-hand form should be documented in this section: The Swift Programming Language: Redirect

(Not sure if request for doc improvements should be reported like this but, here you go: SR-7931.)

And more generally, a lot of the behavior of type aliases, associated types and extensions is both undocumented and inconsistent/broken.

Properly documenting the intended behavior would certainly help not only us (new and seasoned) users but also the compiler devs.