[swift-evolution] [Pitch] "unavailable" members shouldn't need an impl

[Brent Royal-Gordon]

> However, you can (and still need to) provide an implementation (e.g. function body). You can just stick a fatalError() inside and be done with it, but my question is, is an impl even necessary?

Personally, I always figured the best thing to do was to call through to the new API. We don't have library resilience yet, but I'm assuming that's what you'll have to do in resilient code when you want to retire an API, just in case you get loaded by something compiled against an old version.

-- 
Brent Royal-Gordon
Architechies