[Pitch] Lifting restriction on explicit specialization in function calls

Evolution Pitches
4

I agree that this needs improvement, but I think other languages handle it poorly, and the right solution for Swift is to just get rid of the .self. That way, you can use labels, and not have to fill in type placeholders.

E.g. given…

func f<T, U>(
  goodLabel: T.Type = Int.self,
  thingThatIsBestInBetween: some Any,
  evenBetterLabel: U.Type = U.self
) -> (T.Type, U.Type) {
  (T.self, U.self)
}

…

_ = f<_, Void>(thingThatIsBestInBetween: "thing")

is better than

_ = f(thingThatIsBestInBetween: "thing") as (_, Void.Type)

but

_ = f<_, Never>(thingThatIsBestInBetween: "thing")

is worse than

_ = f(thingThatIsBestInBetween: "thing", evenBetterLabel: Never)