[PreRFC] enum-variant-types

[VitWW]

I'm making a future proposal Partial Types v3

And exists topic on Internals - [Pre? RFC] Partial types and partial mutability

And Partial Enums looks like this:

fn f(x: SomeEnum.{Foo}) { ... }

let x: SomeEnum.{Foo} = SomeEnum::Foo(3);