RFC: add a Type called AnyType that's subtyped by all other types except Any

I disagree with that position. The fact that you can pass a non-type to a parametric type that explicitly has a <: Any declaration on that type parameter is a bug plain and simple (and not one that has anything to do with grammar or syntax). If there’s code that breaks when that bug gets fixed then so be it—that code has to be fixed. Semantic versioning does not mean we can’t make any changes that change the behavior of any code anywhere. It means we can’t make breaking changes to documented and intentional APIs which I don’t believe this to be.