Protocol existential crisis

Protocol.Type.swift

protocol P {}
struct A: P {}
struct B: P {}
struct C: P {}

var someP: P.Type = A.self
someP == A.self // true
someP == B.self // false

switch someP {
case A.self: print("It's an A") // Expression pattern of type 'A.Type' cannot match values of type 'P.Type'
default: print("It's some other P")
}

func ~=(rhs: P.Type, lhs: P.Type) -> Bool {
    return rhs == lhs
}

switch someP {
case A.self: print("It's an A") // "It's an A"
default: print("It's some other P")
}