Why does an already constrained protocol still have "self or associated type requirements"?

Using Swift
1

Please see the code below. I don't see how the inheriting protocol is an incomplete type. In the world of C++ this would be a specialization, I guess, making the type non generic.

It would also be great to hear of alternative approaches for what I'm trying to achieve. Thanks!

protocol GenericProtocol {
    associatedtype Collaborator
    func add(_ collaborator: Collaborator)
}

protocol IntProtocol: GenericProtocol where Collaborator == Int {
}

struct IntImpl: IntProtocol {
    func add(_ collaborator: Int) {
    }
}

let specializedRef: IntProtocol = IntImpl() // Protocol 'IntProtocol' can only be used as a generic constraint because it has Self or associated type requirements
2

Please read this thread, which asked the same question.

3

Interesting reads, thanks for the amazingly quick reply. So this feature is somewhat supported by the current model, but waiting for an improvement to the compiler?

4

Yes, mostly.

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