ProtocolInitializers Fix.swift

import Foundation

class Animal: NSObject {
}

protocol Named {
    init(name: String)
}

protocol AnimalSpecification {
    associatedtype AnimalType: Animal
}

//This workaround doesn't add any extra type information, but fixes the problem 
func workaround<AnimalType>(name: String) -> AnimalType where AnimalType: Named {
    return AnimalType(name: name)
}


extension AnimalSpecification where AnimalType: Named {
    func animal(named name: String) -> AnimalType {
        return workaround(name: name)
    }
}

class Dog: Animal, Named {
    let name: String
    required init(name: String) {
        self.name = name
        super.init()
    }
}

struct Kennel: AnimalSpecification {
    typealias AnimalType = Dog
}

let kennel = Kennel()
kennel.animal(named: "Brian")

ProtocolInitializers.swift

import Foundation

// Removing the subclassing from NSObject fixes the problem
class Animal: NSObject {
}

protocol Named {
    init(name: String)
}

protocol AnimalSpecification {
    associatedtype AnimalType: Animal
}

extension AnimalSpecification where AnimalType: Named {
    func animal(named name: String) -> AnimalType {
        return AnimalType(name: name)
    }
}

class Dog: Animal, Named {
    let name: String
    required init(name: String) {
        self.name = name
        super.init()
    }
}

struct Kennel: AnimalSpecification {
    typealias AnimalType = Dog
}

let kennel = Kennel()
kennel.animal(named: "Brian")

This produces this error:

Removing NSObject as superclass from Animal makes it work as expected