value of type '_ -> _' has no member 'init'

Break.swift

class X : NSCoding {
    @objc func encodeWithCoder(aCoder: NSCoder) {fatalError()}
    @objc required init?(coder aDecoder: NSCoder) {fatalError()}
}
class B {}
class A<T>:X {}
class C:A<B> {
    init(x:Int) {super.init()}
}

//
// If there is a class adopting NSCoding somewhere in the superclass chain, we get:
//
// 8:24: error: value of type '_ -> _' has no member 'init'
//    init(x:Int) {super.init()}
//                 ~~~~~~^~~~