protocol AnimalProtocol { func speak() -> String } protocol CatProtocol : AnimalProtocol { func nya() -> String } class AnimalEater { func accept<X : AnimalProtocol>(_ x: X) {} } class CatEater : AnimalEater { override func accept<X : CatProtocol>(_ x: X) { print(x.nya()) } } class Dog : AnimalProtocol { func speak() -> String { return "bow wow" } } let catEater = CatEater() let animalEater = catEater as AnimalEater let dog = Dog() animalEater.accept(dog) // file:///Users/omochi/work/playground/iOSGround.playground: error: Playground execution aborted: error: Execution was interrupted, reason: EXC_BAD_ACCESS (code=1, address=0x0). // The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation. (edited)
