@swift-5.2.5
protocol SomeProtocol {} extension Int: SomeProtocol {} extension Bool: SomeProtocol {} extension SomeProtocol { func toOpaque() -> some SomeProtocol { return 1 } func toProtocol() -> SomeProtocol { return 1 } } let a = 1.toOpaque() let b = 1.toProtocol() withUnsafeBytes(of: a) { (pointer) in print(pointer.count) } withUnsafeBytes(of: b) { (pointer) in print(pointer.count) }