Bypass a Swift compiler bug in generic subclass associated object

[devxoul]

I found something weird. Reactor's action is created again after the state stream is created when subclassing a generic class.

// Generic class
class ParentReactor<T>: Reactor {
  enum Action {}
  typealias Mutation = Void
  typealias State = Void
  let initialState: State = State()
}

// Subclass
class ChildReactor: ParentReactor<String> {
}

let reactor = ChildReactor()
let address1 = ObjectIdentifier(reactor.action).hashValue // 140212178080688
_ = reactor.state // will call createStateSteam()
let address2 = ObjectIdentifier(reactor.action).hashValue // 140212178094112
XCTAssertEqual(address1, address2) // FAIL