How to use BindingState through protocol?

[kakhaberikiknadze]

Assuming I've got module A and module B
Module A contains view and a protocol for reducer and Module B contains the implementation of reducer.

Example

Module A

public protocol MyState: Equatable {
  var isOn: BindingState<Bool> { get } // I can't use property wrapper here like @BindingState var isOn: Bool { get }
}

public protocol MyAction: BindableAction {
}

public protocol MyReducer: ReducerProtocol  where State: MyState, Action: MyAction {}

public struct MyView<ViewState: MyState,   Action: MyAction>: View {
  @ObservedObject private var viewStore: ViewStore<ViewState, Action>

  init(store: Store<ViewState, Action> {
    viewStore = .init(store, observe: { $0 }
  }

  public var body: some View {
    Toggle(isOn: viewStore.binding(\.$isOn) { // This method is unavailable. How to unlock this binding method while using protocol?
      Text("Foo")
    }
  }
}

Module B

struct ConcreteReducer: MyReducer {
  struct State: MyState {
    @BindingState var isOn: Bool // Compiler would still complain and ask to add var isOn: BindingState<Bool> instead to conform MyReducer.
  }

  enum Action: MyAction {
    case binding(BindingAction<State>)
  }

  var body: some ReducerProtocol<State, Action> {
    Reduce { state, action in 
      // ..
    }

    BindingReducer()
  }
}

[stephencelis]

Property wrappers' inability to fulfill protocol requirements is a known limitation in Swift. I tried to dig up an issue, but couldn't find one unfortunately. You may have better luck tracking it down than I've had, or you may want to file an issue.

If you really need a protocol here, you can adopt non-property wrapper usage:

 var isOn: BindingState<Bool> { get }
 …
-Toggle(isOn: viewStore.binding(\.$isOn)) {
+Toggle(isOn: viewStore.binding(\.isOn)) {  // no need for `$`

[kakhaberikiknadze]

Yeah currently I'm using non-propery wrapper method but been wondering if it could somehow be achieved. Perhaps future swift version might have some flexibility in that sense 🤞🏻