Complier can't introduce a list of completions for `Effect<Action>` when using `BindingReducer()` in body

[ValseLee]

Description

• I tried to find any other existing issues or discussion with keyword 'completion' but there is no single one. So I make this issue with a bug Label.
• If I use BindingReducer() in body, compiler stops introducing a list of method completions in Effect<Action>.
• I attached some code blocks and screen captures below.

Checklist

• [ ] I have determined whether this bug is also reproducible in a vanilla SwiftUI project.
• [X] If possible, I've reproduced the issue using the main branch of this package.
• [X] This issue hasn't been addressed in an existing GitHub issue or discussion.

Expected behavior

• Compiler can introduce list of method completions of Effect<Action>.
• Compiler can introduce list of method completions of Reduce<State, Action>.

Actual behavior

• Compiler can't introduce list of method completions of Effect<Action>.
• Compiler can introduce list of method completions of Reduce<State, Action>.

Steps to reproduce

1. When using BindingReducer()

   struct ForIssue: Reducer {
   struct State: Equatable { var id: UUID }
   enum Action: Equatable, BindableAction {
   case binding(BindingAction<State>)
   case onButtonTapped
   }
   
   var body: some ReducerOf<Self> {
   /// if BindingReducer() exists in `body`,
   /// compiler can't introduce list of completions
   BindingReducer()
   
   Reduce { state, action in
     switch action {
     case .binding:
       return .none
   
     case .onButtonTapped:
       return .none
     }
   }
   }
   }

   

2. When stop using BindingReducer()

   struct ForIssue: Reducer {
   struct State: Equatable { var id: UUID }
   enum Action: Equatable, BindableAction {
   case binding(BindingAction<State>)
   case onButtonTapped
   }
   
   var body: some ReducerOf<Self> {
   /// if BindingReducer() exists in `body`,
   /// compiler can't introduce list of completions
   /// BindingReducer()
   
   Reduce { state, action in
     switch action {
     case .binding:
       return .none
   
     case .onButtonTapped:
       return .none
     }
   }
   }
   }

   

3. Reduce<State, Action> method completions are working as normal, if body has BidningReducer() or not.

The Composable Architecture version information

beta 1.0.0

Destination operating system

iOS 16.2

Xcode version information

14.2 (14C18)

Swift Compiler version information

swift-driver version: 1.62.15 Apple Swift version 5.7.2 (swiftlang-5.7.2.135.5 clang-1400.0.29.51)
Target: arm64-apple-macosx13.0

[nivanchikov]

@ValseLee can you try this tip by specifying the generics of your Reduce reducer: Reduce<State, Action> { state, action in … } as per this comment by @tgrapperon: https://github.com/pointfreeco/swift-composable-architecture/discussions/1666#discussioncomment-4212335

public var body: some ReducerOf<Self> {
  BindingReducer()

  Reduce<State, Action> { state, action in
    switch action {
      ... 
    }
  }
}

It generally helped me in similar situations.

[ValseLee]

@nivanchikov So.... I didn't try your solution before, but it is perfectly working! Thank you for your kind explanation with #1666 !

[stephencelis]

@ValseLee This was fixed in a later Xcode, as well. If you can upgrade from 14.2, which was released last year, to 14.3.1, this should be fixed without the need of those generics!

[JeongAYoo]

@stephencelis I'm working on Xcode 15.0.1 with TCA 1.9.2 (destination target is iOS 16) but I have the exact same problem described above... Is there something to check in project's build settings?

(Reduce<State, Action> { state, action in … } this works for me though)