DependencyValue keypath does not conform to sendable

[BrentMifsud]

In the process of swapping out cleanse for swift-dependencies (now that cleanse is archived).

I've been running into this sensibility warning quite a bit while using swift-dependencies.

Has anyone else run into this? Any workarounds?

[mbrandonw]

Hi @BrentMifsud, this is just a bug in Swift <6 and will be fixed once Xcode 16 is officially released. For now you can ignore the warning.

[BrentMifsud]

Hi @BrentMifsud, this is just a bug in Swift <6 and will be fixed once Xcode 16 is officially released. For now you can ignore the warning.

Good to know no action required on my end.

Thanks again for putting this library together. So far, it's been dead simple to work with. Love how it's almost identical to the SwiftUI environment.

Random side question:

Any plans to roll out your own @Entry macro equivalent? For DependencyValues?

[mbrandonw]

Any plans to roll out your own @Entry macro equivalent? For DependencyValues?

There is a PR for part of this (#257) but we're honestly not sure it carries its weight. You can read the discussion here, and please do chime in if you have some ideas to share.

[BrentMifsud]

Seems like this warning still exists in Xcode 16.

[stephencelis]

@BrentMifsud You must either be in Swift 6 language mode (which is still not the default and you must opt into it), or you must enable the InferSendableFromCaptures upcoming feature from your project's build settings or package's Swift settings.

[gsabran]

I've enabled InferSendableFromCaptures in my Swift Package and still get the issue while using Swift 5.

[gsabran]

Compiling with Swift 6 also gives the warning / error

[mnddm]

Hello!
I'm trying to follow the Meet the Composable Architecture tutorials and faced with a similar issue. When I added @Dependency(\.continuousClock) var clock and tried to use it as a timer, I got the error:

Capture of 'self' with non-sendable type 'CounterFeature' in a @Sendable closure

I have Xcode 16 with Swift 6 enabled for my project. I also have a local Swift Package (similar to isowords project structure) where I try to place all my code and the Package also has Swift 6.0 enabled. Enabling the InferSendableFromCaptures option (in Build Settings or in Package settings) doesn't help, moreover it even raises another error that I'm already using Swift 6.0 with this feature.

I believe conforming the CounterFeature to Sendable protocol is wrong way. Am I missing something, could you please help?

Thank you.

[BrentMifsud]

Hello!

I'm trying to follow the Meet the Composable Architecture tutorials and faced with a similar issue. When I added @Dependency(\.continuousClock) var clock and tried to use it as a timer, I got the error:

Capture of 'self' with non-sendable type 'CounterFeature' in a @Sendable closure

I have Xcode 16 with Swift 6 enabled for my project. I also have a local Swift Package (similar to isowords project structure) where I try to place all my code and the Package also has Swift 6.0 enabled. Enabling the InferSendableFromCaptures option (in Build Settings or in Package settings) doesn't help, moreover it even raises another error that I'm already using Swift 6.0 with this feature.

I believe conforming the CounterFeature to Sendable protocol is wrong way. Am I missing something, could you please help?

Thank you.

I think maybe the swift 6 language mode might have some issues.

I tried turning it on, and despite all the concurrency warnings I still have, I was able to build and compile without any issues.

[stephencelis]

Conforming CounterFeature to Sendable is just fine! It will actually infer it for you for types that aren't exported publicly from the module. So if you remove public from this feature, it should build without the explicit conformance, but also explicitly adding the conformance is exactly what you should do when the type is public.

[BrentMifsud]

Seems with Xcode 26 this is still a problem. The new default actor isolation feature seems to not play nicely with this.

[kesprit]

Seems with Xcode 26 this is still a problem. The new default actor isolation feature seems to not play nicely with this.

I have the same issue, I just followed the Composable Architecture Tutorial, I share you my code:

CounterFeature.swift

import ComposableArchitecture
import Foundation

@Reducer
struct CounterFeature {
    @ObservableState
    struct State: Equatable {
        var count = 0
        var fact: String?
        var isLoading = false
        var isTimerRunning = false
    }
    
    enum Action {
        case decrementButtonTapped
        case incrementButtonTapped
        case factButtonTapped
        case factResponse(String)
        case toggleTimerButtonTapped
        case timerTick
    }
    
    @Dependency(\.continuousClock) var clock
    @Dependency(\.numberFact) var numberFact
    
    var body: some Reducer<State, Action> {
        Reduce { state, action in
            switch action {
            case .decrementButtonTapped:
                state.count -= 1
                state.fact = nil
                return .none
            case .incrementButtonTapped:
                state.count += 1
                state.fact = nil
                return .none
            case .factButtonTapped:
                state.fact = nil
                state.isLoading = true
                return .run { [count = state.count] send in
                    try await send(.factResponse(self.numberFact.fetch(count)))
                }
            case let .factResponse(fact):
                state.fact = fact
                state.isLoading = false
                return .none
            case .toggleTimerButtonTapped:
                state.isTimerRunning.toggle()
                if state.isTimerRunning {
                    return .run { send in
                        for await _ in await self.clock.timer(interval: .seconds(1)) {
                            await send(.timerTick)
                        }
                    }
                    .cancellable(id: CancelID.timer)
                } else {
                    return .cancel(id: CancelID.timer)
                }
            case .timerTick:
                state.count += 1
                state.fact = nil
                return .none
            }
        }
    }
}

public enum CancelID: String {
    case timer
}

NumberFactClient.swift

import ComposableArchitecture
import Foundation

struct NumberFactClient {
  var fetch: @Sendable (Int) async throws -> String
}

extension NumberFactClient: DependencyKey {
  static let liveValue = Self(
    fetch: { number in
      let (data, _) = try await URLSession.shared
        .data(from: URL(string: "http://numbersapi.com/\(number)")!)
      return String(decoding: data, as: UTF8.self)
    }
  )
}

extension DependencyValues {
  var numberFact: NumberFactClient {
    get { self[NumberFactClient.self] }
    set { self[NumberFactClient.self] = newValue }
  }
}

Can you help me?

[mbrandonw]

@kesprit as mentioned above, please provide a full project, not just code snippets. Xcode 26 / Swift 6.2 now comes with entirely different compilation modes and so these errors can largely depend on how your project is set up.

[kesprit]

TCAtuto.zip
@mbrandonw here's my project, sorry

[mbrandonw]

Thanks for that. The problem is that your project is using default main actor isolation, which is unfortunately the default in new Xcode 26 projects. I personally don't really recommend using that setting as I find it largely gets in your way rather than simplifying things. And you are probably going to have a problem with every 3rd party library with that setting, and even many of Apple's own frameworks don't play nicely with that setting.

But, if you really do want to use that setting, you will find that you often need to mark things as nonisolated. For example, the error you are getting right now is because the DependencyValues.numberFact property you created is main actor isolated and main actor key paths are never Sendable.

So, the fix is to make it non-isolated:

extension DependencyValues {
  nonisolated var numberFact: NumberFactClient {
    …
  }
}

[kesprit]

Thanks a lot for the explenation @mbrandonw it's very clear, I'll follow your advice and change the settings.
Both solutions work for me.
For people who will read this, the setting to change is "Default Actor Isolation" -> nonisolated