Xcode requiring @escaping for closure passed to update

[JimRoepcke]

Writing a function that uses update, and the compiler complains that I have to annotate my closure as @escaping to use it with update, but update doesn't declare the parameter as @escaping. Any idea why this is or how to work around this? I can definitely make my updateClient parameter @escaping, but it seems like this should be unnecessary.

    @MainActor open func testStore(
        initialState: Component.State = .mock,
        updateClient: (inout Component.Client) -> Void
    ) -> TestStoreOf<Component> where Component.State: Equatable & HasMock, Component.Client: HasMock {
        Component.testStore(
            initialState: initialState,
            client: update(.mock, updateClient) // Passing non-escaping parameter 'updateClient' to function expecting an @escaping closure
        )
    }

[stephencelis]

@JimRoepcke I believe the error you're seeing applies to your updateClient closure and not Overture's update. It's hard to get a full picture without knowing what Component.testStore is, but it sounds like it has some escaping requirements that you may need to propagate to updateClient.

Because this doesn't appear to be a bug in the library, I'm going to convert this to a discussion, where hopefully we can get to the bottom of it.

[JimRoepcke]

I have no concern with sharing a bit more code, this is all convenience code, nothing proprietary.

public protocol HasMock {
    #if DEBUG
    static var mock: Self { get }
    #endif
}

public protocol TCAComponent<State, Action, Client>: ReducerProtocol {
    associatedtype State
    associatedtype Action
    associatedtype Client

    init(client: Client)
}

#if DEBUG
public extension TCAComponent where State: Equatable, State: HasMock, Client: HasMock {
    static func testStore(
        initialState: State = .mock,
        client: Client = .mock,
        prepareDependencies: (inout DependencyValues) -> Void = { _ in }
    ) -> TestStore<State, Action, State, Action, Void> {
        TestStore(
            initialState: initialState,
            reducer: Self(client: client),
            prepareDependencies: prepareDependencies
        )
    }
}
#endif

open class TCAComponentTestCase<Component: TCAComponent>: XCTestCase
where Component.State: Equatable & HasMock, Component.Client: HasMock {

    public typealias TestStoreOf<C: TCAComponent> = ComposableArchitecture.TestStore<
        C.State, C.Action, C.State, C.Action, Void
    >

    open func prepare(dependencies: inout DependencyValues) {

    }

    @MainActor open func testStore(
        initialState: Component.State = .mock,
        client: Component.Client = .mock
    ) -> TestStoreOf<Component> where Component.State: Equatable & HasMock, Component.Client: HasMock {
        Component.testStore(initialState: initialState, client: client, prepareDependencies: prepare(dependencies:))
    }

    @MainActor open func testStore(
        initialState: Component.State = .mock,
        updateClient: @escaping (inout Component.Client) -> Void
    ) -> TestStoreOf<Component> where Component.State: Equatable & HasMock, Component.Client: HasMock {
        Component.testStore(
            initialState: initialState,
            client: update(.mock, updateClient),
            prepareDependencies: prepare(dependencies:)
        )
    }
}

updateClient is passed into Overture's update to customize the client for the test store. If I remove @escaping, the build fails because it says I have to provide an escaping closure to update.