External macro implementation type could not be found

[MiguelG97]

Description

Can someone guide me on how to set up my project to not have the following issues when implementing TCA?
Github repo:

External macro implementation type 'ComposableArchitectureMacros.ReducerMacro' could not be found for macro 'Reducer()

External macro implementation type 'ComposableArchitectureMacros.ObservableStateMacro' could not be found for macro 'ObservableState()'

External macro implementation type 'ComposableArchitectureMacros.ReducerMacro' could not be found for macro 'Reducer()'

Checklist

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

Expected behavior

xcode to not throw errors

Actual behavior

xcode is throwing errors

Reproducing project

Github repo:

All I did is installed the TCA package through SPM.
Once finished I added the library to my target project.
Then, when trying to implement the code a bunch of messages show up:

import ComposableArchitecture

@Reducer
struct LayoutSlice {
    
    @ObservableState
    struct State{
        var isLandScape = false
    }
    
    enum Action{
        case setLandScape
    }
    
    var body: some ReducerOf<Self>{
        Reduce{ state, action in
            switch action{
            case .setLandScape:
                state.isLandScape = true
                return .none
            }
        }
        
    }
}

The Composable Architecture version information

1.15.0

Destination operating system

IOS 17.5

Xcode version information

No response

Swift Compiler version information

No response

[mbrandonw]

Hi @MiguelG97, this project builds just fine for me without any errors. There is a chance you have not enabled macros for your project. In the build errors for your project you may see a number of errors like this:

If you enable all of those it should work fine.

Since this isn't an issue with the library I am going to convert it to a discussion. Please feel free to continue the conversation over there!

[MiguelG97]

That's strange, I remind enabling all macros.
I appreciate your response anyways

[JeromeTonnelierOgury]

Hi!
For some reasons, I've got the same behavior, but the weirdest thing is that the project compiles and works.
I tried to remove TCA and add it again (so that I can enable macros when Xcode asks me to), but the errors keep coming back. Basically, after doing that, if I don't touch anything, I have no error. But as soon as I add event just a line break in a reducer, all errors comes back :-/
I tried to remove all cache/derived data and start again, same result.
What's rellay annoying is that when there is an actual error, I just can't find it. One example os error would be ...MobileMenuView/MobileMenuFeature.swift:24:8 External macro implementation type 'ComposableArchitectureMacros.ReducerMacro' could not be found for macro 'Reducer()'; No such file or directory
Any idea ? It's a pretty big project with Cocoapods, SMP (both local and github hosted).
Thanks 🙏

[holzerryan]

Here's a reference to my closed issue.
#3401 (comment)

[JeromeTonnelierOgury]

Thanks a lot, I'll have a look at it :-)

[usiddiqui-google]

For us, the issue turned out to using Swift 6 in the swift-syntax package while our project was still on Swift 5. So updating it from package(url: "https://github.com/swiftlang/swift-syntax.git", exact: "600.0.1") to .package(url: "https://github.com/swiftlang/swift-syntax.git", exact: "510.0.2"), followed by deleting derived data and rebuilding packages fixed the issue.

[usiddiqui-google]

@mbrandonw lmk if its worth adding it here? I will do a PR.
https://pointfreeco.github.io/swift-composable-architecture/main/documentation/composablearchitecture/reducer/#Error-External-macro-implementation--could-not-be-found

[mbrandonw]

Hi @usiddiqui-google, that seems very surprising. I believe this is an Xcode bug and that the version of Swift Syntax can't really have any impact on this. I would be happy to update the docs, but first I would want to see conclusive evidence that it does indeed fix the problem.