Can not load external target settings via SPM

Hi @liaoyuanng! I’m Dosu and I’m helping the tuist team.

This is a known limitation in Tuist: cxxSettings (such as preprocessor macros and conditional compilation flags) defined in external Swift Packages are not automatically propagated to dependent app targets when generating Xcode projects with Tuist. This is by design—Tuist emphasizes explicit configuration and does not merge or forward these settings from SPM packages to your app target automatically. As a result, macros like SHOULD_COMPILE_LOOKIN_SERVER or SPM_LOOKIN_SERVER_ENABLED won’t be available unless you add them yourself docs.

Workaround:
You need to manually add the required compiler flags or macros to your Tuist manifest. You can do this in your Project.swift or Target.swift by specifying them in the settings for your app target. For example:

let project = Project(
  // ...
  targets: [
    Target(
      name: "App",
      // ...
      settings: .settings(
        base: [
          "OTHER_CPLUSPLUSFLAGS": "$(inherited) -DSHOULD_COMPILE_LOOKIN_SERVER -DSPM_LOOKIN_SERVER_ENABLED"
        ]
      ),
      // ...
    )
  ]
)

Alternatively, if you only need to set flags for specific source files, you can use the compilerFlags property in the SourceFileGlob struct docs:

sources: [
  .glob("Sources/App/**", compilerFlags: "-DSHOULD_COMPILE_LOOKIN_SERVER -DSPM_LOOKIN_SERVER_ENABLED")
]

If your SPM dependency uses disableWarning flags, Tuist 4.96.0+ supports mapping those to the appropriate Xcode build settings, but this does not cover general cxxSettings propagation PR #8549.

After making these changes, regenerate your project with tuist generate and verify in Xcode that the flags appear in the build settings for your app target.

For now, manual configuration is required for any macros or flags you expect from SPM cxxSettings. There is ongoing discussion about improving this, so keep an eye on future Tuist releases if this is critical for your workflow discussion.

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@dosu it’s not working

To help troubleshoot, could you clarify what exactly isn’t working? For example, are the macros still missing in your app target, or is there a build error? Could you share the relevant part of your Tuist manifest (like your Project.swift/Target.swift) showing how you added the flags, and confirm if you ran tuist generate and did a clean build? If you have any build logs or screenshots of your Xcode build settings, that would help too.

Just to confirm, Tuist does not automatically propagate cxxSettings from SPM packages—you have to manually add the required flags to your app target’s settings for them to appear in the build. Sometimes, settings at the project level are overridden by target-level settings, so the flags need to be set directly on the target that needs them. If you can share your current setup, I can help spot what might be missing or misconfigured.

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