C module dependencies fail to resolve in Xcode 16.x - "No such module" errors

[ajram23]

When building a project that depends on Hummingbird in Xcode 16.x, the build fails with "No such module" errors for transitive C module dependencies. This affects all C modules in the dependency chain:

_AtomicsShims (from swift-atomics)
CNIOAtomics (from swift-nio)
CNIOBoringSSL (from swift-nio-ssl)

Am I missing something rudimentary?

Environment:

• Xcode 16.3 and 16.4 RC
• macOS with Apple Silicon
• Swift Package Manager
• Building in Release configuration with whole module optimization

Reproduction:

• Create new Xcode project
• Add Hummingbird as SPM dependency
• Import Hummingbird in Swift file
• Build in Release configuration
• Observe "No such module" errors for C modules

Workaround attempts that failed:

• Clean build folder/DerivedData
• Reset package caches
• Update command line tools

[adam-fowler]

I create both a new macOS and iOS swiftUI apps and included Hummingbird in them without any issues. That was using Xcode 16.3
What kind of project are you creating?

[ajram23]

@adam-fowler thanks for getting back right away. Creating a helper app inside a Mac app so on a different target.

[adam-fowler]

@adam-fowler thanks for getting back right away. Creating a helper app inside a Mac app so on a different target.

Ok don't know much about them. I'll have to look into that. Can you verify that a command line app, or swift ui app works fine with your setup.

[Joannis]

@ajram23 you need to check how you've added your Swift dependencies. This tends to happen when you use a library that is't added correctly in your Xcodeproj