以前は無条件にmodule.modulemapを生成して、それ経由でリンクしていたはずです。 https://github.com/apple/swift-package-manager/pull/1406

[Xcodeproj] Avoid generating module.modulemap if umbrella header...

This was rewritten #955 for master. This PR increases the portability of generated Xcode project by reducing the use of module.modulemap which absolute path contains. If clang module has umbrella...

12:38 PM

あ、マージされたのはこっちか。 https://github.com/apple/swift-package-manager/pull/1602

[Xcodeproj] Use Xcode's modulemap generation when umbrella header ...

…present This makes the C language frameworks actual frameworks when umbrealla header is present in the target. It should be possible to embed these targets in other Xcode projects using subproject...