A Swift-based package imported in an ObjC-based package is not visible when ObjC package is itself imported in another Swift package

[glaurent]

Description

Given a Swift package containing Swift code named TestPackage.

This package is a dependency of another Swift package which contains ObjC code, call it TestObjCPackage.

TestObjCPackage builds perfectly fine on its own. In it there's a public header include/Header.h which has the line '@import TestPackage;'.

On top of that I have another Swift package, containing Swift code, which has TestObjCPackage as a dependency, call it TestLvl2Package.

Problem : when building TestLvl2Package, I get an error "Module 'TestPackage' not found" on TestObjCPackage/include/Header.h.

The only way around this is to add an unsafe flag in TestLvl2Package to specify the modulemap of TestPackage :

.target( name: "TestLvl2Package", dependencies: [.product(name: "TestObjCPackage", package: "TestObjCPackage")], swiftSettings: [.unsafeFlags(["-Xcc", "-fmodule-map-file=$GENERATED_MODULEMAP_DIR/TestPackage.modulemap"])] )
I'm adding a zip file with the packages for easy reproduction.
TestPackages.zip

Reproduction

Expected behavior

No build error and no need to add an unsafe flag.

Environment

swift-driver version: 1.90.11.1 Apple Swift version 5.10 (swiftlang-5.10.0.13 clang-1500.3.9.4)

Additional information

No response