Swiftc arguments in Swift Package

Question

I hava a Swift Package with an executable target, the project structure looks like this:

MySwiftPackage
├── Package.swift
├── Sources
│   └── MySwiftPackage
│       ├── SwiftBridgeCore.swift
│       ├── main.swift
│       └── my_rust_lib.swift
├── bridging-header.h
├── file.json
├── generated
│   ├── SwiftBridgeCore.h
│   └── my_rust_lib
│       └── my_rust_lib.h
└── lib_mac
    └── libmy_rust_lib.a

This package needs to link to the static library lib_mac/libmy_rust_lib.a and links with the bridging-header.h.

The bridging-header.h just has some #include to the headers in generated.

To build this project, I run

swiftc -L lib_mac -lmy_rust_lib \
    -import-objc-header bridging-header.h \
    Sources/LinuxSwiftPackage/*.swift

This will build an executable I can run. I now want to accomplish the same this using swift build, so that I can add dependencies.

I have tried the following:

1. In my Package.swift, I added the following:

let package = Package(
    name: "MySwiftPackage",
    dependencies: [],
    targets: [
        .executableTarget(
            name: "MySwiftPackage",
            dependencies: [],
            cSettings: [ 
                .headerSearchPath(".")
            ],
            linkerSettings: [
                .linkedLibrary(":lib_mac/libmy_rust_lib.a")
            ]
        )
    ]
)

This did not link the library however, as I got a lot of cannot find type <SomeType defined in the header> in scope

2. I have added the following to Package.swift:

let package = Package(
    name: "MySwiftPackage",
    dependencies: [],
    targets: [
        .executableTarget(
            name: "MySwiftPackage",
            dependencies: [],
            linkerSettings: [
                .unsafeFlags(["-L lib_mac", "-lmy_rust_lib", "-import-objc-header bridging-header.h"])
            ]
        )
    ]
)

This would yield the same errors.

I also tried swiftSettings instead of linkerSettings, this would give me the following error: ld: symbol(s) not found for architecture x86_64

3. I have tried the following:

file.json

{
    "version": 1,
    "sdk": "/Library/Developer/Toolchains/swift-latest.xctoolchain/usr/bin/swift",
    "toolchain-bin-dir": "/Library/Developer/Toolchains/swift-latest.xctoolchain/usr/bin",
    "target": "x86_64-apple-macosx",
    "dynamic-library-extension": "lib",
    "extra-cc-flags": [
    ],
    "extra-swiftc-flags": [
        "-L",
        "lib_mac",
        "-lmy_rust_lib",
        "-import-objc-header",
        "bridging-header.h"
    ],
    "extra-cpp-flags": []
}

with a Package.swift that looks like this:

let package = Package(
    name: "MySwiftPackage",
    dependencies: [],
    targets: [
        .executableTarget(
            name: "MySwiftPackage",
            dependencies: []
        )
    ]
)

I then ran swift build --destination file.json, with would give me the following error:

error: no such module 'Foundation'
import Foundation

---

Will any of these approaches work with some changes? Or is there another approach that should work?

Thanks in advance,
Jonas

P.S. I'm using macOS (12)