Using Library Evolution in a versioned package

Using Swift
1

I had an issue a while back with an XCFramework depending on a Swift Package, where the solution was to enable Library Evolution in the dependency.

The target looks like this:

        .target(
            ...
            swiftSettings: [
                // Emulate BUILD_LIBRARY_FOR_DISTRIBUTION to prevent culling of ABI used by
                // compiled frameworks.
                .unsafeFlags([
                    "-enable-library-evolution",
                    "-emit-module-interface"
                ]),
            ]),

The following works when using the package as a dependency:

    dependencies: [
        .package(url: "...", branch: "main"),
    ],

The following fails:

    dependencies: [
        .package(url: "...", from: "0.0.2"),
    ],

    dependencies: [
        .package(url: "...", exact: "0.0.2"),
    ],

Both produce the following error:

xcodebuild: error: Could not resolve package dependencies:
the target 'PackageName' in product 'PackageName' contains unsafe build flags

Am I doing this right? Is there a different way to trigger full ABI generation in a package or one that doesn't use unsafe flags?

I'm pretty sure I can repackage the XCFramework without specifying a dependency, but that seems worse since errors won't be detected until the app runs and fails to resolve symbols.

2

Unsafe flags are not supported in stable library dependencies (that is, those that use version numbers). I believe this is intentional behaviour.