Linker flag specified in Package.swift as unsafe flag is passed to main app target. steps: create empty package and add linkerSettings: [.unsafeFlags(["-Wl,-make_mergeable"])] to target import PackageDescription let package = Package( name: "TestPackage", products: [ // Products define the executables and libraries a package produces, making them visible to other packages. .library( name: "TestPackage", type: .dynamic, targets: ["TestPackage"]), ], targets: [ // Targets are the basic building blocks of a package, defining a module or a test suite. // Targets can depend on other targets in this package and products from dependencies. .target( name: "TestPackage", linkerSettings: [.unsafeFlags(["-Wl,-make_mergeable"])] ), .testTarget( name: "TestPackageTests", dependencies: ["TestPackage"]), ] ) create empty Xcode iOS app project and add package to project via Add Files 3 add package as a framework dependency to the main app in the result, build fails with error: ld: -make_mergeable can only be used when creating a dynamic library package itself builds with -mergable_library and that is fine