I'm trying to set up a Swift Package that target's macOS Big Sur. From the documentation, it looks like v11 should be the new property. https://developer.apple.com/documentation/swift_packages/supportedplatform/macosversion/3632902-v11 platforms: [.macOS(.v11)], But it crashes with the following error. error: manifest parse error(s): Package.swift:9:17: error: reference to member 'v11' cannot be resolved without a contextual type tttt.macOS(.v11) Oddly, an undocumented v10_16 works! platforms: [.macOS(.v10_16)], Looking at the open source code, it appears both values should work. https://github.com/apple/swift-package-manager/blob/6cfe2de63e53dd9cb75e7bf910277e699d9383a2/Sources/PackageDescription/SupportedPlatforms.swift#L212-L223 Is there a bug in this release of Xcode's Swift tool chain? What platform property should I be using to target Big Sur? Xcode Version 12.0 beta (12A6159) $ swift --version Apple Swift version 5.3 (swiftlang-1200.0.16.9 clang-1200.0.22.5) Target: