swiftLanguageVersions
property in PackageDescription manifest API for tools version 4.2 is changed from an array of Integers to an array of SwiftVersion enum.swift-4.2-RELEASE
designates the specific revisions in those repositories that make up the final version of Swift 4.2.swift-4.2-branch
will remain open, but under the same release management process, to accumulate changes for a potential future bug-fix “dot” release.