swift 6.4

Swift 6.4 is a Windows-relevant release of Apple's Swift programming language, and this tag follows how it changes the developer experience on Microsoft's platform. The headline shift is that running swift build, swift test, or swift run for a Swift package on Windows now uses Swift Build instead of Swift Package Manager's older native build engine, aligning the build path with Linux and macOS. Existing SwiftPM projects are expected to keep working through the same familiar commands, with the toolchain routing them to the new engine behind the scenes. Coverage here focuses on what that means for Windows developers building and testing Swift packages.