Swift 5.9 Released

This is a major new release that adds an expressive macro system to the language and introduces support for integrating Swift into C++ codebases through bidirectional interoperability.

→ swift.org/blog/swift-5.9-released/

Swift 5.9 introduces a powerful macro system for expressive libraries, parameter packs for flexible generic APIs, and ownership features like consume and noncopyable types to optimise low-level code performance.

It enhances debugging with faster expression evaluation, better crash handling with backtraces on Linux and macOS, and bidirectional C++ interoperability for mixed codebases.

The Swift Package Manager adds package access modifiers, macro target support, resource embedding, and enhanced registry publishing with signed packages and cross-compilation.

SwiftSyntax improves with better node naming, error recovery, incremental parsing, and community-driven contributions, while Windows support sees stabler concurrency, improved installer flexibility, and enhanced SDK coverage.