Swift 6.4 Ships Subprocess 1.0, 40x Faster Wasm, Better Interoperability

Swift 6.4 is out with the stable Subprocess 1.0 library for launching external processes, non-copyable types like UniqueArray and UniqueBox, and Wasm code generation up to 40 times faster. It also improves C++20 and Java interoperability, adds @diagnose and @c/@implementation attributes, and makes Swift Build the default toolchain across platforms.

• Subprocess 1.0 offers a cross-platform API for launching external processes
• Wasm bridging via JavaScriptKit is up to 40x faster
• New UniqueArray, UniqueBox, Ref and MutableRef types cut copying
• Swift Build becomes the unified build toolchain on all platforms