Swift for Wasm December 2025 Updates

In the last month of the year things are quieter, but we still have a few updates for you! The general theme is continued: toolchain bug fixes, steady stream of improvements to JavaScript and Swift interop, polishing Wasm debugging support in WasmKit, and updates to multiple libraries in the ecosystem.

These contributions and updates were provided by @kateinoigakukun, @krodak, @scottm, and @sliemeobn.

Swift Toolchain

  • [6.3 cherry-pick] Bump default stack size to 128K to fix OOM crash with Swift Testing swift-driver#2030.

JavaScriptKit

WasmKit

  • Debugger: support D detach command on LLDB session disconnect events #234;
  • Debugger: add support for reading Wasm locals #226;
  • Debugger: fix breakpoints in loops & recursive function #237;
  • Use lower Darwin platform versions (iOS 13 and macOS 14) in Package@swift-6.1.swift #233.

swift-corelibs-foundation

  • Include _CFIsMainThread for WASI platform #5292;
  • Use pthread API for NSLock for wasip1-threads target #5293.

Other Projects

  • NIOAsyncRuntime is a new Wasm-ready implementation of MultiThreadedEventLoopGroup and NIOThreadPool from NIOPosix, powered by Swift Concurrency. It is designed as a limited drop-in replacement for import NIOPosix when targeting WASI.

  • ElementaryUI had its inaugural 0.1.0 release with a minimal starter Vite template published.


Thank you for reading, and please feel free to add any comments or suggestions if we missed anything.

Happy holidays and happy New Year!

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