Comment by davidbalbert

The article references a few compiler extensions: __builtin_xnu_type_signature, __builtin_xnu_type_summary, and the xnu_usage_semantics attribute.

I can see references to these builtins in the latest xnu source[1], but not in upstream llvm[2], or Apple's forks of llvm[3] and clang[4].

It's been possible to build your own XNU[5] for a long time. Is that still possible now?

  [1]: https://github.com/apple-oss-distributions/xnu
  [2]: https://github.com/llvm/llvm-project
  [3]: https://github.com/apple-oss-distributions/llvmCore
  [4]: https://github.com/apple-oss-distributions/clang
  [5]: https://kernelshaman.blogspot.com/2021/02/building-xnu-for-macos-112-intel-apple.html