[libc-commits] [libc] [libc][annex_k] Add errno_t. (PR #163094)

[Michael Jones via libc-commits]

https://github.com/michaelrj-google approved this pull request.

That's a good point, we can handle headergen changes in a separate PR.

As for overlay mode, I don't think we can assume that Annex K is provided by the system library (e.g. glibc doesn't provide it). We could add the checks for `__STDC_LIB_EXT1__` to our proxy headers as well, but I think the most straightforward solution might be to say that annex K functions are fullbuild only. If we really need them in overlay mode we can add that later.

For now I think this PR is fine as-is but we might want to revisit it later.

https://github.com/llvm/llvm-project/pull/163094