Comment by JonChesterfield

Trusting that the compiler docs correspond to reality is a bit of a risk here.

I lost a bunch of my evening to gcc refusing to find glibc headers and the docs wouldn't have helped me there. I did find a wontfix bugzilla from 2020 though, so that's nice.

The alternative would be to start stoically writing test programs and gradually reinvent part of autotools. Maybe run your conformance tests on the platforms that do have docs as well. Sounds like you may already be doing that :)