Hello Carl,
> In my original non-minimal build, other things in <mutex> also cause > compilation > errors, which seem odd to me. This problem is not directly related to <mutex>. You'll have the same issue with <list>, <vector> or any other header from stdlib. As explained here: https://www.mail-archive.com/guix-devel@gnu.org/msg50183.html, the root cause is that clang cannot find libstdc++ headers which paths are hardcoded into gcc. We need to find a clean way to hardcode those paths into clang. However, I'm not sure on how to proceed cleanly. Mathieu
