I've just checked in a patch to 3.7-stable that you might want to try
out; it silences a few clang warnings, including some that seem to
correspond to your error messages. You can find the source code here:
https://github.com/POV-Ray/povray/tree/hotfix/3.7.0_clang_warnings
Still, I would love to hear what g++ version you are using.
