https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81878
--- Comment #39 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > Thinking about this and what Richard said before, If we go with that > approach the Include directories, Library paths etc will all be wrong. > It'll work but it's going to use a mix of the host and target compiler > includes/libs (because all -I and -L seem to be absolute paths). Isn't this > potentially dangerous? could end up with an ABI issue. In most practical cases -B../../ is just redundant with $(CXX). It's only when you configure like Richard that you may run into issues, but then we can assume that we're on Linux so the paths are OK I think.