https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123976
--- Comment #243 from Iain Sandoe <iains at gcc dot gnu.org> --- I believe that I've found the issue - it only shows up with a non-parallel build (and that is a rare case these days). I'm testing a patch .. please halt comments on this BZ until that is done (move all other discussion elsewhere).
