https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65122 --- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> --- IMHO the only sensible solution is in this direction: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3396.htm I hope Clark is still working on this...