https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66962
--- Comment #11 from Eric Niebler <eric.niebler at gmail dot com> --- Removing the disjunction in the Constructible concept causes memory usage and compile time to drop to zero. The word from Andrew is that this is simply a quadratic algorithm. It is unknown whether a non-quadratic algorithm that handles disjunctions exists. Given that, I think we simply need to avoid concepts with disjunctions in STL2. :-(
