See http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1992, we can remove the catch of bad_alloc in _M_grow_words once we get to stage 1 of gcc 7, improving the solution for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68276.
And it's mine. :) I'll keep Jason up to date about the library needs here once Core makes issue 1992 ready.
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1992 is in C++17, what's the status of the front end?