https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66789
--- Comment #1 from ktkachov at gcc dot gnu.org ---
Forgot to mention, bisection showed that it started with:
Author: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon Jan 26 23:42:39 2015 +0000
PR libstdc++/64368
* config/locale/gnu/numeric_members.cc (numpunct<char>::~numpunct(),
numpunct<wchar_t>::~numpunct()): Do not set _M_data->_M_grouping.
* src/c++11/cxx11-shim_facets.cc (numpunct_shim): Remove _M_grouping
and use cache's _M_grouping field.
(__numpunct_fill_cache): Likewise.
(__moneypunct_fill_cache): Improve comments.
