https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- >From include/bits/stl_bvector.h" iterator #if __cplusplus >= 201103L insert(const_iterator __position, const bool& __x = bool()) #else insert(iterator __position, const bool& __x = bool()) #endif Looks like it has been there since std::vector<bool> was added back in 1999/2000 or so.