https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118341
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The debug bitset also does checking in its reference type, but only for C++98:
// In C++11 we rely on normal reference type to preserve the property
// of bitset to be use as a literal.
// TODO: Find another solution.
#if __cplusplus >= 201103L
typedef typename _Base::reference reference;
#else
// bit reference:
class reference
: private _Base::reference
, public __gnu_debug::_Safe_iterator_base
{
That should be revisited.
