https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87121
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
<cmath> declares a std::pow function template that accepts integer types:
template<typename _Tp, typename _Up>
inline _GLIBCXX_CONSTEXPR
typename __gnu_cxx::__promote_2<_Tp, _Up>::__type
pow(_Tp __x, _Up __y)
{
typedef typename __gnu_cxx::__promote_2<_Tp, _Up>::__type __type;
return pow(__type(__x), __type(__y));
}
Since you're calling pow with two arguments of type 'int' the specialization
std::pow<int, int> is a perfect match, but ::pow(u64, int) is not (because
'u64' is not the same type as 'int').
