libstdcxx/api/a13501.html

      template<typename _Tp, typename _Up>

      concept __not_overloaded_spaceship =  ! requires(_Tp&& __t, _Up&& __u)

          { operator<=>(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); }

      && ! requires(_Tp&& __t, _Up&& __u)

          { static_cast<_Tp&&>(__t).operator<=>(static_cast<_Up&&>(__u)); }

      && (is_same_v<_Tp, _Up>

          || (! requires(_Tp&& __t, _Up&& __u)

               { operator<=>(static_cast<_Up&&>(__u), static_cast<_Tp&&>(__t)); }

             && ! requires(_Tp&& __t, _Up&& __u)

               { static_cast<_Up&&>(__u).operator<=>(static_cast<_Tp&&>(__t)); }))

std::operator<=>
constexpr __detail::__synth3way_t< _Tp > operator<=>(const array< _Tp, _Nm > &__a, const array< _Tp, _Nm > &__b)
Definition array:312

std::__detail::__not_overloaded_spaceship
Definition concepts:414