1  // PR c++/106761
       2  
       3  template<class...>
       4  struct __and_;
       5  
       6  template<class, class>
       7  struct is_convertible;
       8  
       9  template<class... Ts>
      10  struct _TupleConstraints {
      11    template<class... Us>
      12    using __constructible = __and_<is_convertible<Ts, Us>...>;
      13  };
      14  
      15  template<class... Ts>
      16  struct tuple {
      17    template<class... Us>
      18    using __constructible
      19      = typename _TupleConstraints<Ts...>::template __constructible<Us...>;
      20  };
      21  
      22  tuple<int, int> t;