fork download

copy

#include <tuple>
 
 
template<template<typename...> class T, typename>
struct instantiate_with_arg_pack { };
 
template< template<typename...> class T
        , template<typename...> class U
        , typename... Ts>
struct instantiate_with_arg_pack<T, U<Ts...>>
{
    using type = T<Ts...>;
};
 
template<class T>
using to_tuple = typename instantiate_with_arg_pack<std::tuple, T>::type;
 
 
template<typename T = int, typename U = double> struct exampl {};
 
 
template<typename T> struct TD;
 
 
int main()
{
    using Tuple = to_tuple<exampl<>>;
    TD< exampl<std::tuple_element_t<1, Tuple>, std::tuple_element_t<0, Tuple>> > td; // should swap default template parameters
}

prog.cpp: In function 'int main()':
prog.cpp:28:82: error: aggregate 'TD<exampl<double, int> > td' has incomplete type and cannot be defined
     TD< exampl<std::tuple_element_t<1, Tuple>, std::tuple_element_t<0, Tuple>> > td; // should swap default template parameters
                                                                                  ^

Standard output is empty