default template arguments, C++ (vc++)

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//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x64

#include <type_traits>
#include <iostream>

template < typename FIRST = int, typename SECOND = double,
           typename THIRD = void, typename FOURTH = char >
struct example { /* ... */ };

enum param { FIRST, SECOND, THIRD, FOURTH };

namespace detail
{
    template < param, typename > struct example_maker ;

template < typename TYPE > struct example_maker<FIRST,TYPE>
    { using type = example<TYPE> ; } ;

template < typename TYPE > struct example_maker<SECOND,TYPE>
    { using type = example<int,TYPE> ; } ;

template < typename TYPE > struct example_maker<THIRD,TYPE>
    { using type = example<int,double,TYPE> ; } ;

template < typename TYPE > struct example_maker<FOURTH,TYPE>
    { using type = example<int,double,void,TYPE> ; } ;
}

template < param PARAM, typename TYPE >
using example_t = typename detail::example_maker<PARAM,TYPE>::type ;

int main()
{
    example_t< FIRST, long > ex1 ; // example< FIRST = int >
    static_assert( std::is_same< decltype(ex1), example<long> >::value, "" ) ;

example_t< SECOND, short > ex2 ; // example< SECOND = short >
    static_assert( std::is_same< decltype(ex2), example<int,short> >::value, "" ) ;

example_t< THIRD, char > ex3 ; // example< THIRD = char >
    static_assert( std::is_same< decltype(ex3), example<int,double,char> >::value, "" ) ;

example_t< FOURTH, std::ostream& > ex4 ; // example< FOURTH = std::ostream& >
    static_assert( std::is_same< decltype(ex4), example<int,double,void,std::ostream&> >::value, "" ) ;
    
    std::cout << "ok\n" ;
}

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Compilation time: 1,75 sec, absolute running time: 1,63 sec, absolute service time: 3,39 sec