fork(1) download

copy

#include <string>
#include <type_traits>
 
void foo(int, int){}
void foo(std::string, std::string) {}
 
template <bool Val1, bool Val2, bool ...Rest>
struct And
{
	enum {value = And<Val1 && Val2, Rest...>::value};
};
template <bool Val1, bool Val2>
struct And<Val1, Val2>
{
	enum {value = Val1 && Val2};
};
 
template <typename ...Params, typename ...Args, typename = typename std::enable_if<
	And<std::is_convertible<Args, Params>::value...>::value
>::type>
void Invoke(void (*fn)(Params...), Args ...args){}
 
int main() {
	Invoke(&foo, "a", "b");
	return 0;
}

prog.cpp: In function ‘int main()’:
prog.cpp:24:23: error: no matching function for call to ‘Invoke(<unresolved overloaded function type>, const char [2], const char [2])’
  Invoke(&foo, "a", "b");
                       ^
prog.cpp:21:6: note: candidate: template<class ... Params, class ... Args, class> void Invoke(void (*)(Params ...), Args ...)
 void Invoke(void (*fn)(Params...), Args ...args){}
      ^~~~~~
prog.cpp:21:6: note:   template argument deduction/substitution failed:
prog.cpp:18:49: error: mismatched argument pack lengths while expanding ‘std::is_convertible<Args, Params>::value’
 template <typename ...Params, typename ...Args, typename = typename std::enable_if<
                                                 ^~~~~~~~

Standard output is empty