'Get function return type in template

How can I get return type for any function passed to template?
I don't know how to convert between template<typename T> and template<typename Result, typename Args...>:

template<typename T>
void print_name(T f)
{
    static_assert(internal::is_function_pointer<T>::value
            || std::is_member_function_pointer<T>::value,
            "T must be function or member function pointer.");
    typename decltype(f(...)) Result; // ???
    typename std::result_of<T>()::type Result; // ???
    printf("%s\n", typeid(Result).name());
}

void f_void() {}
int f_int(int x) { return 0; }
float f_float(int x, int y) { return 0.f; }
struct X { int f(int x, float y) { return 0; } };

int main()
{
    print_name(f_void);
    print_name(f_int);
    print_name(f_float);
    print_name(&X::f);
    return 0;
}

How can i get type Result inside function print_name?

c++templatesc++14


Solution 1:[1]

as of C++ 20, the answer is

std::invoke_result_t<T>

Sources

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Source: Stack Overflow

Solution Source
Solution 1 noseems

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