c++ - C++17 find exact arguments of function and pass to template function

Question

I have a template function that I need to call, it looks something like this:

template<typename R, typename... A>
R fn_call(qword fn, A... args) {
    using T = R(*)(A...);
    fn = ...
    return ((T)fn)(args...);
}

#define wrapper_call(FUNC, ...) (fn_call<return_type_t<decltype(FUNC)>>((qword)FUNC, __VA_ARGS__))

Getting the return type for the function is simple, but I also need each argument. If I use it in its current state, the following will have issues because the stack parameters are not correct after r8.

void func(int a1, int a2, int a3, int a4, qword a5)

wrapper_call(func,0,0,0,0,0)

the 5th argument will be passed as a 4 byte int, when it must be a qword.

I am using C++17, and no standard library

question from:https://stackoverflow.com/questions/65879377/c17-find-exact-arguments-of-function-and-pass-to-template-function

Answer 1

template<class R, class...Args>
R fn_call_smart( R(*fn)(Args...), std::identity_t<Args>... args ) {
  return fn_call<R, Args...>(reinterpret_cast<qword>(fn), args...);
}

just call fn_call_smart, or rename it wrapper_call and strip out the macro.

fn_call_smart deduces the arguments from fn.

I don't see the point of your macro.