Is it possible to overload a function that can tell a fixed array from a pointer?

Question

Motivation:

Almost for fun, I am trying to write a function overload that can tell apart whether the argument is a fixed-size array or a pointer.

Answer 1

This seems to work for me

#include 

template
std::enable_if_t::value>
foo(T) { std::cout << "pointer\n"; }

template
void foo(T(&)[sz]) { std::cout << "array\n"; }

int main()
{
  char const* c;
  foo(c);
  foo("hello");
}

Bonus std::experimental::type_traits:

using std::experimental::is_pointer_v;
std::enable_if_t>

---

Your comment made me try something even simpler

template void foo(T) { std::cout << "pointer\n"; }
template void foo(T(&)[sz]) { std::cout << "array\n"; }

Of course the problem here is that foo is now callable for any type, depends on how lax you want your parameter checking to be.

---

One other way is to (ab)use rvalue references

void foo(char const*&) { std::cout << "pointer\n"; }
void foo(char const*&&) { std::cout << "array\n"; }

Obviously it's not foolproof.