Fibonacci C++14

#include <iostream>
#include <memory>
#include <vector>

constexpr int Fib(int n) {
    int a = 1;
    int b = 1;
    for (int i = 0; i < n; ++i) {
        int t = a + b;
        a = b;
        b = t;
    }
    return b;
}

template <class>
struct TD;

int main() {
    std::array<int, Fib(10)> a;
    TD<decltype(a)> t;
    return 0;
}