Проинициализировать массив во время компиляции

#include <utility>
 
constexpr unsigned long long fact(int n)
{
    unsigned long long res = 1;
    for (int i = 2; i <= n; ++i) res *= i;
    return res;
}
 
template <typename T, std::size_t N, size_t ... Indices>
void init(T (&arr)[N], std::index_sequence<Indices ...>)
{
    (arr[Indices] = fact(Indices))... ;
};
 
int main()
{
    unsigned long long factorials[10]; // = {fact(0), fact(1), fact(2), ..., fact(9)}
    init(factorials, std::make_index_sequence<10>());
}

constexpr unsigned long long factorials[10] = {fact(0), fact(1), fact(2), ..., fact(9)};
constexpr int val = factorials[5];

template <typename T, typename Func, size_t ... Indices>
constexpr std::array<T, sizeof ... (Indices)> make_array(Func func, std::index_sequence<Indices ...>)
{
    return {(0, func(Indices))... };
};
 
int main()
{
    constexpr auto ar = make_array<unsigned long long>(fact, std::make_index_sequence<10>());
    constexpr unsigned long long val = ar[5];
    static_assert(val == 120, "");
}