C++11 version of https://gist.github.com/tristan0x/5bd947e8d89a187a6cbf8747b05c3ea3

initializer_list_helper.cpp

#include <initializer_list>

template <int... Values>
struct integer_sequence {};

template <std::size_t Size, int...Accu>
struct ones_traits {
    using type = typename ones_traits<Size - 1, 1, Accu...>::type;
};

template <int... Accu>
struct ones_traits<0, Accu...> {
      using type = integer_sequence<Accu...>;
};

template <typename T, int... Ones>
std::initializer_list<T> il_impl(T value, const integer_sequence<Ones...>&) {
    static const auto array = { (Ones, value)... };
    return array;
}

template <std::size_t Size, typename T>
std::initializer_list<T> il(T value) {
    return il_impl<T>(value, typename ones_traits<Size>::type());
}

// --------------

#include <iostream>
#include <iterator>
#include <vector>

template <typename T>
void print(const std::vector<T>& v) {
    std::copy(v.begin(), v.end(),
              std::ostream_iterator<T>(std::clog, ", "));
    std::clog << '\n';
}

template <typename T>
void test(const std::initializer_list<T>& il) {
    std::vector<T> v(il);
    print(v);
}

int main() {
    test(il<3>(3));
    test(il<3>(3.14957));
}