C++11 std::tuple to std::array conversion causes variadic template crash

Question

The following function, toArray, might one day convert a C++11 std::tuple into a C++11 std::array:

#include <tuple>
#include <array>

template <typename T, typename ...U>
std::array<T,sizeof...(U)>
toArray(std::tuple<U...>) {
  return std::array<T,sizeof...(U)>();
}

If I try to call toArray with the following code, under G++ 4.8 I can compile successfully. Compiling with Clang++ 3.2, however, crashes the Clang front-end. Is my code valid C++?

int main(int argc, char *argv[])
{
  auto tup = std::make_tuple(1,2,3,4,5,6,7,8);
  toArray<int>(tup);
  return 0;
}

Answer 1

It looks valid to me, and the finished version works fine with G++:

#include <redi/index_tuple.h>

template <typename T, typename... U, unsigned... N>
  std::array<T, sizeof...(U)>
  toArray2(std::tuple<U...>& t, redi::index_tuple<N...>) {
    return std::array<T, sizeof...(U)>{{ std::get<N>(t)... }};
  }

template <typename T, typename ...U>
  std::array<T, sizeof...(U)>
  toArray(std::tuple<U...> t) {
    return toArray2<T>(t, redi::to_index_tuple<U...>{});
  }

int main()
{
  auto tup = std::make_tuple(1,2,3,4,5,6,7,8);
  return toArray<int>(tup)[3] - 4;
}