The following well-formed code causes ICE on GCC 4.7.0 20120218 (experimental).

//////////////////////////////////////////////////////////////
template<typename T, T v>
struct integral_constant
{
  typedef T value_type;
  static constexpr value_type value = v;
  constexpr operator value_type() { return value; }
};

template<typename T>
struct B
{
  B()
  noexcept(integral_constant<bool, noexcept(T())>()) // <- ICE
    : v_()
  {}

  T v_;
};

int main()
{
  B<int> b;
}
//////////////////////////////////////////////////////////////

If I use the static constexpr `value' instread of the constexpr conversion function, the ICE disappears.