struct copy_only {
    copy_only(copy_only const&) {} // note: not defaulted on first declaration
};
static_assert( std::is_move_constructible<copy_only>::value
             , "This won't trip" );

#include <type_traits>

template <typename T, bool P> struct is_movecopy_helper;

template <typename T>
struct is_movecopy_helper<T, false>
{
  typedef T type;
};

template <typename T>
struct is_movecopy_helper<T, true>
{
  template <typename U>
  struct Dummy : public U
  {
    Dummy(const Dummy&) = delete;
    Dummy(Dummy&&) = default;
  };
  typedef Dummy<T> type;
};

template <class T>
struct has_move_constructor
 : std::integral_constant<bool, std::is_class<T>::value &&
   std::is_move_constructible<typename is_movecopy_helper<T, std::is_class<T>::value>::type>::value> { };