template<typename T>
struct A
{
  T v;
};
template<typename T>
union B
{
  A<T> a[2];
};
B<int> b;

.\main.cpp(18) : error C2621: member 'B<T>::a' of union 'B<T>' has copy constructor
        with
        [
            T=int
        ]
        .\main.cpp(21) : see reference to class template instantiation 'B<T>' being compiled
        with
        [
            T=int
        ]

R>template<typename T>
R>struct A
R>{
R>  T v;
R>};
R>template<typename T>
R>union B
R>{
R>  A<T> a[2];
R>};
R>B<int> b;
R>

template<typename T>
struct A
{
  T v;
};
template<typename T>
union B
{
  struct
  {
    A<T> a[2];
  }t;
};
B<int> b;

template<typename T>class test{
public:
    typedef struct {T v;} st;
    union {
        st  array[2];
        char data[500];
    };
};