Why do I get this error:

```
Error   2   error C2248: 'std::unique_ptr<_Ty>::unique_ptr' : cannot access private member declared in class 'std::unique_ptr<_Ty>' c:\program files (x86)\microsoft visual studio 11.0\vc\include\xmemory0 606 1   UNIQUE_PTR

```

when trying to Export this class with `__declspec(dllexport)`?

```
class __declspec(dllexport) A
{
private:
    std::stack<std::unique_ptr<int>> ints;
};

```

Im using vs2012