1struct VBase
2{
3  virtual void f () {}
4  VBase();
5  ~VBase();
6};
7
8struct  StreamBase
9{
10  virtual ~StreamBase() {}
11};
12
13struct  Stream : public virtual VBase, public StreamBase
14{
15  Stream();
16  virtual ~Stream() {}
17};
18
19struct DerivedStream : public Stream
20{
21  DerivedStream();
22};
23