Diamond class.

Diamond.cpp

class X {};
class Y : public virtual X {};
class Z : public virtual X {};
class A : public Y , public Z {};
/*

X --> +-----------+
      | 1 bytes   | 
      +-----------+


                                    vtable

                           +-----------------------+
                           |     0 (top_offset)    |
                           +-----------------------+
Y/Z-->+----------+         | ptr typeinfo for Y/Z  |
      |  vtptr   |-------> +-----------------------+
      +----------+         
      | pad      |         
      +----------+


sizeof(D) = 48,align = 8                  vtable  

                                   +-----------------------+
                                   |   32 (vbase_offset)   |
                                   +-----------------------+
                                   |     0 (top_offset)    |
                                   +-----------------------+
                                   | ptr to typeinfo for D |
                      +----------> +-----------------------+
d --> +----------+    |            |         B::w()        |
      |  vtptr   |----+            +-----------------------+
      +----------+                 |         D::y()        |
      |pad  |b   |                 +-----------------------+
      +----------+                 |   16 (vbase_offset)   |
      |  vtptr   |---------+       +-----------------------+
      +----------+         |       |    -16 (top_offset)    |
      |  d  | c  |         |       +-----------------------+
      +----------+         |       | ptr to typeinfo for D |
      |  vtptr   |----+    +-----> +-----------------------+
      +----------+    |            |         C::x()        |
      | pad | a  |    |            +-----------------------+
      +----------+    |            |    0 (vbase_offset)   |
                      |            +-----------------------+
                      |            |   -32 (top_offset)    |
                      |            +-----------------------+
                      |            | ptr to typeinfo for D |
                      +----------> +-----------------------+
                                   |         A::v()        |
                                   +-----------------------+
*/
 int main()
{
    X x;
    Y y;
    Z z;
    A a;
}