c – 覆盖超类联合的子类联合ontop

class A { 
    ...
    union { int a; int b; };
 };

 class B : public A {
     ...
     int c; //<- Can this use the same storage as the union?
 };

一个更具体的例子是标记联合的想法,你希望有一个子类为联合添加一个类型.