派生类VTable只具有基类虚函数。(Derived class VTable having only base class virtual functions. The derived class virtual functions are missing from derived class's vtable)

 这是一个非常基本的例子： 
 
class Base {
public:
    virtual void sayHi() const {}
    virtual void sayHello() {}
    virtual ~Base(){}
};

class Derived : public Base {
public:
    virtual void sayHi() {}
    virtual void sayHello() const {}
};

int main()
{
    Base *b = new Base();
    Base *d = new Derived();
    return 0;
}
 
 Base的vptr，在'b'中具有Base类的虚函数。 派生类对象'd'然而，在检查时，列出仅基础的虚函数。 这里的问题不是 ，为什么函数没有被覆盖，所以这里不需要使用override关键字。 问题是，为什么特定类的VTable不包含自己的虚函数？ 在这种情况下，为什么'd'的vtable不包含D :: sayHi和D :: sayHello？ 我愿意接受投票，但要勇敢地提及并说出原因。 
 
 编辑： 我知道这里的CONSTness看起来可能不对，但问题不在于覆盖。 
 
 这是在VS2012 Update4中特别尝试的 

Here is a very basic example:
 
class Base {
public:
    virtual void sayHi() const {}
    virtual void sayHello() {}
    virtual ~Base(){}
};

class Derived : public Base {
public:
    virtual void sayHi() {}
    virtual void sayHello() const {}
};

int main()
{
    Base *b = new Base();
    Base *d = new Derived();
    return 0;
}
 
The Base's vptr, in 'b' has virtual functions of Base class. The derived class object 'd' however, on inspection, list virtual functions of only base. The question here is not, why are the functions not being overridden so the use of override keyword isn't required here. The question is, why doesn't a particular class's VTable contain its own virtual functions? In this case why vtable of 'd' doesnt contain D::sayHi and D::sayHello? I am open to downvotes, but be brave to mention and tell the reason.
 
edit: I know that the CONSTness might look wrong here, but the question is not about overriding.
 
This is specifically tried out in VS2012 Update4

原文：https://stackoverflow.com/questions/31775752