Does C++ virtual function call on derived object go through vtable?

Question

In the following code, it calls a virtual function foo via a pointer to a derived object. Will this call go through the vtable or will it call B::foo directly?

If it goes via a vtable, what would be a C++ idiomatic way of making it call B::foo directly? I know that in this case I am always pointing to a B.

Class A
{
    public:
        virtual void foo() {}
};

class B : public A
{
    public:
        virtual void foo() {}
};


int main()
{
    B* b = new B();
    b->foo();
}

Answer 1

Most compilers will be smart enough to eliminate the indirect call in that scenario, if you have optimization enabled. But only because you just created the object and the compiler knows the dynamic type; there may be situations when you know the dynamic type and the compiler doesn't.