const A *a = new B;
const A *a = new А;

class A
{
public:
    virtual ~A() { f(); }
public:
    virtual void f() const { std::cout << 1; }
};

class B: public A
{
public:
    ~B() { f(); }
private:
    virtual void f() const { std::cout << 2; }
};

int main()
{
    const A *a = new B;
    delete a;

    return 0;
}

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