Question

Say we have the following two classes, A is the base class with virtual destructor and B is the derived class whose destructor doesn’t have ‘virtual’ qualifier. My question is, if I going to derive more classes from B, will B’s destructor automatically inherit the virtualness or I need to explicitly put ‘virtual’ before ‘~B() {…}’

class A
{
public:
    A() { std::cout << "create A" << std::endl;};
    virtual ~A() { std::cout << "destroy A" << std::endl;};
};

class B: A
{
public:
    B() { std::cout << "create B" << std::endl;};
    ~B() { std::cout << "destroy B" << std::endl;};
};

Answer 1

From C++ standard (section 10.3):

If a virtual member function vf is declared in a class Base and in
a class Derived, derived directly or indirectly from Base, […]
then Derived::vf is also virtual (whether or not it is so declared).

So yes.