Are there any specific reasons to use non-virtual destructors?

Question

As I know, any class that is designated to have subclasses should be declared with virtual destructor, so class instances can be destroyed properly when accessing them throu

Answer 1

Your question is basically this, "Why doesn't the C++ compiler force your destructor to be virtual if the class has any virtual members?" The logic behind this question is that one should use virtual destructors with classes that they intend to derive from.

There are many reasons why the C++ compiler doesn't try to out-think the programmer.

1. C++ is designed on the principle of getting what you pay for. If you want something to be virtual, you must ask for it. Explicitly. Every function in a class that is virtual must be explicitly declared so (unless its overriding a base class version).

2. if the destructor for a class with virtual members were automatically made virtual, how would you choose to make it non-virtual if that's what you so desired? C++ doesn't have the ability to explicitly declare a method non-virtual. So how would you override this compiler-driven behavior.

   Is there a particular valid use case for a virtual class with a non-virtual destructor? I don't know. Maybe there's a degenerate case somewhere. But if you needed it for some reason, you wouldn't be able to say it under your suggestion.

The question you should really ask yourself is why more compilers don't issue warnings when a class with virtual members doesn't have a virtual destructor. That's what warnings are for, after all.