What does empty destructor do?

Question

I heard that empty destructor doesn't do anything and calling it doesn't remove the object. But in the code:

#include <iostream>
#include <set>


class a
{
public:
    ~a() 
    {}
std::set <int> myset;
};

int main()
{
a object;
object.myset.insert(55);
object.~a();
object.myset.insert(20);
std::cout << object.myset.size();
}

I get: "* glibc detected * /.app: double free or corruption (fasttop):" and then "ABORT".

If it matters I have c++11 flag enabled. So what does empty constructor actually do? It does something and I read it doesn't.

Answer 1

Your destructor may look empty, but it's actually destructing the member variables. In this case, it's destructing myset, so the subsequent insert(20) is crashing.

If your class had no non-POD member variables then the empty destructor would truly do nothing.