Hello everyone. I hava a small and maybe useless question about the cplusplus standard. Maybe there are some experts can help me. Here is the code.

#include <iostream>
struct A
{
      A(){} // not trivial
      ~A(){}
      void f1()const
      {
            std::cout << this << '\n';
      }
      void f2(this const A& self)
      {
            std::cout << &self << '\n';
      }
};

void f3(const A& a)
{
      std::cout << &a << '\n';
}

int main()
{
      A a{};
      a.~A();
      a.f1(); // UB!
      f3(a); // OK
      a.f2(); // UB or not?
      auto p = &A::f2;
      p(a); // UB or not?
      p = f3;
      p(a); // OK
      new(std::addressof(a))A{}; // OK
}