override.cc

#include <stdio.h>
class A {
 public:
  virtual ~A() {}
  virtual void f(int) {}
};

class B : public A {
 public:
  void f(size_t) override {} // error
};

int main() {
  A* b = new B;
  b->f(0);

  return 0;
}

// clang++ -std=c++11 -Woverloaded-virtual a.cc
#include <stdio.h>
class A {
 public:
  virtual ~A() {}
  virtual void f(int) { printf("A::f()\n"); }
};

class B : public A {
 public:
  void f(size_t) { printf("B::f()\n"); } // warning
};

int main() {
  B b;
  b.f(0); // B::f()

  A* a = &b;
  a->f(0); // A::f()

  return 0;
}