text: #include <memory>
  
  struct Foo {
    int a;
  };
  
  int main(int argc, char **argv) {
    std::shared_ptr<Foo> s(new Foo);
    s->a = 3;
    std::weak_ptr<Foo> w = s;
    return s->a; // Set break point at this line.
  }
  