struct Inner {
  int field = 0;
  void Modify() {
    field++;
  }
};

struct Outer {
  Inner inner;
};

class MyClass {
public:
  Outer outer;
  Inner& inner; // refers to outer.inner, for convenience

  MyClass() : inner(outer.inner) {}

  void ConstMethod() const {
    inner.Modify();  // oops; compiles
  }
};

int main() {
    const MyClass myclass;
    std::cout << myclass.outer.inner.field << "n";  // prints 0
    myclass.ConstMethod();
    std::cout << myclass.outer.inner.field << "n";  // prints 1
}