when will be QSharedFromThis for QSharedPointer?

[fsmoke]

class Object {
public:
  Object() { d = new ObjectPrivate; }
  Object(const Object &other) : d(other.d){ }
  int x() const { return d->x; }
  void setX(int x) { d->x = x; }
  Object childAt(int i) const { return d->children.at(i); }
  void addChild(Object o) { d->children.append(o); o.d->parent = *this; }
  Object& operator=(const Object &other) { d = other.d; return *this;}
private:
  QSharedPointer<ObjectPrivate> d;
};
 
class ObjectPrivate {
public:
  int x;
  Object parent;
  QList<Object> children;
};

class Object {
public:
  Object() { d = new ObjectPrivate; }
  Object(const Object &other) : d(other.d){ }
  int x() const { return d->x; }
  void setX(int x) { d->x = x; }
  Object childAt(int i) const { return d->children.at(i); }
  void addChild(Object o) { d->children.append(o); o.d->parent = *this; }
  Object& operator=(const Object &other) { d = other.d; return *this;}
private:
  QSharedPointer<ObjectPrivate> d;
};

class ObjectPrivate {
public:
  int x;
  Object parent;
  QList<Object> children;
};

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It's very interesting realization - it's pimpl

But I see BUG in this code ) - it seems recursive parent destruction - you must use QWeakPointer for parent.