#include <QCoreApplication>

#include <QDebug>
#include <QSharedDataPointer>

class CarData : public QSharedData
{
public:
    int shit    = 1000;
    int * shit2 = nullptr;
};

class Car
{
public:
    QSharedDataPointer<CarData> d;
};


int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QSharedDataPointer<CarData> carDataAAA = QSharedDataPointer<CarData>(new CarData());
    QSharedDataPointer<CarData> carDataBBB = carDataAAA;

    Car car;
    car.d = carDataBBB;

    Car * carPtr = &car;

    if( carPtr->d->shit == 1000 )
    {
        qDebug() << "bbb";
    }

    if( !carPtr->d->shit2 )
    {
        qDebug() << "bbb";
    }


    return a.exec();
}