void Add(QRunnable* const Task_)
        {
            std::shared_ptr<QRunnable*> shared_ptr(Task_);
            std::weak_ptr<QRunnable*> weak_ptr(shared_ptr);

            MyDeque.push_back(weak_ptr);
            QThreadPool::globalInstance()->start(shared_ptr);//ТУТ ОШИБКА
        }

ошибка: no matching function for call to ‘QThreadPool::start(std::shared_ptr<QRunnable*>&)’
             globalInstance->start(shared_ptr);

void start(QRunnable *runnable, int priority = 0)

std::atomic<int> counter = {0};
...
int key = ++counter;

class MyTask: public QRunnable
    {
        const std::shared_ptr<MyTask> ThisTask;
       
        std::shared_ptr<MyTask> GetThisTask()
        {
            std::shared_ptr<MyTask> s_ptr(this);
            return s_ptr;
        }

    public:
        MyTask()
            :
            ThisTask(GetThisTask())
        {}
};