How to add a QToolBar inside a QTabWidget

I have been trying to add a QToolBar inside a QTabWidget in order to achieve something like the image below, so that everytime I add a new QTabWidget I have also a related QToolBar inside it.

Everything seems to work fine, I create a QAction to link it to the QTabWidget and according to this post it seems to be possible to do that but the problem is that when I compile nothing shows up as shows below:

Below is what I have done so far:

mainwindow.h

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
    void onChangeTab(int index);
    void newTab();
    void closeTab(const int &index);
private slots:
    void on_addTabBtn_clicked();
    void on_tabWidget_tabCloseRequested(int index);
private:
    Ui::MainWindow *ui;
    QAction *addTab1;
    QToolBar *mToolBar1;
    QAction *addIconToolBar1;
};

mainwindow.cpp

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->tabWidget->clear();
    ui->tabWidget->setTabsClosable(true);
    ui->tabWidget->addTab(new QLabel("Add"), QString("Add"));
    ui->toolBar->setContextMenuPolicy(Qt::ActionsContextMenu);

    mToolBar1 = new QToolBar;
    addIconToolBar1 = new QAction;
    addIconToolBar1->setIcon(QIcon("qrc:/cardio.png"));
    ui->toolBar->addWidget(mToolBar1);
    ui->toolBar->addAction(addIconToolBar1);

    connect(ui->addTabBtn, &QPushButton::clicked, this, [&] { ui->tabWidget->addTab(new QLabel("Add"), QString("Add")); });
    connect(ui->tabWidget, SIGNAL(tabCloseRequested(int)), this, SLOT(closeTab(int)));

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_addTabBtn_clicked()
{
    int index = 0;
    if(index == this->ui->tabWidget->count() - 1) {
        newTab();
    }
}

void MainWindow::on_tabWidget_tabCloseRequested(int index)
{
    ui->tabWidget->removeTab(index);
}

I tried to solve the problem in many ways and researched what the cause might be. I came across several references such as this one, which is the most important I found as the user seems to be doing it but there is no reference to documentation or no example to code to understand/study through.

Thanks for pointing to the right direction to solve this issue.

You can simply do something like this, and it really works.

QToolBar *toolbar=new QToolBar("toolbar",ui->tab);
toolbar->addAction("action1");
toolbar->addAction("action2");

enter image description here