error: must use 'class' tag to refer to type 'XX' in this scope

在寫程序的時候，遇到了編譯器報錯 error: must use 'class' tag to refer to type 'thread' in this scope

void MainWindow::freeFreightUi(){

    freeFreight *free = new freeFreight(this);

}

需要指明是是一個類。

修改如下：

void MainWindow::freeFreightUi(){

    class freeFreight *free = new class freeFreight(this);

}