一、variable `xxx' has initializer but incomplete type

程序段：

void MainWindow::testDemo()
{
    QObject *obj = new QPushButton;
    const QMetaObject *meta= obj->metaObject();
    QMetaClassInfo info = meta->classInfo(0);
    cout << info.name() <<endl;
}      

报错如下：

错误：

variable `xxx’ has initializer but incomplete type

原因：

解决办法：