QlineEdit信号映射问题

#include <QtWidgets>

class MyWidget : public QWidget
{
    Q_OBJECT

public:
    MyWidget(QWidget *parent = nullptr) : QWidget(parent)
    {
        QLineEdit *lineEdit = new QLineEdit(this);

        // 创建信号映射对象
        QSignalMapper *signalMapper = new QSignalMapper(this);

        // 连接信号映射的信号与槽函数
        connect(lineEdit, &QLineEdit::textChanged, signalMapper, static_cast<void (QSignalMapper::*)()>(&QSignalMapper::map));

        // 添加信号映射
        signalMapper->setMapping(lineEdit, "textChanged");

        // 连接信号映射的信号与槽函数
        connect(signalMapper, static_cast<void (QSignalMapper::*)(const QString &)>(&QSignalMapper::mapped), this, &MyWidget::handleTextChanged);

        QVBoxLayout *layout = new QVBoxLayout(this);
        layout->addWidget(lineEdit);
    }

public slots:
    void handleTextChanged(const QString &text)
    {
        qDebug() << "Text changed:" << text;
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    MyWidget widget;
    widget.show();

    return app.exec();
}

#include "main.moc"