C++自定义GUI按钮问题

// 主窗口头文件
#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

signals:
    void customSignal();

private slots:
    void on_pushButton_clicked();
    void on_customSignal();

private:
    Ui::MainWindow *ui;
};

// 主窗口源文件
#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->pushButton, &QPushButton::clicked, this, &MainWindow::on_pushButton_clicked);
    connect(this, &MainWindow::customSignal, this, &MainWindow::on_customSignal);
}

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

void MainWindow::on_pushButton_clicked()
{
    emit customSignal();
}

void MainWindow::on_customSignal()
{
    // 自定义处理按钮单击事件的代码
}