QT初学者问题cannot take the address of an rvalue of type 'void'

这是个啥意思？看不太懂啥意思。

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->lineEdit,SIGNAL(returnPressed()),this,SLOT(on_commit_clicked()));
    connect(ui->concel,&QPushButton::clicked,this,&MainWindow::on_concel_clicked());
   
}
void MainWindow::on_commit_clicked()
{
    QString qname=ui->lineEdit->text();

    QProcess *myprocess=new QProcess(this);
    myprocess->start(qname);

}

void MainWindow::on_concel_clicked()
{
    this->close();
}

connect(ui->concel,&QPushButton::clicked,this,&MainWindow::on_concel_clicked());
改为
connect(ui->concel,&QPushButton::clicked,this,&MainWindow::on_concel_clicked);