title: A warning message "No matching signal for" when executing my application
body: <p>When executing my application some warning messages appear:<br>
  <code>QMetaObject::connectSlotsByName: No matching signal for on_actionUndo_triggered()</code>, 
  <code>QMetaObject::connectSlotsByName: No matching signal for on_actionRedo_triggered()</code></p>
  
  <p>I have implemented the rule <code>void on_objectName_signalName(signalParameters);</code> to the signal and slot that I have created and I don't know why that messages appear, note that the signal and slot work fine.</p>
  
  <p><strong>Declaration:</strong></p>
  
  <pre><code>class Widget : public QWidget {
      Q_OBJECT
  
  public:
      explicit Widget(QWidget *parent = 0);
      ~Widget();
  
  private:
      Ui::Widget *ui;
      QAction *actionUndo;
      QAction *actionRedo;
  
  private slots:
      void on_actionUndo_triggered();
      void on_actionRedo_triggered();
  };
  </code></pre>
  
  <p><strong>Definition:</strong></p>
  
  <pre><code>Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget) {
      ui-&gt;setupUi(this);   
      QVBoxLayout *layout = new QVBoxLayout(this);
      QMenuBar *menuBar = new QMenuBar();
      QMenu *editMenu = new QMenu("&amp;Edit");
      menuBar-&gt;addMenu(editMenu);
  
      this-&gt;actionUndo = new QAction("&amp;Undo", editMenu);
      this-&gt;actionUndo-&gt;setShortcut(QKeySequence::Undo);
      QObject::connect(this-&gt;actionUndo, SIGNAL(triggered()), this, SLOT(on_actionUndo_triggered()));
  
      this-&gt;actionRedo = new QAction("&amp;Redo", editMenu);
      this-&gt;actionRedo-&gt;setShortcut(QKeySequence::Redo);
      QObject::connect(this-&gt;actionRedo, SIGNAL(triggered()), this, SLOT(on_actionRedo_triggered()));
  
      editMenu-&gt;addAction(this-&gt;actionUndo);
      editMenu-&gt;addAction(this-&gt;actionRedo);
  
      this-&gt;layout()-&gt;setMenuBar(menuBar);
  }
  
  Widget::~Widget() {
      delete ui;
  }
  
  
  void Widget::on_actionUndo_triggered() {
  
  }
  
  void Widget::on_actionRedo_triggered() {
  
  }
  </code></pre>