title: Qt on Mac saying symbol(s) not found for architecture x86_64
body: <p>Hi I'm using Qt to create a Minesweeper game in macOS, and whenever I wrote some signals and slots to my classes my app won't compile. Qt says <code>ld: symbol(s) not found for architecture x86_64</code>
  So here's my code: </p>
  
  <pre><code>enum Status {
      virgin,
      flagged,
      questioned,
      revealed
  };
  class Cell : public QLabel
  {
      Q_OBJECT
  
  public:
      int atRow;
      int atCol;
      int content;//0 - 8 means the numbers of mines around the cell. -1 means it's a mine itself.
      bool isMine;
      Status status;
      Cell(int atRow, int atCol);
  
      Cell *NorthWest,
      *North,
      *NorthEast,
      *East,
      *SouthEast,
      *South,
      *SouthWest,
      *West;
  
  
  public slots:
      void mousePressEvent(QMouseEvent *event);
  
  };
  </code></pre>
  
  <p>I've seen many questions similar to mine but I was not able to solve this. I tried adding <code>CONFIG -= x86_64</code> but it's still not working. And I know it's the <code>MOC</code> thing but I don't know how to solve it.
  Someone help me please!</p>