title: "void value not ignored as it ought to be" - Qt/C++
body: <p>I have this simple "interface" for some plugins I want to develop, it looks like:</p>
  
  <pre><code>class TestPluginBase : public QObject
  {
    Q_OBJECT
  public:
      TestPluginBase();
      qint64 returnType(){return PluginType;}
  
  protected:
      qint64 PluginType;
  };
  </code></pre>
  
  <p>And some other classes which implement the "interface" like:</p>
  
  <pre><code>class TestPluginONE : public TestPluginBase
  {
  public:
      TestPluginONE() {this-&gt;PluginType =1;}
      qint64 returnType() {return this-&gt;PluginType;}
  };
  </code></pre>
  
  <p>Then I have another function which suppose to load different plugins:</p>
  
  <pre><code>qint64 TestPluginManager::loadPlugin(QObject *_plugin)
  {
  
    TestPluginBase *Plugin = qobject_cast&lt;TestPluginBase *&gt;(_plugin);
  
    if ( !Plugin )
          return 0;
  
      emit sigPluginLoaded(Plugin);
      return Plugin-&gt;returnType();
  
  }
  </code></pre>
  
  <p>But when building it I get <code>void value not ignored as it ought to be</code> and Qt creator says instantiated from the line I'm doing my cast... can't figure out what I'm doing wrong...any help/hint is appreciated.</p>