title: QtConcurrent Map Cannot Use Class Method
body: <p>Hello I am trying to pass QList to QtConcurrent::Map function, but it fails to start and I don't understand why, maybe some one knows what might be the problem? </p>
  
  <p>This is the Class Method Code</p>
  
  <pre><code>void MainWindow::find_file(QStringList &amp;lst){
      QString fl_name = ui-&gt;ln_FlName-&gt;text();
      QRegExp exp;
      exp.setPattern(".*/("+ui-&gt;ln_FlName-&gt;text()+").*");
      QRegExp exp_2;
      exp.setPattern(".*/("+ui-&gt;ln_FlName-&gt;text()+")");
       foreach(const QString &amp;str,lst)
        {
          // Do some work...   
        }}
  </code></pre>
  
  <p>And this is the code when I try to execute this method</p>
  
  <pre><code>void MainWindow::on_btn_start_clicked(){
  QDir start_path(ui-&gt;ln_Dir-&gt;text());
  QList&lt;QFuture&lt;QStringList&gt; &gt; future_list;
  QList&lt;QStringList&gt; dirs_lists;
  QStringList temp_dir_list;
  QList&lt;QString&gt; lst_str;
  foreach(const QFileInfo fl_inf,start_path.entryInfoList(QDir::NoDotAndDotDot|QDir::Dirs))
  {
      if(fl_inf.isDir())
      {
          //Here I use QtConcurrent::run with other method and it works fine
  
          QFuture&lt;QStringList&gt;ft;
          ft=QtConcurrent::run(this,&amp;MainWindow::File_Search,fl_inf.filePath());
          future_list.append(ft);
          num_ft+=1;
          temp_dir_list.append(fl_inf.filePath());
          lst_str.append(fl_inf.filePath());
      }
  
  
  }
  dirs_lists.append(temp_dir_list);
  long long int sum = 0;
  for(int i=0;i&lt;future_list.count();i++)
  {
  
      sum += future_list.at(i).result().count();
      dirs_lists.append(future_list.at(i).result());
  }
  
  
  //But this doesn't want to work 
  
  QFutureWatcher&lt;void&gt; ft_watcher;
  ft_watcher.setFuture(QtConcurrent::map(dirs_lists,&amp;MainWindow::find_file));
  }
  </code></pre>
  
  <p>And the compiler outputs this errors:</p>
  
  <blockquote>
    <p>error: no matching function for call to 'map(QList&amp;, )'
         QtConcurrent::map(dirs_lists,MainWindow::find_file);
                                                           ^</p>
  </blockquote>
  
  <p>And</p>
  
  <blockquote>
    <p>error: no match for call to '(QtConcurrent::MemberFunctionWrapper1) (QStringList&amp;)'
             map(*it);
             ^</p>
  </blockquote>