c – Q3ListView无法从Qt后备存储中取消注册或代码错误吗？

class Dialog : public QDialog
{
public:
  Dialog(QWidget* parent)
    : QDialog(parent)
    {
      new Q3ListView(this); // this will crash
//    new QWidget(this);    // this won't crash
    }
};

根据添加到Dialog的内容,删除Dialog实例时程序将崩溃(如代码段中的注释所示),但仅在主窗口的标志被修改时才会崩溃.以下是MainWindow类的代码,它使用Dialog：

class MainWindow : public QMainWindow
{
public:
  // the fact that the widget (dialog) below 
  // has no chance to show seems irrelevant. 
  // In the real scenario I have,the widget is shown on 
  // the screen and is closed by the user. 
  // I've just put the whole sequence of pieces of code 
  // that result from signal/slot calls,that in turn 
  // result from a point&click scenario in our application 
  // into the following function for brevity.
  void go()
    {        
      auto dialog = new Dialog(this);
      dialog->show();
      dialog->close();

      disableAlwaysOnTop();

      delete dialog; // or dialog->deleteLater();
    }

  void disableAlwaysOnTop()
    {
      setAttribute(Qt::WA_Resized,true);

      Qt::WindowFlags flags = windowFlags();
      setWindowFlags(flags ^ (Qt::CustomizeWindowHint | Qt::WindowStaysOnTopHint));

      setVisible(true);
    }
};

和main的实现：

int main(int argc,char** argv)
{
  QApplication app(argc,argv);
  MainWindow mainWindow;
  mainWindow.show();
  mainWindow.go();
  return app.exec();
}

所有线条似乎都必须重现崩溃.

这是Qt中的错误,还是我做错了什么？

允许手动删除小部件的子节点,并且它们应该自动从父节点取消注册,如下面手册中的引用所示.在我的实际案例中,窗口小部件被删除以从GUI中消失,并且它适用于其他窗口小部件组合.如上面的评论所示,更改删除对话框;到dialog-> deleteLater();没有帮助.

从Qt的后备存储中删除Q3ListView实例似乎存在问题,这里是堆栈跟踪：

QtGuid4.dll!QWidgetBackingStore::staticContents(QWidget * parent,const QRect & withinClipRect) Line 499 C++

QtGuid4.dll!QWidgetBackingStore::sync() Line 1200 C++

QtGuid4.dll!QWidgetPrivate::syncBackingStore() Line 1896 C++

QtGuid4.dll!QWidget::event(QEvent * event) Line 8694 C++

QtGuid4.dll!QMainWindow::event(QEvent * event) Line 1479 C++

QtGuid4.dll!QApplicationPrivate::notify_helper(QObject * receiver,QEvent * e) Line 4565 C++

QtGuid4.dll!QApplication::notify(QObject * receiver,QEvent * e) Line 4530 C++

QtCored4.dll!QCoreApplication::notifyInternal(QObject * receiver,QEvent * event) Line 955 C++

QtCored4.dll!QCoreApplication::sendEvent(QObject * receiver,QEvent * event) Line 231 C++

QtCored4.dll!QCoreApplicationPrivate::sendPostedEvents(QObject * receiver,int event_type,QThreadData * data) Line 1579 C++

QtCored4.dll!qt_internal_proc(HWND__ * hwnd,unsigned int message,unsigned __int64 wp,__int64 lp) Line 498 C++

[External Code]

QtCored4.dll!QEventDispatcherWin32::processEvents(QFlags flags) Line 823 C++

QtGuid4.dll!QGuiEventDispatcherWin32::processEvents(QFlags flags) Line 1216 C++

QtCored4.dll!QEventLoop::processEvents(QFlags flags) Line 150 C++

QtCored4.dll!QEventLoop::exec(QFlags flags) Line 204 C++

QtCored4.dll!QCoreApplication::exec() Line 1227 C++

QtGuid4.dll!QApplication::exec() Line 3824 C++

qt_bug.exe!main(int argc,char * * argv) Line 60 C++

而Qt的代码试图在堆栈跟踪中指示的行中使用指向已删除对象的指针：

for (int i = 0; i < count; ++i) {
    QWidget *w = staticWidgets.at(i);
    QWidgetPrivate *wd = w->d_func();
    if (!wd->isOpaque || !wd->extra || wd->extra->staticContentsSize.isEmpty()  // ****
        || !w->isVisible() || (parent && !parent->isAncestorOf(w))) {
        continue;
    }

(wd指向标有注释的行上的已删除对象).

免责声明：
我知道存在更优雅的解决方案,但这是遗留代码,并且根据Qt’s manual：

You can also delete child objects yourself,and they will remove themselves from their parents.

此代码有效.

我们在Windows 7(MSVC 2010 SP1,CL 16),Windows 8(MSVC 2013 U4,CL 18)和Fedora 20(GCC 4.8.3)上重现了这个问题.