[Interest] Double free in QItemDelegate editor

[Kyle Edwards]

On 9/4/20 12:06 PM, Kyle Edwards wrote:
> Interestingly, the stack trace shows that the widget's destructor is 
> being called within one of its own methods. Whether it's the same 
> widget or just the same class but a different instance, I'm not sure 
> (ASAN's stack trace doesn't print this information.) 

After some more investigation, I've learned more about the nature of the 
problem.

The createEditor() override returns a button which, when clicked, opens 
a file dialog (through QFileDialog::getOpenFileName() - this will be 
important in a bit). The opening of this dialog causes the editor to 
lose focus, which result in QAbstractItemDelegate emitting its 
closeEditor() signal, which in turn destroys the editor. The destroying 
of the editor also attempts to delete the file dialog, since it's a 
child of the editor. However, the file dialog was allocated on the stack 
by QFileDialog::getOpenFileName(). So, attempting to delete the 
stack-allocated dialog results in a crash.

So I guess the question is, how do I prevent QAbstractItemDelegate from 
emitting closeEditor() when the file dialog opens? Either that or 
prevent closeEditor() from actually closing the editor... I see 
something in QAbstractItemView::closeEditor() about an editor being 
"persistent", does that have anything to do with this?

Kyle