[PyQt] Segmentation faults

[Mailing List SVR]

Il giorno gio, 05/08/2010 alle 03.10 -0400, Luke Campagnola ha scritto: 
> I believe I have run into a class of bugs in PyQt4. I originally found
> that QSpinBox.lineEdit() returns a QLineEdit instance which does not
> maintain its reference count properly after the original QSpinBox is
> deleted. Thus it is possible to either 1) have uncollectable LineEdits
> lingering in memory, or 2) crash the program by accessing the LineEdit
> (see example below). 
> 
> 
> The same bug also applies to:
>  - QAbstractSpinBox.lineEdit
>  - QComboBox.lineEdit, 
>  - QAbstractScrollArea.horizontalScrollBar
>  - QAbstractScrollArea.verticalScrollBar
>  - QTreeView.header
>  - QSplitter.handle
> 
> 
> .. and likely many others. In the best case, this bug causes minor
> memory leaks that few people are likely to notice. In the worst case,
> it causes crashes which are very difficult to debug if you don't have
> easy access to debugging symbols (ie using windows binaries). 
> 
> 
> $ python
> >>> from PyQt4.QtGui import *
> >>> a = QApplication([])
> >>> s = QSpinBox()
> >>> l = s.lineEdit()
> >>> del s
> >>> l.text()
> Segmentation fault

PySide is more forgiving and raise the following error:

RuntimeError: Internal C++ object already deleted.

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