Bug 92 – QSpacerItem causing segmentation faults

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PySide is now a Qt Add-on and uses the Qt Project's JIRA Bug Tracker instead of this Bugzilla instance. This Bugzilla is left for reference purposes.

Bug 92 - QSpacerItem causing segmentation faults

Summary:

QSpacerItem causing segmentation faults

Status:	CLOSED FIXED

Product:	PySide
Classification:	Unclassified
Component:	QtGui
Version:	0.2.1
Platform:	All All

Importance:	P5 normal
Assigned To:	renato filho

URL:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2009-11-04 15:46 EET by Kamil Kisiel
Modified:	2010-03-24 16:30 EET (History)
CC List:	5 users (show)

See Also:

Attachments
Qt Designer UI file (8.67 KB, text/xml) 2009-11-04 15:46 EET, Kamil Kisiel	Details
pyside-uic output (10.81 KB, text/x-python-script) 2009-11-04 15:46 EET, Kamil Kisiel	Details
Simple application that loads the layout (429 bytes, text/x-python-script) 2009-11-04 15:47 EET, Kamil Kisiel	Details
QSpacerItem invalid destruction testcase (1.22 KB, text/x-python) 2009-11-19 13:55 EET, Hugues De Keyzer	Details
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Description Kamil Kisiel 2009-11-04 15:46:06 EET

Created attachment 23 [details]
Qt Designer UI file

I created a layout using Qt Designer and then attempted to load it in to a
simple application, which caused a segmentation fault. We determined that
commenting out the QSpacerItem instances in the pyside-uic output caused it to
work.

I'm using 0.2.1 on Ubuntu Jaunty.

Comment 1 Kamil Kisiel 2009-11-04 15:46:53 EET

Created attachment 24 [details]
pyside-uic output

Comment 2 Kamil Kisiel 2009-11-04 15:47:22 EET

Created attachment 25 [details]
Simple application that loads the layout

Comment 3 Kamil Kisiel 2009-11-04 15:48:01 EET

I should also note that I tried creating some other simple layouts with spacers
but did not have this problem

Comment 4 renato filho 2009-11-17 16:59:13 EET

This is working fine with PySide git HEAD. Can you test and confirm this?

Comment 5 Hugues De Keyzer 2009-11-19 13:55:51 EET

Created attachment 28 [details]
QSpacerItem invalid destruction testcase

It seems that this problem is related to incorrect ownership of the spacer. The
Qt documentation states that when an item is added to a QLayout with
QLayout::addItem() the ownership of the item is transferred to the layout. If a
QSpacerItem is created locally in a function (as is done in code generated from
a .ui), it will be destroyed at the end of the function, but it shouldn’t
(because it is owned by the QLayout). This works correctly with PyQt.

In the testcase, replacing the two lines by the commented ones prevents the
segmentation fault because the spacer is not destroyed (becaused it is an
instance variable).

Comment 6 renato filho 2009-11-19 15:32:37 EET

I tested this new example in PySide git HEAD version and works. Can somebody 
confirm this?

Comment 7 renato filho 2009-11-24 18:18:39 EET

fixed on PySide release 0.2.2.

Comment 8 Kamil Kisiel 2009-11-25 05:11:39 EET

I can verify this works for me now.

Aside: I notice that I did not receive any email updates regarding comments on
this ticket apart from the last comment notification and that it was closed.