[KDE/Mac] Review Request 120081: [OS X] prevent a crash after finishing a code difference review

[René J.V. Bertin]

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https://git.reviewboard.kde.org/r/120081/
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(Updated Sept. 7, 2014, 8:43 a.m.)


Status
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This change has been marked as submitted.


Review request for KDE Software on Mac OS X and KDevelop.


Repository: kdevplatform


Description
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On OS X, kdevelop would crash after clicking on the "Finish Review" button, at least when the path review tool was started through a project's git->differences. This crash occurred with the current stable release (kdevplatform 1.6.0) through the 4.7ß up to and including kdevplatform git/kde4-legacy.

The crash would be deep inside Qt, seemingly mouse action/event related. Googling the actual function in which the crash occurred led to the hypothesis a QObject derived object might be disposed of via `delete m_obj` instead of `m_obj->deleteLate()` as appears to be the correct way of doing things (http://qt-project.org/forums/viewthread/38406/#162801).

More details, with referring links and backtraces are here: https://bugs.kde.org/show_bug.cgi?id=338829

A single line change in the PatchReviewPlugin destructor, following this knowledge, seems indeed to be the required fix to prevent the crash. I have not made this a platform-specific change as the online information I found doesn't say anything about whether or not the requirement is valid for OS X only.

I ignore to what extent Qt5 has relaxed the disposal requirements on QObjects but presume it will continue to be a good idea to use ->deleteAll() . I presume Qt has some kind of garbage collection, if so, one should leave object disposal to the GC and not do it the hard way.


Diffs
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  plugins/patchreview/patchreview.cpp 2977c40 

Diff: https://git.reviewboard.kde.org/r/120081/diff/


Testing
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Works (i.e. no more crashing) under OS X 10.6.8, with kdelibs git/4.14 and the other dependencies at KDE/MacPorts 4.12.5 . kdevplatform and kdevelop are built using gcc 4.8.3 from MacPorts (due to the C++11 requirement).
The patch does not interfere with functionality on Linux.


Thanks,

René J.V. Bertin

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