post 0.9.7 snapshot: FTBFS on armel

[Didier Roche-Tolomelli]

See https://launchpadlibrarian.net/92782808/buildlog_ubuntu-precise-armel.compiz_1%3A0.9.7.0~bzr2995-0ubuntu1_FAILEDTOBUILD.txt.gz

[Tim Penhey (thumper)]

0.9.7.0~bzr2995/kde/window-decorator-kde4/kdecoration_plugins.cpp"
In file included from /usr/include/qt4/QtCore/qobject.h:50:0,
                 from /usr/include/qt4/QtGui/qwidget.h:46,
                 from /usr/include/qt4/QtGui/QWidget:1,
                 from /build/buildd/compiz-0.9.7.0~bzr2995/kde/window-decorator-kde4/kdecoration_plugins.h:42,
                 from /build/buildd/compiz-0.9.7.0~bzr2995/kde/window-decorator-kde4/kdecoration_plugins.cpp:34:
/usr/include/qt4/QtCore/qlist.h: In member function 'void QList<T>::node_destruct(QList<T>::Node*, QList<T>::Node*) [with T = QVariant]':
/usr/include/qt4/QtCore/qlist.h:757:5: instantiated from 'void QList<T>::free(QListData::Data*) [with T = QVariant]'
/usr/include/qt4/QtCore/qlist.h:732:9: instantiated from 'QList<T>::~QList() [with T = QVariant]'
/usr/include/kpluginfactory.h:355:73: instantiated from here
/usr/include/qt4/QtCore/qlist.h:433:28: error: cast from 'QList<QVariant>::Node*' to 'QVariant*' increases required alignment of target type [-Werror=cast-align]
cc1plus: all warnings being treated as errors
make[3]: *** [kde/window-decorator-kde4/CMakeFiles/kde4-window-decorator.dir/kdecoration_plugins.o] Error 1
make[3]: Leaving directory `/build/buildd/compiz-0.9.7.0~bzr2995/obj-arm-linux-gnueabi'
make[2]: *** [kde/window-decorator-kde4/CMakeFiles/kde4-window-decorator.dir/all] Error 2
make[2]: Leaving directory `/build/buildd/compiz-0.9.7.0~bzr2995/obj-arm-linux-gnueabi'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/build/buildd/compiz-0.9.7.0~bzr2995/obj-arm-linux-gnueabi'
dh_auto_build: make -j1 returned exit code 2
make: *** [build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2

We shouldn't be building the kde decorator should we?

[Sam Spilsbury (smspillaz)]

we build everything by default but it looks like a header file is broken on armel.

-DBUILD_KDE4=OFF -DCOMPIZ_DISABLE_PLUGIN_KDE=ON

[Didier Roche-Tolomelli (didrocks)]

Johnathan, it seems there is a cast issue in kdelibs (/usr/include/kpluginfactory.h), can you have a look from here so that compiz can build on armel as well?

Thanks :)

[Jonathan Riddell (jr)]

Such problems are hard to debug without having an actual ARM machine to test on

I have uploaded a kde4libs to a private ARM PPA with a possible fix/debugging aid so I'll see if that tells me anything more.

Worst case we could just drop compiz kde support, I suspect it's largely unused.

[Jonathan Riddell (jr)]

It's a cast-align error which is something to do with is something to do with how members in a struct are placed in memory. I have not come across one before and neither has agateau or an experienced ARM porter working on Maemo.

It could be worked around by turning off -Werror=cast-align but that might mean a problem appears later

It could be fixed by porting the code to use non-deprecated methods but I don't know if compiz kde plugins are well maintained.

Or it could be dropped from the package, I don't expect compiz kde plugins are much used now that KWin has compositing support.

[Jonathan Riddell (jr)]

Another KDE guy says he compiles without -Werror=cast-align, is causes too many problems

[Sam Spilsbury (smspillaz)]

Alright. Is there a -Wno-cast-align of some sort?

[Daniel van Vugt (vanvugt)]

Unaligned memory access of any sort will cause a crash on many (most?) CPU architectures (but not x86). It's best to fix the code, because even if you get around the warning it's then likely to crash on most non-x86 systems.

[Didier Roche-Tolomelli (didrocks)]

Let's unbock the situation right now and not build the kde decorator. As Jonathan told, kde guys are more willing to use kwin which is integrated to kde anyway. Later, we can reenable it if the compiz kde plugin is well maintained again.