Bug#844601: python-spyder: "from spyder.plugins.editor import Editor" hangs the machine

[Lisandro Damián Nicanor Pérez Meyer]

On sábado, 19 de noviembre de 2016 13:40:56 ART PICCA Frederic-Emmanuel wrote:
> > Hi Picca! Please next time you reassign a bug also CC the maintainer/team
> > that receives the bug, else we don't get this very text you wrote above
> > :-)
> sorry about that.

No problems, I've made the same mistake too :)
 
> > No, this not seems to be a Qt bug, and even less a Qt5 bug, as the lib
> > mentioned in the backtrace is from Qt4. By looking at the bug log I am
> > wondering if you are not happen to be mixing Qt4 and Qt5 in the same
> > package.
> I am not at all a Qt specialiste, so I red the first lines of the backtrace
> 
> #0  registerFont (fnt=0xbfffdd24) at text/qfontdatabase.cpp:1025
> #1  QFontDatabasePrivate::addAppFont (this=<optimized out>, fontData=...,
> fileName=...) at text/qfontdatabase.cpp:2436 #2  0xb47ea5dd in
> QFontDatabase::addApplicationFont (fileName=...) at
> text/qfontdatabase.cpp:2482 #3  0xb4c5bc0a in ?? () from
> /usr/lib/python2.7/dist-packages/PyQt5/QtGui.i386-linux-gnu.so #4 
> 0x800d6ba1 in call_function (oparg=<optimized out>, pp_stack=0xbfffde88) at
> ../Python/ceval.c:4352
> 
> then I seems to me that we where talking about PyQT5 (the binding) and then
> I deducted that the #0 where commin from qt5.
>
> How do I know from which library this is comming from.

From the original bug report (the only thing I had up to know): 

Few days ago, it was causing segmentation fault with the following backtrace:

        (gdb) bt
        #0  0x00007f5b8788cca3 in ?? () from
        /usr/lib/x86_64-linux-gnu/libQtGui.so.4

Note the 4 at the end, that comes from the SONAME of the lib. That's Qt4.

$ dpkg -S /usr/lib/x86_64-linux-gnu/libQtGui.so.4 

> I obtained these backtrace by installing the qt5 debug symbols and not the
> qt4 ones.

Then if the gdb backtrace in the original bug report is to be trusted then you are indeed mixing 
Qt4 and Qt5. And you can expect dragons for doing that ;-)

[snip]
> > Pass a null pointer to be dereferenced and you will get a segfault. And
> > that's purely missuse.
> 
> Yes this si why I like haskell ;)

Sadly haskell has no concept of ABI yet and everything needs a static build :-/

-- 
No subestimes el ancho de banda de un camión
cargado de cintas.
  Andrew S. Tanenbaum

Lisandro Damián Nicanor Pérez Meyer
http://perezmeyer.com.ar/
http://perezmeyer.blogspot.com/

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