GNU bug report logs - #39996
foreign distro: QT5 loads/searchs plugins from wrong location

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Hartmut Goebel <h.goebel <at> crazy-compilers.com>
To: bug-guix <bug-guix <at> gnu.org>
Subject: foreign distro: QT5 loads/searchs plugins from wrong location
Date: Mon, 9 Mar 2020 10:31:32 +0100

[Message part 1 (text/plain, inline)]

I just packages a simple GUI application using pythonqt5 and
python-poppler-qt. When running it fails with:

Could not load the Qt platform plugin "xcb" in "" even though it was
found.

When running with QT_DEBUG_PLUGINS=1 it reveals the cause:

QFactoryLoader::QFactoryLoader() checking directory path
"/usr/lib64/qt5/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at
"/usr/lib64/qt5/plugins/platforms/KWinQpaPlugin.so"
Found metadata in lib
/usr/lib64/qt5/plugins/platforms/KWinQpaPlugin.so, metadata=
[… many lines skipped …]

Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path
"/gnu/store/608bvypsh90c58apvd2cgg3m9l2pwjqn-python-3.7.4/bin/platforms"
...
Cannot load library /usr/lib64/qt5/plugins/platforms/libqxcb.so:
(libQt5XcbQpa.so.5: cannot open shared object file: No such file or
directory)
QLibraryPrivate::loadPlugin failed on
"/usr/lib64/qt5/plugins/platforms/libqxcb.so" : "Cannot load library
/usr/lib64/qt5/plugins/platforms/libqxcb.so: (libQt5XcbQpa.so.5:
cannot open shared object file: No such file or directory)"

Looks like the plugin is search in the wrong location and also the list
of plgins.

-- 
Regards
Hartmut Goebel

| Hartmut Goebel          | h.goebel <at> crazy-compilers.com               |
| www.crazy-compilers.com | compilers which you thought are impossible |

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Message #8 received at 39996 <at> debbugs.gnu.org (full text, mbox):

From: Marius Bakke <mbakke <at> fastmail.com>
To: Hartmut Goebel <h.goebel <at> crazy-compilers.com>, 39996 <at> debbugs.gnu.org
Subject: Re: bug#39996: foreign distro: QT5 loads/searchs plugins from wrong
 location
Date: Tue, 10 Mar 2020 20:24:27 +0100

[Message part 1 (text/plain, inline)]

Hartmut Goebel <h.goebel <at> crazy-compilers.com> writes:

> I just packages a simple GUI application using pythonqt5 and
> python-poppler-qt. When running it fails with:
>
> Could not load the Qt platform plugin "xcb" in "" even though it was
> found.

Does it help if you wrap it with QT_PLUGIN_PATH, as we do with some
other KDE applications?

Alternatively, installing 'qtbase' with the other packages should set up
the relevant search paths.

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Message #11 received at 39996 <at> debbugs.gnu.org (full text, mbox):

From: Hartmut Goebel <h.goebel <at> crazy-compilers.com>
To: Marius Bakke <mbakke <at> fastmail.com>, 39996 <at> debbugs.gnu.org
Subject: Re: bug#39996: foreign distro: QT5 loads/searchs plugins from wrong
 location
Date: Wed, 11 Mar 2020 09:55:37 +0100

[Message part 1 (text/plain, inline)]

Hi Marius,
> Does it help if you wrap it with QT_PLUGIN_PATH, as we do with some
> other KDE applications?

I was able to work-around this by setting QT_PLUGIN_PATH. (Installing
qtbase has worked, too, btw)

Nevertheless I which this would not be necessary. I'd expect the qtbase
to find the plugins and platform-plugins coming with itself. (As far as
I've seen from the Nixpkg, nix has the same issues, so no solution to
copy from there.)

-- 
Regards
Hartmut Goebel

| Hartmut Goebel          | h.goebel <at> crazy-compilers.com               |
| www.crazy-compilers.com | compilers which you thought are impossible |

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