Plugin linking error with conan qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""

SGaist

Hi and welcome to devnet,

Are you sure your self built Qt has the wayland plugin ?
You can start your application with the QT_DEBUG_PLUGINS environment variable set to 1 to see what is happening with your version of Qt.
Also, do you have the development packages installed on your system ?

Remnant

qt.core.plugin.factoryloader: ignoring "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3" since plugins are disabled in static builds
qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem

Hi thank you for the quick reply this is the full output. I think I have all the required packages, even though I could not find an exhaustive list anywhere, but I tried to install all packages I came across in previous forum posts. I installed Qt with conan C++ package manager so I am not sure with what plugins it came, how can I check that or with what arguments on cmake can I impose that it build for wayland?

SGaist

You seem to be using a static build of Qt. Is that correct ?

Remnant

Yes I think that it is correct, it ran with default options which is that it be built static (I am pretty sure looking at the default options on the conan recipe github).

SGaist

Then you should follow the static plugin howto.

Remnant

Hello so I have looked around and I am not entirely sure what package I am supposed to link with

qt_import_plugins()

I have looked around and I have not found any good plugin to import I do not understand where to find the list of plugins to import to ensure bridging to wayland

SGaist

There's indeed no list however you can lookup for QXyzPlugin in Qt's sources under the src/plugins folders.

Remnant

.
├── _clang-format
├── cmake
├── CMakeLists.txt
├── CMakeUserPresets.json
├── coin
├── configure
├── configure.bat
├── configure.json
├── CONTRIBUTING.md
├── LICENSES
├── qt3d
├── qt5compat
├── qtactiveqt
├── qtbase
├── qtcharts
├── qtcoap
├── qtconnectivity
├── qtdatavis3d
├── qtdeclarative
├── qtdoc
├── qtgraphs
├── qtgrpc
├── qthttpserver
├── qtimageformats
├── qtlanguageserver
├── qtlocation
├── qtlottie
├── qtmqtt
├── qtmultimedia
├── qtnetworkauth
├── qtopcua
├── qtpositioning
├── qtquick3d
├── qtquick3dphysics
├── qtquickeffectmaker
├── qtquicktimeline
├── qtremoteobjects
├── qtscxml
├── qtsensors
├── qtserialbus
├── qtserialport
├── qtshadertools
├── qtspeech
├── qtsvg
├── qttools
├── qttranslations
├── qtvirtualkeyboard
├── qtwayland
├── qtwebchannel
├── qtwebengine
├── qtwebsockets
├── qtwebview
├── README.md
└── README.md.template

Hi so I am not entirely sure how the conan recipe is made but looking inside the src folder inside .conan2 I have the impression it has not been compiled exactly from a clone of the github. The only interesting thing I found was in the examples of qtwayland folder the inclusion of the Qt::WaylandCompositor in the CmakeLists but when I run cmake it does not find that package.

SGaist

GitHub is just a mirror.

If you want a full Qt checkout, there's a script in the qt5 repo that will do that properly. However that is not the subject here.

The plug-in you are after should be in the qtwayland submodule.
I was just thinking about something, you should have the libraries and plugins build somewhere on your filesystem. There you should be able to see exactly what is available.

Remnant

.So I have found the include dir with a little bit of grepping and this is what I have found inside the include files. there is Qt6::Wayland compositor and qtClient

├── QtConcurrent
├── QtCore
├── QtDBus
├── QtDesigner
├── QtDesignerComponents
├── QtDeviceDiscoverySupport
├── QtEglFSDeviceIntegration
├── QtEglFsKmsGbmSupport
├── QtEglFsKmsSupport
├── QtFbSupport
├── QtGui
├── QtHelp
├── QtInputSupport
├── QtKmsSupport
├── QtNetwork
├── QtOpenGL
├── QtOpenGLWidgets
├── QtPrintSupport
├── QtSql
├── QtTest
├── QtTools
├── QtUiPlugin
├── QtUiTools
├── QtWaylandClient
├── QtWaylandCompositor
├── QtWaylandEglClientHwIntegration
├── QtWaylandEglCompositorHwIntegration
├── QtWaylandGlobal
├── QtWidgets
├── QtWlShellIntegration
└── QtXml

Then This is my CMakeLists file

cmake_minimum_required(VERSION 3.15)
project(MyQtApp)
find_package(Qt6 REQUIRED COMPONENTS Core GUI WaylandCompositor)


set(CMAKE_CXX_STANDARD 17)


qt_import_plugins(Qt6::WaylandCompositor)

qt_add_executable(MyQtApp
    main.cpp)

target_link_libraries(MyQtApp PUBLIC Qt6::Core Qt6::Gui qt::qt Qt6::WaylandCompositor)

with a CMake Error saying package not found only on Qt6::WaylandCompositor or WaylandClient

and Qt6WaylandCompositor is also present in the cmake directory

Remnant

I am also a bit lost why does QLibraryInfo link to my .conan2 folder (does this indicate from where the binaries were built)?

SGaist

It was rather the librairies folder that you should have looked in.

I think the name of the plug-in is QWaylandIntegrationPlugin.

Remnant

Okay so I have found the solution to this question you have to export these environment vars
QT_QPA_PLATFORM_PLUGIN_PATH (somewhere in /usr/lib)
QT_PLUGIN_PATH (somewhere in /usr/lib)

then run your app and it should work. I still have some obscure issues but this got me further. I'll open another post if my other problems persist

Remnant

Thank you for having taken the time to answer

SGaist

Glad you found a solution and thanks for sharing ! :-)