Installed Qt6.8.2 - now cmake cannot find Qt6 components

Tom asso

@SGaist - I removed the cache file, problem still persists. cmake output says:

Found package configuration file:

   /home/oreilly/Qt6.8/Tools/QtDesignStudio/qt6_design_studio_reduced_version/lib/cmake/Qt6/Qt6Config.cmake

 but it set Qt6_FOUND to FALSE so package "Qt6" is considered to be NOT
 FOUND.  Reason given by package:

 Failed to find required Qt component "Quick".

Why is component "Quick" not found? Is it not installed by default by the online installer?

SGaist

Wait...
Why is it searching in Design Studio ?
Are you sure the kit you are trying to use is pointing to the Qt 6.8.2 that you installed ?

Tom asso

@SGaist I installed Qt 6.8.2 into /home/oreilly/Qt6.8.
I set CMAKE_PREFIX_PATH to /home/oreilly/Qt6.8/6.8.2/gcc_64/lib/cmake/Qt6CoreTools/ - that seems correct, right?

SGaist

No, you should have stopped at the cmake level.

Tom asso

@SGaist EDIT: I see, thanks now cmake works!
CMAKE_PREFIX_PATH=/home/oreilly/Qt6.8/6.8.2/gcc_64/lib/cmake/

Tom asso

But now I want to add Graphs component:

find_package(Qt6 COMPONENTS Gui Quick Graphs REQUIRED)

But cmake fails:

-- Could NOT find Qt6Graph (missing: Qt6Graph_DIR)
CMake Error at src/qt-guilib/CMakeLists.txt:25 (find_package):
  Found package configuration file:

    /home/oreilly/Qt6.8/6.8.2/gcc_64/lib/cmake/Qt6/Qt6Config.cmake

  but it set Qt6_FOUND to FALSE so package "Qt6" is considered to be NOT
  FOUND.  Reason given by package:

  Failed to find required Qt component "Graph".

  Expected Config file at
  "/home/oreilly/Qt6.8/6.8.2/gcc_64/lib/cmake/Qt6Graph/Qt6GraphConfig.cmake"
  does NOT exist

I looked in the online installer, didn't see any "custom" installation for Graphs - How can I install it?

Thanks!

SGaist

There's something wrong somewhere. Your components show graphs yet cmake is warning about graph. Did you forget the s in your CMakeLists.txt ?

Tom asso

@SGaist
I tried both "Graph" and "Graphs" - here is output from "Graphs":

Found package configuration file:

   /home/oreilly/Qt6.8/6.8.2/gcc_64/lib/cmake/Qt6/Qt6Config.cmake

 but it set Qt6_FOUND to FALSE so package "Qt6" is considered to be NOT
 FOUND.  Reason given by package:

 Failed to find required Qt component "Graphs".

 Expected Config file at
 "/home/oreilly/Qt6.8/6.8.2/gcc_64/lib/cmake/Qt6Graphs/Qt6GraphsConfig.cmake"
 does NOT exist

Tom asso

The problem is that in Qt 6.8.2, the Graphs headers, cmake and libraries components are only found in the Tools/QtDesignStudio directory; e.g. on my system in $HOME/Qt6.8/Tools/QtDesignStudio/qt6_design_studio_reduced_version. But I do not use QtDesignStudio as I've found it to be very buggy in ubuntu 22.04.3.
It's a pain-in-the-neck but I had to manually create symbolic links in order to build with Qt6 Graphs on my system:

ln -s ~/Qt6.8/Tools/QtDesignStudio/qt6_design_studio_reduced_version/lib/cmake/Qt6Graphs ~/Qt6.8/6.8.2/gcc_64/lib/Qt6Graphs

ln -s ~/Qt6.8/Tools/QtDesignStudio/qt6_design_studio_reduced_version/lib/libQt6Graphs.so.6.8.0 ~/Qt6.8/6.8.2/gcc_64/lib/libQt6Graphs.so.6.8.0

ln -s ~/Qt6.8/Tools/QtDesignStudio/qt6_design_studio_reduced_version/include/QtGraphs ~/Qt6.8/6.8.2/gcc_64/include/QtGraphs

Perhaps I could avoid making these symbolic links through clever use of environment variables, but the above seems to work now.

I assume and hope that the Graphs components will be moved from Tools/QtDesignStudio into the "standard" directory (e.g 6.8.x/) in future releases.

Tom asso

Almost there...
I add the following to my app's qml file as described here:

import QtGraphs

I build my app with cmake as described above but when I run it, it generates an error and segfaults:

module "QtGraphs" is not installed
Segmentation fault (core dumped)

What am I missing now?
Thanks!

SGaist

Did you check that you installed the optional components in the installer ?

Tom asso

@SGaist - I selected "Qt 6.8 for desktop development" in the online installer. As noted above the downloaded components included Qt Graphs code and libraries under the Tools/QtDesignStudio/ directory - I had to make some symbolic links to those in order to build my code (I do not use QtDesignStudio). I can compile and link my application, but "import QtGraphs" fails at runtime. Where are the "optional components" you refer to? If I select "Custom Installation" instead of "Qt 6.8 for desktop development" I don't see options obviously related to Qt Graphs.

jsulm

@Tom-asso said in Installed Qt6.8.2 - now cmake cannot find Qt6 components:

I had to make some symbolic links to those in order to build my code (I do not use QtDesignStudio)

This is wrong Qt modules are not installed in Tools/QtDesignStudio!
"Where are the "optional components" you refer to?" - in the Qt installer or Qt maintenance tool.

Tom asso

OK double-checking that I'm using correct version of the installer...

Tom asso

OK I was using online-installer and MaintenanceTool incorrectly. For my own edification/notes, the "correct" way for Qt desktop seems to be:

Run installer, specify "Qt" as Qt destination directory, then specify "Qt 6.8 for desktop development"
Run downloaded Qt/MaintenanceTool , select Add or remove components
Qt->Qt6.8.2->Additional libraries->Qt Graphs (plus preselected libraries)

Thanks for your help everyone.