Bug 451143

SUMMARY
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Hello. I'm using latest flatpak kdevelop package on kubuntu 20.04 with latest updates. I'm having problem with absent syntax highlighting on a C++ project. General code tools like find uses and refactoring are also unavailable. Background parser progress bar shows, moves to 100% and fades.

If you launch kdevelop flatpak package from terminal you will see an error like:
kdevplatform.shell: Can't load plugin "kdevclangsupport" because a factory to load the plugin could not be obtained: Cannot load library /app/lib/plugins/kdevplatform/35/kdevclangsupport.so: (libclang.so.12: cannot open shared object file: No such file or directory)

Juding by locate (updatedb performed beforehand), libclang.so.12 is nowhere to be found in flatpak directories. I've manually installed llvm12 through apt but it does not change anything.

Thanks.

STEPS TO REPRODUCE
1. Install kdevelop from flatpak on Kubuntu 20.04 or 21.10
2. Open any c++ project
3. Syntax highlighting and code warnings, errors and other things (find uses, refactor) are not available. 

OBSERVED RESULT
libclang.so.12 is not present, kdevelop fails to load kdevclangsupport plugin and fails to provide syntax highlighting and other features.

EXPECTED RESULT
libclang.so.12 should probably be installed with kdevelop or in its dependencies.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Kubuntu 20.04, Plasma 5.18.8
(available in About System)
KDE Plasma Version: 5.18.8
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8

ADDITIONAL INFORMATION