There is no references in sources, only CMakeLists.txt requires it.
Thank you for reporting this bug in KDE software. As it has been a while since this issue was reported, can we please ask you to see if you can reproduce the issue with a recent software version? If you can reproduce the issue, please change the status to "REPORTED" when replying. Thank you!
Hello, I've just checked phonon-backend-gstreamer-4.10.0 sources and can still see that CMakeLists.txt requires libxml2, however I do not see anything XML related in any source file.
This backend for Phonon is no longer maintained or supported, and has not been for quite some time. Please use the VLC backend instead--which is the recommended and maintained replacement--and see if you can reproduce the issue there. If you can, please open a new bug report at https://bugs.kde.org/enter_bug.cgi?product=phonon-backend-vlc. Thanks a lot!
Hello Nate, I can see recent commits here https://github.com/KDE/phonon-gstreamer/commits/master. Are you sure that phonon-gstreamer is dead? I can even see some commits for building with Qt6 : https://github.com/KDE/phonon-gstreamer/commit/836275dc82e8bbe3bd312386242d02b654d59cb5
This backend is no longer maintained, sorry.