MarsSeed [1] filed a deletion request for ros-melodic-qt-gui-cpp [2]: EOL since mid-2022 [a], now broken, missing already deleted direct and transitive dependencies.
[a]: https://github.com/ros-visualization/qt_gui_core/tree/melodic-devel [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/ros-melodic-qt-gui-cpp/
