Could you please delete https://aur.archlinux.org/packages.php?ID=52551 It is replaced by gtksourceviewmm in the community repository. The owner left a comment wondering how to have it deleted. I also filed a feature request https://bugs.archlinux.org/task/26253 to add libgtksourceviewmm3 to the gtksourceviewmm replaces array. Thanks, Cody