How to find where a package is installed by pacman?
I am not on my arch now to check, but I bet
pacman -Ql boost-libs or
pacman -Qk boost-libs will do the trick by providing you with the list of files installed by the package.
pacman -Q boost-libs #Display version pacman -Ql boost-libs #Display file list provided by local package pacman -Qk boost-libs #Check the local package database pacman -Qo /path/to/file #Check if the file is owned by any package