IMO this has nothing to do with alternatives; /usr/bin/g++ is part of the g++ package, it's not handled by alternatives. why not look first for packages just in main, then for packages in other sources?
-- recommends packages in universe in preference to packages in main https://launchpad.net/bugs/95598 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
