# emerge -av --depclean

*** WARNING ***  Depclean may break link level dependencies.  Thus, it is
*** WARNING ***  recommended to use a tool such as `revdep-rebuild` (from
*** WARNING ***  app-portage/gentoolkit) in order to detect such breakage.
*** WARNING ***
*** WARNING ***  Also study the list of packages to be cleaned for any obvious
*** WARNING ***  mistakes. Packages that are part of the world set will always
*** WARNING ***  be kept.  They can be manually added to this set with
*** WARNING ***  `emerge --noreplace <atom>`.  Packages that are listed in
*** WARNING ***  package.provided (see portage(5)) will be removed by
*** WARNING ***  depclean, even if they are part of the world set.
*** WARNING ***
*** WARNING ***  As a safety measure, depclean will not remove any packages
*** WARNING ***  unless *all* required dependencies have been resolved.  As a
*** WARNING ***  consequence, it is often necessary to run
*** WARNING ***  `emerge --update --newuse --deep world` prior to depclean.

Calculating dependencies... done!

Dependencies could not be completely resolved due to
the following required packages not being installed:

>=dev-games/crystalspace-ps-1.1-r26674 required by games-rpg/planeshift-0.3.018-r6
=net-zope/zope-2.7* required by net-zope/plone-2.0.5-r2

Have you forgotten to run `emerge --update --newuse --deep world` prior to
depclean?  It may be necessary to manually uninstall packages that no longer
exist in the portage tree since it may not be possible to satisfy their
dependencies.  Also, be aware of the --with-bdeps option that is documented
in `man emerge`.

 * GNU info directory index is up-to-date.