pikatchu@localhost ~/build/vdrift-2007-03-23-src $ sudo emerge gpm ncurses
Calculating dependencies... done!
[nomerge      ] sys-libs/gpm-1.20.1-r5  USE="(-selinux)" 
[ebuild  N    ]  sys-libs/ncurses-5.6-r1  USE="gpm unicode -bootstrap -build -debug -doc -minimal -nocxx -trace" 
[ebuild  N    ]   sys-libs/gpm-1.20.1-r5  USE="(-selinux)" 
!!! Error: circular dependencies:

('ebuild', '/', 'sys-libs/ncurses-5.6-r1', 'merge') depends on
   ('ebuild', '/', 'sys-libs/gpm-1.20.1-r5', 'merge') (hard)
('ebuild', '/', 'sys-libs/gpm-1.20.1-r5', 'merge') depends on
   ('ebuild', '/', 'sys-libs/ncurses-5.6-r1', 'merge') (hard)

!!! Note that circular dependencies can often be avoided by temporarily
!!! disabling USE flags that trigger optional dependencies.