ebuild appears to pull in arts even with USE="-arts". running ~amd64.
games-board # emerge -av knights
These are the packages that I would merge, in order:
Calculating dependencies ...done!
[ebuild N ] kde-base/arts-3.5.0-r1 USE="alsa jack mp3 nas vorbis -arts -artswrappersuid -debug -esd -kdeenablefinal -xinerama" 927 kB
[ebuild N ] games-board/knights-0.6 USE="-arts -debug -kdeenablefinal -xinerama" 2,623 kB
Steps to Reproduce:
1. USE=-arts in make.conf
2. emerge knights
ebuild wants to pull in arts although has arts use flag, implying dependancy is optional.
If no required dependancy on arts, program to build and install normally without installing arts first. If arts really is a required dependancy, the use flag should be removed.
See Bug 73352, comment #7.
I posted a possible solution there:
*** Bug 123850 has been marked as a duplicate of this bug. ***