Another not-so-uncommon issue that crops up: packages DEPENDing upon themselves. Sometimes this is legit -- one of the Ada compilers, for example, DEPENDs upon || ( itself another-compiler ). Sometimes, however, it's the result of eclass screwups.
Typical example: you're coding a foo.eclass, that is used by foo and
various foo-extras. In the eclass, you set:
DEPEND=">=fnord-oink/foo-2.0"
Which, for foo-extras, is all well and good. However, for foo, which
also inherits the foo eclass, you get h0rked deps. Portage currently
mostly ignores circular dependencies -- however, relying upon this
behaviour probably isn't a good idea.
The following inside an eclass is totally legal:
if [[ "${PN}" != "foo" ]] ; then
DEPEND=">=fnord-oink/foo-2.0"
fi
Please give serious thought to doing this where applicable.
A similar issue: Portage lets you block yourself, and will ignore the
block. So if foo-2.0 has DEPEND="!fnord-oink/foo", you can still
install foo. (This is a separate thing from blocking specific versions
of yourself, which you may want to do on occasion if a package has a
weird upgrade cycle or is slotted.) Again, please try to avoid relying
upon this behaviour, since it's extremely confusing.
I'll prod on IRC / file bugs for any obvious cases where it's
definitely wrong. There's also a full list, complete with a whole load
of legit cases, at:
http://dev.gentoo.org/~ciaranm/tmp/find_self_circular_deps.txt
--
Ciaran McCreesh : Gentoo Developer (King of all Londinium)
Mail : ciaranm at gentoo.org
Web : http://dev.gentoo.org/~ciaranm
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