Specifying dependencies among package outputs?

[Simon South <simon@simonsouth.net>]

Am I right in thinking there is no way to specify dependencies among the
outputs of a single package? To specify that a package's "out" output
depends on its "lib" output, for instance.

I ask because the Knot package (in gnu/package/dns.scm) builds a number
of logically distinct targets---daemon, libraries, administrative
utilities, general-purpose utilities, and documentation---and it would
be nice to separate at least some of these into individual outputs, in
part because we could then specify only the libraries as a dependency of
Knot Resolver.

However, Knot's daemon and utilities have the same dependency on its own
libraries, so pulling those into a separate "lib" output would be liable
to break everything else.

I've searched and can't find an example of this being done, nor can I
find any mention of it in the documentation. So I assume it's simply not
possible, and you would need to define an entirely separate package that
builds from the same source code---right?

-- 
Simon South
simon@simonsouth.net