From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
Subject: bug#19816: 'guix environment' always downloads all the outputs of
	dependencies
Date: Sun, 20 Dec 2015 23:34:48 +0100
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To: Dave Thompson <davet@gnu.org>
Cc: 19816@debbugs.gnu.org

ludo@gnu.org (Ludovic Court=C3=A8s) skribis:

>>From <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=3D19641#16>:
>
> There=E2=80=99s another problem, though.  When a dependency is a multiple=
-output
> package, all its outputs are added to the environment, because
> =E2=80=98package->transitive-inputs=E2=80=99 discards the information of =
which output is
> needed.
>
> So for instance, both the =E2=80=98out=E2=80=99 and the =E2=80=98debug=E2=
=80=99 output of Coreutils end
> up being downloaded and added to the environment, even though only =E2=80=
=98out=E2=80=99
> is an input.
>
> Now, the problem is that =E2=80=98build-derivations=E2=80=99 can only bui=
ld *all* the
> outputs of the given derivation.  This could be worked around either:
>
>   1. by creating a =E2=80=9Csink=E2=80=9D derivation, for instance with
>      =E2=80=98profile-derivation=E2=80=99, that could refer precisely to =
the output(s)
>      needed; not ideal.

David, I think you had started looking at doing exactly this.  Do you
have a preliminary patch you=E2=80=99d like to post?

I understand you may be busy preparing the Lisp Game Jam now and I
wouldn=E2=80=99t want to distract you from that.  ;-)  If you have somethin=
g to
share, I=E2=80=99m happy to help start from there though (says the guy who =
sees
its =E2=80=98guix environment=E2=80=99 pointlessly downloading =E2=80=9Cdeb=
ug=E2=80=9D and =E2=80=9Cdoc=E2=80=9D outputs
again.)

Thanks,
Ludo=E2=80=99.