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Subject: |
'guix environment' always downloads all the outputs of dependencies |
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Date: |
Sun, 08 Feb 2015 19:24:37 +0100 |
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Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) |
>From <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19641#16>:
There’s another problem, though. When a dependency is a multiple-output
package, all its outputs are added to the environment, because
‘package->transitive-inputs’ discards the information of which output is
needed.
So for instance, both the ‘out’ and the ‘debug’ output of Coreutils end
up being downloaded and added to the environment, even though only ‘out’
is an input.
Now, the problem is that ‘build-derivations’ can only build *all* the
outputs of the given derivation. This could be worked around either:
1. by creating a “sink” derivation, for instance with
‘profile-derivation’, that could refer precisely to the output(s)
needed; not ideal.
2. by using (build-things (list "/the/output/path")) and resorting to
‘build-derivations’ only if the ‘build-things’ call did nothing
(when passed a non-.drv store item, ‘build-things’ tries to
substitute and does nothing if that fails.)
Ludo’.
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Subject: |
Re: bug#19816: 'guix environment' always downloads all the outputs of dependencies |
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Date: |
Fri, 12 Feb 2016 22:07:31 +0100 |
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Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
"Thompson, David" <address@hidden> skribis:
> On Sun, Dec 20, 2015 at 5:34 PM, Ludovic Courtès <address@hidden> wrote:
>> address@hidden (Ludovic Courtès) skribis:
>>
>>>>>From <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19641#16>:
>>>
>>> There’s another problem, though. When a dependency is a multiple-output
>>> package, all its outputs are added to the environment, because
>>> ‘package->transitive-inputs’ discards the information of which output is
>>> needed.
>>>
>>> So for instance, both the ‘out’ and the ‘debug’ output of Coreutils end
>>> up being downloaded and added to the environment, even though only ‘out’
>>> is an input.
>>>
>>> Now, the problem is that ‘build-derivations’ can only build *all* the
>>> outputs of the given derivation. This could be worked around either:
>>>
>>> 1. by creating a “sink” derivation, for instance with
>>> ‘profile-derivation’, 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’d like to post?
>>
>> I understand you may be busy preparing the Lisp Game Jam now and I
>> wouldn’t want to distract you from that. ;-) If you have something to
>> share, I’m happy to help start from there though (says the guy who sees
>> its ‘guix environment’ pointlessly downloading “debug” and “doc” outputs
>> again.)
>
> The wip-environment-profiles branch has the code I've written thus
> far. I rebased it on master and resolved some conflicts in hopefully
> the right way. :)
>
> When I last hacked on it I got into a fully working state AFAICT, but
> the tests needed updating and that proved to be the most challenging
> part. If you're willing to finish it up, that would be awesome!
It took me a while but I’ve finally finished it and pushed as 779aa00.
I took a different strategy for the tests, which is to rely (in part) on
the output of ‘guix gc --references’ to determine whether the profile
contains all we need.
Thanks,
Ludo’.
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