From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ludovic =?UTF-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Subject: bug#40612: guix build system --dry-run is broken
Date: Wed, 15 Apr 2020 18:56:04 +0200
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References: <87wo6jax7c.fsf@netris.org> <20200414171632.41dae6fd@alma-ubu>
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To: =?UTF-8?Q?Bj=C3=B6rn_?= =?UTF-8?Q?H=C3=B6fling?= <bjoern.hoefling@bjoernhoefling.de>
Cc: 40612@debbugs.gnu.org

Hello!

Bj=C3=B6rn H=C3=B6fling <bjoern.hoefling@bjoernhoefling.de> skribis:

> On Mon, 13 Apr 2020 17:31:56 -0400
> Mark H Weaver <mhw@netris.org> wrote:
>
>> I guess this is related to the recent changes in graft handling, where
>> --dry-run (a.k.a. -n) no longer implies --no-grafts.  It's not working
>> well for me.  I hadn't updated my system since before those grafting
>> changes were made, and there's a lot for me to rebuild (I don't use
>> substitutes).  I was very surprised to see this small output:
>
> Hi Mark,
>
> I can confirm this behavior for "guix system". I'm on

Yeah, it has to do with the new build handler and the lack of
=E2=80=9Cparallelism=E2=80=9D when building the system derivation:

  https://lists.gnu.org/archive/html/guix-devel/2020-03/msg00337.html

I think we=E2=80=99ll improve it over time by introducing more parallelism
there.

Fundamentally though, we have to understand that =E2=80=98--dry-run=E2=80=
=99 can only
print the first derivation plans, not those that are dynamically built
as a function of build results.

Thanks,
Ludo=E2=80=99.