From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?utf-8?Q?Ludovic_Court=C3=A8s?= <ludo@gnu.org>
Subject: Re: package systems, before and after the core-updates merge
Date: Sat, 19 Oct 2019 23:02:21 +0200
Message-ID: <87r238sb36.fsf@gnu.org>
References: <87sgnrqf62.fsf@cbaines.net>
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Hi,

Christopher Baines <mail@cbaines.net> skribis:

> One thing that I was aware of before the recent core-updates merge was
> that the Guix Data Service [1] didn't generate derivations for systems
> other than x86_64-linux and i686-linux, at least to the same extent as
> the master branch before the recent core-updates merge.

Indeed, see this bug fix that landed before the merge:

  https://git.savannah.gnu.org/cgit/guix.git/commit/?id=3Dbc60349b5bc58a0b8=
03df5adce1de6db82453744

> I think this is down to the use of package-transitive-supported-systems
> within the Guix Data Service, but the output of this function for a
> package can also be seen by running guix package --show.

The patch below fixes =E2=80=98guix show=E2=80=99 but it has a noticeable p=
erformance
impact that makes me thing something=E2=80=99s not quite right with memoiza=
tion
in =E2=80=98package-transitive-supported-systems=E2=80=99:


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diff --git a/guix/ui.scm b/guix/ui.scm
index 3e4bd5787e..426e517b54 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -1259,7 +1259,8 @@ WIDTH columns.  EXTRA-FIELDS is a list of symbol/value pairs to emit."
   (format port "version: ~a~%" (package-version p))
   (format port "outputs: ~a~%" (string-join (package-outputs p)))
   (format port "systems: ~a~%"
-          (string-join (package-transitive-supported-systems p)))
+          (string-join (filter (cut supported-package? p <>)
+                               %supported-systems)))
   (format port "dependencies: ~a~%"
           (match (package-direct-inputs p)
             (((labels inputs . _) ...)

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> Also, for the Guix Data Service, all I want to know is for a given
> package, is for which systems and targets a derivation can be reasonably
> computed. Maybe it is wrong to use package-transitive-supported-systems
> for this.

You can use =E2=80=98supported-package?=E2=80=99 as above.  This is also wh=
at (gnu ci)
does.

Let me know if this helps!

Ludo=E2=80=99.

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