Re: package systems, before and after the core-updates merge

[Ludovic Courtès]

Hi,

Christopher Baines <address@hidden> 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=bc60349b5bc58a0b803df5adce1de6db82453744

> 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 ‘guix show’ but it has a noticeable performance
impact that makes me thing something’s not quite right with memoization
in ‘package-transitive-supported-systems’:

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 . _) ...)

> 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 ‘supported-package?’ as above.  This is also what (gnu ci)
does.

Let me know if this helps!

Ludo’.