[bug#49196] [PATCH] import: utils: 'recursive-import' skips unfound packages

[Sarah Morgensen via Guix-patches via <guix-patches@gnu.org>]

Hello,

Thanks for the review!

zimoun <zimon.toutoune@gmail.com> writes:

> Indeed, there is an inconsistency betweem all the recursive importers.
> An attempt to fix this is done by [1].
>
> 1: <http://issues.guix.gnu.org/issue/45984>

Thanks, that was a good read. With context, I see where you're coming
from. I agree that the direction to take with these importers is to
unify and standardize.

The goal of this patch is just to allow recursive import to provide a
usable result despite some failures, when the importer supports it. I'd
rather hunt down one package than 20+ :) This may make reporting errors
more difficult, but I think the use-case is worth it.

> ...however, I am not convinced this fixes the issue.  Compare:
>
> $ guix import go do-not-exist -r
>
> with:
>
> $ ./pre-inst-env guix import go do-not-exist -r

Good catch. I did not think to handle the toplevel package not being
found! This actually leads to making this a much simpler patch...

--8<---------------cut here---------------start------------->8---
-  (map node-package
+   (filter-map node-package
        (topological-sort (list (lookup-node package-name version))
--8<---------------cut here---------------end--------------->8---

...which also works for other importers which return (values #f ...):

--8<---------------cut here---------------start------------->8---
~/guix$ for importer in stackage elpa gem cran go ;  do printf "\n### $importer\n" ;  ./pre-inst-env guix import $importer really-does-not-exist -r ;done

### stackage
guix import: error: really-does-not-exist: Stackage package not found

### elpa
guix import: error: couldn't find meta-data for ELPA package `really-does-not-exist'.

### gem

### cran
error: failed to retrieve package information from "https://cran.r-project.org/web/packages/really-does-not-exist/DESCRIPTION": 404 ("Not Found")
guix import: error: couldn't find meta-data for R package

### go
guix import: warning: Failed to import package "really-does-not-exist".
reason: "https://proxy.golang.org/really-does-not-exist/@v/list" could not be fetched: HTTP error 410 ("Gone").
This package and its dependencies won't be imported.
--8<---------------cut here---------------end--------------->8---

> Well, it is not worse for most of the importers.  And perhaps this patch
> is worth.  As explained in [1], all the recursive importers should be
> unified and the errors correctly handled, IMHO.  With jeko, we are
> pair-programming to work on it... but we are really slow. ;-)

Yes, this is very much just a stopgap. In your words (from #45984):

> Well, this patch set are trivial changes that quickly fix the current
> broken situation without a deep revamp.

I will follow up with an updated patch.

Regards,
Sarah