Subject: [bug#74481] [PATCH 1/2] git: Catch Git errors when updating cached checkout.

From: Simon Tournier <[email-masked]>
Date: Tue, 17 Dec 2024 19:06:14 +0100

Hi Ludo,

On Tue, 17 Dec 2024 at 11:55, Ludovic Courtès <[email-masked]> wrote:

> We have something that can now return #f instead of throwing an
> exception.  The many users of this interface are not prepared for this;
> worse, getting #f instead of an exception means we lose information as
> to why ‘update-cached-checkout’ or similar failed.

Thanks for explaining.

Well, I’d say “mouais“ :-) about « lose information » since I added some
’pk’ here or there before finding the relevant piece of code.  So the
exception is not very helpful, not to say fully useless, IMHO.

That’s said, I understand your concern and I will not discuss it
here. :-) If I read you correctly and apply the argument, you propose to
guard all the calls of ’update-cached-checkout’, it means:

--8<---------------cut here---------------start------------->8---
./guix/import/egg.scm:94:                  (directory commit _ (update-cached-checkout url)))
./guix/scripts/system/reconfigure.scm:355: (update-cached-checkout
./guix/git.scm:670:                        (update-cached-checkout url
./guix/inferior.scm:877:                   (update-cached-checkout (channel-url channel)
--8<---------------cut here---------------end--------------->8---

Either using ‘(catch 'git-error’ or either using
‘(with-git-error-handling’.

Right?

> Would it be an option to catch 'git-error around the
> ‘update-cached-checkout’ call in (guix import go)?  If an exception is
> thrown, it would print a warning and return a fake hash.

See v2 for this case of ‘guix import go’.

Cheers,
simon

PS: As I said earlier, I think all the call to Guile-Git should be
guarded and each call should manage the exception instead of propagate
it… and so barely catch them. :-)