Subject: Re: bug#65352: Fix time-machine and network

From: Ludovic Courtès <[email-masked]>
Date: Mon, 04 Sep 2023 11:32:10 +0200

Hi again,

Simon Tournier <[email-masked]> skribis:

> * guix/git/scm (reference-available?): Rely of the procedure resolve-reference
> to determine if the reference belongs to the local Git checkout.
> ---
>  guix/git.scm | 13 ++-----------
>  1 file changed, 2 insertions(+), 11 deletions(-)
>
> diff --git a/guix/git.scm b/guix/git.scm
> index dbc3b7caa7..ebe2600209 100644
> --- a/guix/git.scm
> +++ b/guix/git.scm
> @@ -360,17 +360,8 @@ (define-syntax-rule (false-if-git-not-found exp)
>  (define (reference-available? repository ref)
>    "Return true if REF, a reference such as '(commit . \"cabba9e\"), is
>  definitely available in REPOSITORY, false otherwise."
> -  (match ref
> -    ((or ('commit . commit)
> -         ('tag-or-commit . (? commit-id? commit)))
> -     (let ((len (string-length commit))
> -           (oid (string->oid commit)))
> -       (false-if-git-not-found
> -        (->bool (if (< len 40)
> -                    (object-lookup-prefix repository oid len OBJ-COMMIT)
> -                    (commit-lookup repository oid))))))
> -    (_
> -     #f)))
> +  (false-if-git-not-found
> +   (->bool (resolve-reference repository ref))))
>  
>  (define (clone-from-swh url tag-or-commit output)
>    "Attempt to clone TAG-OR-COMMIT (a string), which originates from URL, using
>
> base-commit: 1b2d43fe016848ea2ec16ff18cbc14340944fc4e

In fact, now I recall why that procedure was written that way: it’s
meant to say whether a given commit (and only a commit) is already in
the checkout, meaning we don’t need to pull.  By definition, it’s an
answer that can only be given for a specific commit; we cannot tell
whether “master” or “HEAD” is available, that wouldn’t make sense.

Thus, I think we need to revert
a789dd58656d5f7f1b8edf790d77753fc71670af, and probably add a comment
explaining why it’s written this way.

Thoughts?

Ludo’.