hard dependency on Git? (was bug#65866: [PATCH 0/8] Add built-in builder for Git checkouts)

[Simon Tournier]

Hi,

On Mon, 11 Sep 2023 at 16:23, Ludovic Courtès <ludo@gnu.org> wrote:

> Note that the patch series adds a hard dependency on Git.
> This is because the existing ‘git-fetch’ code depends on Git,
> which is itself motivated by the fact that Git supports
> shallow clones and libgit2/Guile-Git doesn’t.

Going this path, I appears to me worth to revisit the proposal:

        RFC: libgit2 is slow/inefficient; switch to git command?
        Maxim Cournoyer <maxim.cournoyer@gmail.com>
        Mon, 21 Nov 2022 21:21:02 -0500
        id:87cz9fpw4x.fsf@gmail.com
        https://yhetil.org/guix/87cz9fpw4x.fsf@gmail.com
        https://lists.gnu.org/archive/html/guix-devel/2022-11

I know it is not an option for now to parse the output of ’git’ commands
in order to keep the features of (guix git), (guix channels), etc.

However, this discussion was mentioning an implementation of
clone/checkout in pure Racket supporting shallow checkout.  Considering
the current level of integration, I thought the next Big Plan™ was to
gradually move bits of Guile-Git to being pure Scheme, maybe based on
the Racket implementation of ’clone’ as a starting point.

Personally, I do not have a strong opinion about the Big Plan™.  I note
that the introduction of Git as a hard dependency is a slippery slope
considering the current state of libgit2.  Here, it starts with “git
clone”, then “git gc” (unsupported by libgit2) is also in the pipes
(#65720 [1]).  And after timing, I am almost sure that many operations
using Guile-Git will be slower than their plain Git counter-parts.  And
we will start to parse the output of ’git’ plumbing commands.  Slippery
slope for pushing Guile-Git out, no?

And I do not speak about the closure.  Is it possible to extract the
command ’git-clone’ from git-minimal?  It would reduce the size, no?


Cheers,
simon

1: https://issues.guix.gnu.org/65720