Darcs-Git: upgrading to Git 0.99

[Juliusz Chroboczek <Juliusz.Chroboczek@pps.jussieu.fr>]

[CC'd to the Git mailling list; please CC any replies to Darcs-Devel]

David, Ian,

I'd like to upgrade the Git code used in Darcs to 0.99 (we're
currently using 0.6).  There are two good reasons for that, the first
of which is actually a showstopper:

 - the format of Git repositories has changed incompatibly, with a new
   kind of thing called the ``pack'' (a very neat performance hack, by
   the way); hence, Darcs-Git is unable to read recent Git repos,
   unless you use the Git tools to unpack them;

 - 0.99 actually exports usable interfaces, which will allow us to use
   pristine Git sources in Darcs.

Now I'm wondering how to do that.  Currently, I'm using a nasty hack
using the C preprocessor to include just the sources we need in
Darcs.  As 0.99 builds a ``libgit.a'', I'd like to use that instead.

There are three ways to do that:

  (1) require that the users put a suitable libgit.a in /usr/local/lib
      before building Darcs, and distribute a tarball of Git from
      darcs.net;

  (2) include just the sources needed for libgit.a in Darcs, and have
      the Darcs build build a local libgit

  (3) as (2), but include all of Git, including their
      ``user-friendly'' scripts.

Solution (2) will include 33 files totalling 167KB, while (3) is about
a megabyte of source.

My personal favourite is solution (2), as it is simple for both the
users and us.  I'm not very keen on (1), as it will cause problems
when the friendly Git folks change their interfaces, but have no
strong dislike towards it if it's what you think is right.  (3) is
definitely overkill.

                                        Juliusz