Re: [PATCH] Enable use of older two part flavor 'git describe'.

[Jim Meyering]

FYI, I've just pushed the following patch.
Bob found that it is required to work around a relatively obscure
problem you'd see only when trying to bootstrap the autotools tool chain
with only the relatively old git-1.4.4.4 installed (debian unstable).
The problem was that your built-from-sources autoconf would end up with
a version string like 2.61a-ab8fd, which is not of the usual M.N.O-hhhhhh form.
That difference is due to the way older "git describe" works.
It doesn't include the commit-number.

That would then cause trouble with m4's configure.ac, which does this:

  AC_PREREQ([2.61a.347])

So Bob fixed git-version-gen to do the right thing,
even with older versions of git.

Here's this patch:

address@hidden (Bob Proulx) wrote:
> Jim,
>
> This appears to allow git-version-gen to handle either the old or the
> new git describe format.  Using this in gnulib allows m4 to build
> using the latest autoconf which was checked out using the older git.
>
> Bob
>
>
> diff --git a/ChangeLog b/ChangeLog
> index 1c052ac..b5e537d 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,10 @@
> +2008-02-20  Bob Proulx  <address@hidden>
> +
> +     Enable use of older two part flavor 'git describe'.
> +     * build-aux/git-version-gen: If using the older two part flavor of
> +     git version then recreate the third part now present in the
> +     newer three part flavor of git describe.
> +
>  2008-02-20  Martin Buchholz  <address@hidden>  (tiny change)
>
>       * lib/fts.c (fts_build): Typo correction to comment.
> diff --git a/build-aux/git-version-gen b/build-aux/git-version-gen
> index 1d58adc..1a00107 100755
> --- a/build-aux/git-version-gen
> +++ b/build-aux/git-version-gen
> @@ -59,6 +59,23 @@ elif test -d .git \
>        *) (exit 1) ;;
>         esac
>  then
> +    # Is this a new git that lists number of commits since the last
> +    # tag or the previous older version that did not?
> +    #   Newer: v6.10-77-g0f8faeb
> +    #   Older: v6.10-g0f8faeb
> +    case $v in
> +     *-*-*) : git describe is okay three part flavor ;;
> +     *-*)
> +         : git describe is older two part flavor
> +         # Recreate the number of commits and rewrite such that the
> +         # result is the same as if we were using the newer version
> +         # of git describe.
> +         vtag=`echo "$v" | sed 's/-.*//'`
> +         numcommits=`git rev-list "$vtag"..HEAD | wc -l`
> +         v=`echo "$v" | sed "s/\(.*\)-\(.*\)/\1-$numcommits-\2/"`;
> +         ;;
> +    esac
> +
>      # Change the first '-' to a '.', so version-comparing tools work 
> properly.
>      # Remove the "g" in git describe's output string, to save a byte.
>      v=`echo "$v" | sed 's/-/./;s/\(.*\)-g/\1-/'`;