Re: [PATCH 7/7] libposix: use git-version-gen for version numbering

[Bruno Haible]

Gary V. Vaughan wrote:
> git-version-gen itself relies on the presence of .git in the
> current directory.  I've made a quick and dirty patch to it
> here to also look in the parent directory... but surely there's
> a nicer way to determine whether the current directory is managed
> by git than this?

A less hacky patch was posted by Giuseppe Scrivano in
  <http://lists.gnu.org/archive/html/bug-gnulib/2010-05/msg00090.html>.
I don't know why that patch was not applied. But I'm not a git expert,
I cannot judge it.

> --- a/libposix/configure.ac
> +++ b/libposix/configure.ac
> @@ -17,6 +22,11 @@ AC_CONFIG_FILES([Makefile lib/Makefile tests/Makefile])
>  AM_INIT_AUTOMAKE([foreign])
>  LT_INIT
>  
> +# libtool interface versioning for libposix.la
> +AC_SUBST([LTV_CURRENT], 0)
> +AC_SUBST([LTV_REVISION], 0)
> +AC_SUBST([LTV_AGE], 0)
> +
>  AC_PROG_CC
>  LIBPOSIX_EARLY
>  AM_PROG_CC_C_O

The libtool interface version IMO does not belong in a configure.ac file.
It can go into Makefile.am, or a separate file.

Rationale: The maintainer is supposed to update these three numbers right
before a release. If it is stored in configure.ac, it takes 10 minutes
to rerun configure and regenerate all Makefiles. This is the thing a maintainer
needs least when he is preparing a release. If it is stored in Makefile.am,
it takes 5 seconds to regenerate that particular Makefile.

For libposix, this may not matter because libposix is likely built in
batch mode normally. But nevertheless it's a bad precedent.

Lesson learned: Don't abuse configure.ac.
+-------------------------------------------------------------------------------+
| - Use configure.ac and autoconf macros for determining platform dependencies. 
|
| - Use Makefile rules (in Makefile.am files) for creating files.               
|
| - Use Makefile.am or a separate file for frequently changing parameters.      
|
+-------------------------------------------------------------------------------+

Bruno