Re: How to maintain compatibility with Automake.

[Peter Rosin]

Den 2010-08-10 20:27 skrev Ralf Wildenhues:
> * Ralf Wildenhues wrote on Tue, Aug 10, 2010 at 11:15:21AM CEST:
> > * Gary V. Vaughan wrote on Tue, Aug 10, 2010 at 11:09:33AM CEST:
> > > On 10 Aug 2010, at 15:19, Peter Rosin wrote:
> > > > m4_defun([AM_PROG_AR],
> > > > [AC_CHECK_TOOLS(AR, [ar], false)
> > > > : ${AR=ar}
> > > > AC_SUBST([AR])dnl
> > > > ])# AM_PROG_AR
> > > > ])
> > >
> > > Just like that!
> >
> > NAK.  I don't have time to explain now, but this should be completely
> > unnecessary.  Esp since Libtool already sets $AR.
>
> Sorry for the short and harsh answer, here's a longer explanation:

No problem at all.

> First, LT_INIT already causes AC_CHECK_TOOLS([AR], ...) to be invoked.

Which comes from the _LT_CMD_OLD_ARCHIVE macro, which according to my
original message needed modification, namely to remove that and use
AM_PROG_AR instead. I thought that was obvious, sorry for not spelling
it out...

> Second, overrides of the form
>    m4_ifndef([MACRO],
>    [ AC_DEFUN([MACRO], [...]) ])
>
> in public m4 files (installed in $datarootdir/aclocal) are very
> problematic for third-party projects if MACRO does not come from
> Autoconf itself: aclocal will pick it up and install libtool.m4 in
> projects using MACRO even if the project otherwise doesn't use Libtool
> at all!  Users were quite annoyed about that.
>
> Now, in the above you don't use AC_DEFUN, so hopefully that particular
> aclocal issue is lessened.  But still, I have had too much pain with
> additions to lt~obsolete.m4[1] that I'd really prefer not adding macros
> which belong to third parties to public Libtool macro files.
>
> For macros that are otherwise present only in the Autoconf project, this
> issue is not a problem: there is not an ordering problem between files
> in $datarootdir/autoconf and $datarootdir/aclocal.  That's why Gary's
> examples work fine.

I was worried about something like that and it was quite deliberate to
use m4_defun instead of AC_DEFUN, but I don't claim to be a guru so
I'll take your word for it being a bad idea. Just asking...

> Back on topic, I'm writing a reply to
> <http://thread.gmane.org/gmane.comp.gnu.libtool.general/10927/focus=4438>
> that hopefully addresses the remaining questions around AM_PROG_AR.

Great, and big thanks!

Cheers,
Peter