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Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks
From: |
Nick Bowler |
Subject: |
Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks |
Date: |
Mon, 12 Nov 2012 17:41:29 -0500 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On 2012-11-12 15:19 -0700, Eric Blake wrote:
> On 11/12/2012 03:13 PM, Nick Bowler wrote:
> >> If libtool will get the information in a different way, then that new
> >> way must return the same information - and that implies that autoconf
> >> now has to do something with AC_CONFIG_MACRO_DIR.
> >
> > On this point, I disagree: the way to maintain compatibility is to not
> > change this macro, and instead add a totally new one (which we've done:
> > it's called AC_CONFIG_MACRO_DIRS with an S) that new packages can make
> > use of if they want, and old packages can continue to not use.
> >
> > I thought my examples already demonstrated where the proposed changes
> > would cause existing, *working* configure.ac files to fail after
> > updating to a version of Autoconf with the changes.
>
> Our point is that any configure.ac with two or more AC_CONFIG_MACRO_DIR
> is NOT working. It was merely lucky that it wasn't tripping over other
> problems.
After 10 years of consistency, it stops being mere luck and starts being
expected behaviour. Especially since, as mentioned earlier, nobody ever
documented what AC_CONFIG_MACRO_DIR actually was supposed to do. So the
only thing users have ever had to go on was the behaviour of their
tools.
> But since we can't make it continue to work with the new
> semantics of AC_CONFIG_MACRO_DIRS, the best we can do (and indeed, what
> we DID do) is loudly flag incorrect usage as an error rather than
> silently change semantics.
Sorry, I don't understand. You seem to be claiming that the addition of
AC_CONFIG_MACRO_DIRS (an entirely new macro, with documented behaviour)
to Autoconf will somehow break the following pattern if we don't also
change the definition of AC_CONFIG_MACRO_DIR?
configure.ac:
AC_CONFIG_MACRO_DIR([foo])
Makefile.am:
ACLOCAL_AMFLAGS = -I foo
What breaks? How does it break? Why will this not continue to work
exactly as it has in the past if we do not keep AC_CONFIG_MACRO_DIR's
definition exactly as it is right now, i.e.:
AC_DEFUN([AC_CONFIG_MACRO_DIR], [])
?
> > The backwards-compatible way of handing AC_CONFIG_MACRO_DIR is to have
> > it do exactly what it has done for the past 10 years: nothing useful.
>
> When used exactly once, it does just that.
Another thing to consider is that, if you aren't using libtool, the
following will work fine today, too (and I think will be totally broken
by this change):
configure.ac:
AC_CONFIG_MACRO_DIR([somewhere-else])
Makefile.am:
ACLOCAL_AMFLAGS = -I m4
Cheers,
--
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
- [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/09
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/09
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Adrian Bunk, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks,
Nick Bowler <=
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/13
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Adrian Bunk, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/12
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/13
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Adrian Bunk, 2012/11/13
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/13
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Stefano Lattarini, 2012/11/13
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Eric Blake, 2012/11/13
- Re: [PATCH] AC_CONFIG_MACRO_DIRS: improve tracing and add sanity checks, Nick Bowler, 2012/11/13