Re: [PATCH 1/2] AC_CONFIG_MACRO_DIRS: new macro, mostly for aclocal

[Eric Blake]

On 10/17/2012 01:49 AM, Gary V. Vaughan wrote:
> Hi Nick,
> 
> On Oct 17, 2012, at 3:46 AM, Nick Bowler <address@hidden> wrote:
>> Tools like libtoolize will (again, hopefully) be using this information
>> to decide where to copy libtool macros.  Probably aclocal --install will
>> need to do this as well.  If multiple macro directories are specified,
>> which one should they use?  I think the answer should be: "The first
>> directory in the documented ordering", if for no other reason than that
>> is what libtoolize currently does when it snarfs in ACLOCAL_AMFLAGS.
> 
> For a few years now, libtoolize has checked that the first -I <dirname> 
> matches
> the argument to AC_CONFIG_MACRO_DIR, when both are given, providing
> a diagnostic error if they do not. Otherwise if only one of those is provided 
> by
> the calling project, it uses whichever is provided as the destination for
> libtool.m4 and friends.

But the point of this patch is that automake will be dropping
ACLOCAL_AMFLAGS, and thus AC_CONFIG_MACRO_DIR should be the canonical
point at which aclocal looks.  Furthermore, since both you and I have
already pointed out that if AC_CONFIG_MACRO_DIR is given more than once,
libtool checks the _last_ occurrence, but you also stated that libtool
matches this against the _first_ -I<dirname> in ACLOCAL_AMFLAGS, we have
a discrepancy problem in libtool.  Autoconf releases should not be bound
by libtool release schedules, so the solution is a new macro,
AC_CONFIG_MACRO_DIRS, for anyone that wants to list more than one
directory, leaving a lone use of AC_CONFIG_MACRO_DIR to satisfy older
libtool.

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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