Re: Partial autoconf transition thoughts

["Maciej W. Rozycki" <macro at ds2 dot pg dot gda dot pl>]

On 11 Jun 2003, Alexandre Oliva wrote:

> >  Well, see how AM_INSTALL_LIBBFD is defined. ;-)
> 
> Presumably you're configuring with --enable-shared
> --enable-install-libbfd.  I'd never done that :-)
> 
> Anyway, $(exec_prefix)/$(host_alias) is entirely pointless.
> $(exec_prefix) is already supposed to be host-specific.

 But libbfd is target-specific, so you can't install it directly in
$exec_prefix.  As the result of the discussion I wrote of, the current
approach was selected from two alternatives: 
$exec_prefix/$host_alias/$target_alias/lib and
$exec_prefix/$target_alias/$host_alias/lib.  Of coures neither
$exec_prefix/lib nor $exec_prefix/$target_alias/lib can be used as they
(may) hold other versions of libbfd and $exec_prefix/$host_alias cannot
be, either, as it would work for a single target only. 

> >  Why is that so?  I am looking at what autoconf does right now and I can
> > see that $ac_cv_host_alias is set to $ac_cv_build_alias if $host_alias is
> > empty and $ac_cv_target_alias is set to ac_cv_host_alias if $target_alias
> > is empty.
> 
> Which autoconf are you looking at?

 2.57

> > I hope not for the lone reason of differing between
> > implied and user-specified values
> 
> This was the reason for the behavior change, yes.

 IMHO, it should be stated explicitly, e.g. $host_cross and $target_cross
be set to "yes" if --host and --target are specified by a user,
respectively, otherwise they should be set to "no" and
${build,host,target}_alias should be set to valid system names
unconditionally.  This should simplify the generated output and move the
decision on native vs cross to a single place. 

> >  That's a reasonable approach for now, but why can't autoconf be fixed
> > ultimately? 
> 
> I can't think of any reason for that.  But we're trying to move to
> autoconf 2.57, not some hacked version thereof, so we have to cope
> with its limitations for now.

 OK, so I assume that's more an accident during the transition to the new
setup of 2.5x than a design decision.  Good.

> >  Indeed, but I would prefer to see it done in autoconf so that it need not
> > be repeated locally elsewhere.
> 
> It feels like you're volunteering to convert Nathanael's macros into
> autoconf, do I read it right? :-D :-D

 I would actually do that a bit differetly, more or less as I stated
above, but I would of course look at the Nathanael's macros and reuse to
good bits.  Anyway don't hold your breath -- I lack time these days
desperately.  I'll look at this problem when I can afford.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +