Re: Getting at path to AC_CONFIG_AUX_DIR

[Ralf Wildenhues]

Hello Rhys,

* Rhys Ulerich wrote on Thu, Aug 07, 2008 at 07:55:37PM CEST:
> 
> I'm putting together a (hopefully reusable) macro the requires a script in
> my AC_CONFIG_AUX_DIR directory:
> 
> AC_DEFUN(AC_FOOBARBAZ,[
> #...
> AC_REQUIRE([AC_CONFIG_AUX_DIR_DEFAULT])
> AC_REQUIRE_AUX_FILE([tex-it])
> AC_SUBST(ac_aux_dir)
> # Output a script that will later invoke $(ac_aux_dir)/tex-it during Make
> #...
> ])
> 
> This is a little klunky.  Is there a better way to get of the configured
> AC_CONFIG_AUX_DIR than hijacking ac_aux_dir with AC_SUBST?

That is indeed klunky.  I'm afraid you won't be able to get by without
undocumented Autoconf (or Automake) features at all; but the above is a
bit inconvenient.  First, please AC_SUBST a different variable (which
you initialize from ac_aux_dir), second, without mangling the value is
unusable from subdirectories of the build directory.  Ideally, I guess
Autoconf should provide a public variable that is mangled for each
subdir (like it currently does with $INSTALL, $MKDIR_P).

Automake does
  am_aux_dir=`cd $ac_aux_dir && pwd`

to absolutify its value.  You can do this, but it prevents building from
a source directory with spaces in its name.  (You can't have both, a
possibly relative path but without spaces, and a path that is constant
for all Makefiles.)  This is a bit tricky code (we've gotten previous
instances of similar code wrong repeatedly), and I'm too tired to
venture into it right now.

* Eric wrote:
> > What's wrong with doing this in configure.ac:
> >
> > AC_CONFIG_AUX_DIR([build-aux])
> >
> > then doing this in your Makefile:
> >
> > aux_dir=$(top_srcdir)/build-aux
> > ...
> > rule:
> >        $(SHELL) $(aux_dir)/tex-it

Apart from the other items already discussed, this only runs in the
toplevel Makefile.

> I'm trying to insulate myself  against breakage if/when someone changes the
> build-aux directory name.  It looked like the usual Autoconf missing
> install-sh logic used AC_CONFIG_AUX_DIR_DEFAULT to handle this.  Just
> wondered if there's any public mechanism to handle this.

There should be, eventually.

> Also, generally, how do people package/distribute support scripts (like my
> $(aux_dir)/tex-it) when posting stuff up to the various Autoconf macro
> archives?

This is another problem that should be solved, eventually.  Currently
most other packages either just let the user copy a file, or they have
extra scripts to install such stuff (libtoolize, gettextize,
gnulib-tool, ...), yuck.  automake has --add-missing, maybe one should
just teach it to look for extra files in a standard place.

I'd personally prefer to leave all this stuff to post 2.63.

Cheers,
Ralf