Toplevel configure.ac / Makefile.am for optional directories

[J.T. Conklin]

I've been working on the Automake build infrastructure for the ACE and
TAO libraries.

TAO depends on and is packaged with ACE, but ACE is also available in
a standalone distribution.

My attempt to handle this was a conditional subdirectory in the
toplevel Makefile.am like:

         if BUILD_TAO
         SUBDIRS += TAO
         endif

and this code in the toplevel configure.ac:

         if test -d $srcdir/TAO; then
            AC_CONFIG_SUBDIRS([TAO])
         fi
         AM_CONDITIONAL([BUILD_TAO], [test -d $srcdir/TAO])

I thought this was working fine, but then again I've never actually
tried it with an ACE-only distribution.  One of the other ACE/TAO 
contributors did and found that autoreconf failed with:

    $ autoreconf --install --force
    Putting files in AC_CONFIG_AUX_DIR, `aux_config'.
    Makefile.am:34: required directory ./TAO does not exist
    autoreconf: failed to run automake: No such file or directory

Any suggestions?

    --jtc

-- 
J.T. Conklin