Re: questions about AC_CONFIG_MACRO_DIR

[Ralf Wildenhues]

Hello Stefan,

* Stefan Seefeld wrote on Tue, Sep 12, 2006 at 04:50:40PM CEST:
> I have just read about AC_CONFIG_MACRO_DIR as a means to
> specify additional places to look for M4 macros.
> 
> I notice that the generated configure script still
> contains traces of that macro, notably, a check for
> the directory that was given as argument.
> 
> What is the purpose of this ? Since macro lookup
> and expansion happens during calls to aclocal, autoconf,
> etc., there shouldn't be any need for the generated
> configure script to care, or should it ?

The idea is that your final package tarball should contain what's
needed to recreate the generated configure script.

Traditionally, aclocal has been employed to this end: all macros not
provided by Autoconf itself, or by the package author in acinclude.m4,
are put into aclocal.m4.  But this was deemed cumbersome: it's not easy
to update some of the macros in aclocal.m4, for example.  So newer
Automake have the mechanism that if you have additional .m4 files in
your source tree that you let aclocal include (for example, by issuing
  aclocal -I m4

or equivalently for autoreconf, adding a line `ACLOCAL_AMFLAGS -I m4' to 
Makefile.am), then aclocal will not copy those macros verbatim into the
file aclocal.m4, but instead add a line
  m4_include([m4/macro-file.m4])

to it.  Much nicer: you can have third-party tools such as libtoolize
update a file like m4/libtool.m4 instead of having a huge aclocal.m4
macro with all of libtool.m4 in it somewhere.

The aclocal from Automake-1.9b works this way, in that you can instruct
aclocal to install macro files (from, say /usr/share/aclocal-x.y) into
the directory named by AC_CONFIG_MACRO_DIR, and the libtoolize from CVS
Libtool recognizes the AC_CONFIG_MACRO_DIR as well and puts its macro
files there.

(I apologize that my description is somewhat incomplete and informal,
as I don't have the exact semantics memorized; hopefully someone will
correct any obvious mistakes.)

> (The reason I'm asking is that, while the machine where
> I run autoconf does have said directory, but the machine
> where I actually configure and build the package doesn't,
> and so configure bails out.)

What's the reason for
- specifying AC_CONFIG_MACRO_DIR, but
- not shipping the macros in the tarball?

Cheers,
Ralf