bug#7773: (lack of) config.h description in manual

[Ralf Wildenhues]

Hi Karl,

* Karl Berry wrote on Mon, Jan 03, 2011 at 01:17:00AM CET:
> Following up to my own mail,

No.  :-)  This opened a new bug report.  I'm closing it, for reasons
explained below.

> it seems I have been missing something
> basic all these years, since it's never come up in my own packages: in
> order to use the directory variables like $(LIBDIR) in the code, it
> seems each package has to hack them in to config.h, e.g., via gnulib's
> "configmake" module.  Right?

Well, the configmake module is an application of the technique described
in
  info Autoconf "Defining Directories"

> This is surprising.  A programmer coming to the autotools would hardly
> expect to have to write their own glue script merely to get access to
> the standard directories in the code.

All discussed in above node.

> I strongly suggest explicitly discussing this in the manual.  Maybe even
> showing an example of how to do it,

All done above.  No, I do not think that automake.info should repeat all
of autoconf.info information.

> or at least referring to gnulib's configmake.

Feel free to send a patch to autoconf-patches to amend that (or just
write there, and one of us will get to it).  Thanks.

> (It'd be even better IMHO to just make them standardly available in
> config.h somehow, e.g., as #define AM_LIBDIR and the like, but I can't
> wrap my mind around a real spec, sorry ...)

That does not work, and the above node explains why: the GNU Coding
Standards forbid it, implicitly.

Cheers,
Ralf