Re: prepare for autoconf-2.60

[Ralf Wildenhues]

* Paul Eggert wrote on Thu, Apr 20, 2006 at 01:50:48AM CEST:
> Bruno Haible <address@hidden> writes:
>
> > + But about AC_CHECK_DECLS_ONCE: note that in
> > + autoconf >= 2.60 the symbol separator is a comma, whereas here it is
> > + whitespace.
> 
> I hadn't noticed this incompatibility.  It is a real hassle.

One solution is to forbid _any_ Gnulib (or other non-Autoconf-provided)
macro to start with `AC_'.  I thought this was a convention agreed upon
long ago (much longer than, say, `build-aux' as a directory name).  Then
one could even write an autoupdate rule to transform gl_CHECK_DECLS_ONCE
into AC_CHECK_DECLS_ONCE and change the white-space separated list into
a M4 list at the same time (with reasonably safe heuristics).[1]

We could scan the argument of Autoconf's AC_CHECK_DECLS_ONCE at M4 time
and warn if we find white space but no comma.  (Similarly Gnulib's
version if we find comma.)

Cheers,
Ralf

[1] You should note that, until recently, autoupdate was really almost
unusable; but a couple of nasty bugs in it have been squatted, and maybe
it's already good enough for many uses now.  :-)