Re: warn-on-use.m4 requires modern M4?

[Eric Blake]

Simon Josefsson <simon <at> josefsson.org> writes:

> I get errors from autoreconf when bootstrapping Libidn on a Ubuntu 8.04
> LTS system, and removing the recent warn-on-use.m4 file fixes it.  Is
> there something in the file that requires a recent GNU M4?  Ubuntu 8.04
> has GNU M4 1.1.10, and according to gnulib's DEPENDENCIES 1.4.5 or later
> should be OK.

m4 1.4.6 or better is preferred (and in fact, enforced by newer autoconf), but 
yes, 1.4.5 is okay with older autoconf.

The problem is not old m4, but old autoconf.  Which version are you using?

Meanwhile, I can work around the problem by making sure warn-on-use.m4 defines 
enough helper macros if they are not already defined by autoconf.  I just need 
to know which helper macros weren't available.  We already guarantee 
m4_foreach_w in gnulib-common.m4, so I'm guessing that it might be AS_VAR_IF or 
AS_VAR_SET.

<time passes>

Sure enough, we have other uses of AS_VAR_SET in gnulib, but I appear to be the 
first user of AS_VAR_IF (well, warnings.m4 uses gl_AS_VAR_IF); that macro was 
only introduced in autoconf 2.63b, even though gnulib still claims to work with 
as old as 2.59.

So, the right patch would be to move gl_AS_VAR_IF out of warnings.m4, and make 
gnulib-common.m4 define a fallback AS_VAR_IF.  I'll take care of that.

Meanwhile, based on the recent security hole in older automake, should we bite 
the bullet and require automake 1.10.3 or better (which in turn bumps the 
minimum autoconf requirement from 2.59 up to 2.60)?

-- 
Eric Blake