Re: [PATCH 07/12] use a shell function for AC_CHECK_HEADER

[Eric Blake]

Ralf Wildenhues <Ralf.Wildenhues <at> gmx.de> writes:

> > > It looks to me like overall, the shell function changes will make user
> > > code even more reliant on correct M4 quotation than before.
> > 
> > Why?
> 
> Because the changes introduce more elaborate M4 constructions overall,
> relying more on correct user-side quoting than was needed before.
> At least that's my impression, I do not have hard data for this.

I think we've tried to keep the AC_ API unchanged.  AS_CASE is actually more 
tolerant to bad quoting than it used to be.  But yes, I concede that bad m4 
quoting may bite people where they used to get away with it, due to so many 
changes in implementation.

> 
> Don't get me wrong, I'm not trying to criticize.  The move to shell
> function is worth much more than trying to forever support broken
> user scripts.  However, it should be very clear that the next Autoconf
> release quite necessarily is a less stable one for users than the last
> one, even if it all it causes is to uncover some more latent issues
> in user's configure.ac and .m4 macro files.  Long-term, that can only
> be a good thing.

I'm planning on doing a beta release once we go a week or two without too much 
churn.  Perhaps even calling it Autoconf 2.90 (in preparation for a stable 3.0) 
rather than 2.64, since we have made so many radical changes in implementation.

> 
> >  Anyway, shell functions will have to be mentioned in NEWS.

They are.

-- 
Eric Blake