Re: <reductions>

[Joel E. Denny]

On Sun, 28 Oct 2007, Akim Demaille wrote:

> 
> > Can someone explain what was intended by the following code in reduce.c?
> > 
> >   static void
> >   reduce_print (void)
> >   {
> >     if (yacc_flag && nuseless_productions)
> >       fprintf (stderr, ngettext ("%d rule never reduced\n",
> >                                  "%d rules never reduced\n",
> >                                  nuseless_productions),
> >                nuseless_productions);
> > 
> > That is, why does -y cause Bison to report the count of grammatically
> > useless rules as "rules never reduced"?  Later in this function, Bison
> > reports the count again but as "useless rules".  Surely this is wrong, but
> > I'm not sure what was intended.
> 
> I might be wrong, but ISTR that that message
> was forged by Paul to follow POSIX.  At that time
> there was not such emphasis on the fact that there
> were both grammar- and parser- useless rules.

I traced this back to revision 1.1 of reduce.c as committed by RMS on 
12-Jul-94.  Even then, Bison reported the same count twice: once as "rules 
never reduced" and once as "useless rules".  I haven't found anything in 
SUSv3 that discusses this.  Did I miss it?  In revision 1.1 of reduce.c, 
yacc_flag was called fixed_outfiles, but that doesn't make any more sense 
to me.

So, I still don't understand why the above code is needed.  I'm inclined 
to remove it.