Re: warning: unused value: $3

[henrik . sorensen]

On Thursday 26 October 2006 22:55, Joel E. Denny wrote:
> On Thu, 26 Oct 2006 address@hidden wrote:
> > > That is, do you believe this warning is too much trouble to be
> > > worthwhile?
> >
> > The warning would be ok, if it was only true.
>
> It's true inasmuch as we specifically intended to warn about the current
> rule's actions without regard to other rules.  Perhaps that would be clear
> if the message were reworded.
even if you reword it, it will still be missleading.

>
> > > Surely it's useful in many cases, but could something be
> > > changed about it to accommodate the troublesome cases?  Or is it ok as
> > > is?
> >
> > the best thing would to detect that the $3 in rule procoptionlist is
> > referenced as $0 in procoption
>
> In general, that seems difficult to compute because $0 or $-n could appear
yes, the general problem is probably impossible
> in semantic actions at any level in the parse tree.  Bison would have to
> check every possible expansion of every possible RHS symbol.  That
> implementation seems like more work than I want to do.
... but how hard would it be to check just one level ?
>
> What if we simply add an option to turn this warning off globally?
I think that for my development, I will just do a dummy reference to $3

Henrik