Re: [REQUEST] Infinite recursion warning

[Akim Demaille]

Le 10 déc. 2013 à 02:01, Valentin Tolmer <address@hidden> a écrit :

> Hello,
> 
> In the following grammar, the only word recognized is NIL, because of
> an infinite recursion.
> 
> exp:
> NIL
> | NIL list
> 
> list:
> NIL list
> 
> It would be nice if Bison could raise a warning in case of an infinite
> recursion.

Hi Valentin,

I suppose you mean that the message should be clearer?

$ cat foo.yy
%%
exp: "NIL" | "NIL" list
list: "NIL" list
$ LC_ALL=C bison foo.yy
foo.yy: warning: 1 nonterminal useless in grammar [-Wother]
foo.yy: warning: 2 rules useless in grammar [-Wother]
foo.yy:2.20-23: warning: nonterminal useless in grammar: list [-Wother]
 exp: "NIL" | "NIL" list
                    ^^^^
foo.yy:2.14-23: warning: rule useless in grammar [-Wother]
 exp: "NIL" | "NIL" list
              ^^^^^^^^^^
foo.yy:3.7-16: warning: rule useless in grammar [-Wother]
 list: "NIL" list
       ^^^^^^^^^^