Re: [PATCH] -Werror: fix for rules useless in parser after conflicts.

[George Neuner]

In 
message:  http://lists.gnu.org/archive/html/bison-patches/2010-08/msg00000.html
Joel said:
Besides, bison already supports %error and %error-rr to turn
them into errors.

Those directives are not documented for 2.4.1.  The manual mentions only
"%error-verbose".

George