Visitor to turn generic productions into void productions. Note
that this visitor also voids productions that have
xtc.tree.Node or
xtc.tree.GNode as their types.
This visitor assumes that the entire grammar is contained in a
single module.
author: Robert Grimm version: $Revision: 1.11 $
Check the specified binding or string match. If the bound or
matched element has been voided by this visitor, this method
reports an error. However, bindings to yyValue in voided
productions are eliminated.
Parameters: op - The binding or string match. The checked element.