Fix spans on %empty

Author: ratmice

cfgrammar/src/lib/yacc/parser.rs

@@ -848,9 +848,8 @@ impl YaccParser {
                 if !(self.lookahead_is("|", i).is_some() || self.lookahead_is(";", i).is_some()) {
                     return Err(self.mk_error(YaccGrammarErrorKind::ProductionNotTerminated, i));
                 }
-            } else if let Some(mut j) = self.lookahead_is("%empty", i) {
+            } else if let Some(j) = self.lookahead_is("%empty", i) {
                 let k = self.parse_ws(j, true)?;
-                j = self.parse_ws(j, true)?;
                 // %empty could be followed by all sorts of weird syntax errors: all we try and do
                 // is say "does this production look like it's finished" and trust that the other
                 // errors will be caught by other parts of the parser.
@@ -2839,7 +2838,7 @@ B";
 Expr: %empty | Factor;
 Factor: ')' Expr ')';
 ",
-                (0, Some(Span::new(21, 28))),
+                (0, Some(Span::new(21, 27))),
             ),
             (
                 "%start Expr