Fix when the help message is displayed

Only display the "remove this comma" suggestion when followed by an identifier

Author: lambtowolf

src/libsyntax/parse/parser.rs

@@ -767,8 +767,8 @@ impl<'a> Parser<'a> {
             err.span_label(self.span, format!("expected identifier, found {}", token_descr));
         } else {
             err.span_label(self.span, "expected identifier");
-            if self.token == token::Comma {
-                err.span_suggestion(self.span, "remove this comma", ",".into());
+            if self.token == token::Comma && self.look_ahead(1, |t| *t.is_ident()) {
+                err.span_suggestion(self.span, "remove this comma", "".into());
             }
         }
         err