[parser] implement error reporting for Scanner errors

src/parsing/parser-base.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
 #include "src/hashmap.h"
@@ skipping 994 matching lines @@
 void ParserBase<Traits>::ReportUnexpectedToken(Token::Value token) {
   return ReportUnexpectedTokenAt(scanner_->location(), token);
 }
 
 
 template <class Traits>
 void ParserBase<Traits>::ReportUnexpectedTokenAt(
     Scanner::Location source_location, Token::Value token,
     MessageTemplate::Template message) {
   const char* arg;
+  if (token == Token::ILLEGAL && scanner()->has_error()) {

[adamk, 2016/03/18 18:21:55]

Can you put this logic inside GetUnexpectedToken instead? That'll require adding
a Scanner::Location* arg, but that seems fine.

[caitp (gmail), 2016/03/21 16:15:03]

Done.

+    Traits::ReportMessageAt(scanner()->error_location(), scanner()->error());
+    return;
+  }
   GetUnexpectedTokenMessage(token, &message, &arg);
   Traits::ReportMessageAt(source_location, message, arg);
 }
 
 
 template <class Traits>
 typename ParserBase<Traits>::IdentifierT ParserBase<Traits>::ParseIdentifier(
     AllowRestrictedIdentifiers allow_restricted_identifiers, bool* ok) {
   ExpressionClassifier classifier(this);
   auto result = ParseAndClassifyIdentifier(&classifier, ok);
@@ skipping 2062 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H