[parser] Enforce module-specific identifier restriction

src/parsing/preparser.cc

 // Copyright 2011 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.
 
 #include <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 20 matching lines @@
 
 void PreParserTraits::ReportMessageAt(int start_pos, int end_pos,
                                       MessageTemplate::Template message,
                                       const char* arg,
                                       ParseErrorType error_type) {
   pre_parser_->log_->LogMessage(start_pos, end_pos, message, arg, error_type);
 }
 
 
 PreParserIdentifier PreParserTraits::GetSymbol(Scanner* scanner) {
-  if (scanner->current_token() == Token::FUTURE_RESERVED_WORD) {
-    return PreParserIdentifier::FutureReserved();
+  if (scanner->current_token() == Token::ENUM) {
+    return PreParserIdentifier::Enum();
+  } else if (scanner->current_token() == Token::AWAIT) {
+    return PreParserIdentifier::Await();
   } else if (scanner->current_token() ==
              Token::FUTURE_STRICT_RESERVED_WORD) {
     return PreParserIdentifier::FutureStrictReserved();
   } else if (scanner->current_token() == Token::LET) {
     return PreParserIdentifier::Let();
   } else if (scanner->current_token() == Token::STATIC) {
     return PreParserIdentifier::Static();
   } else if (scanner->current_token() == Token::YIELD) {
     return PreParserIdentifier::Yield();
   }
@@ skipping 634 matching lines @@
   ExpressionClassifier classifier(this);
   Expression expr = ParseExpression(true, &classifier, CHECK_OK);
   ValidateExpression(&classifier, CHECK_OK);
 
   // Even if the expression starts with an identifier, it is not necessarily an
   // identifier. For example, "foo + bar" starts with an identifier but is not
   // an identifier.
   if (starts_with_identifier && expr.IsIdentifier() && peek() == Token::COLON) {
     // Expression is a single identifier, and not, e.g., a parenthesized
     // identifier.
-    DCHECK(!expr.AsIdentifier().IsFutureReserved());

[mike3, 2016/02/23 19:29:44]

I'm not convinced that removing this check outright (instead of updating it) is
valid, but I haven't been able to think of a test that proves otherwise.

[adamk, 2016/02/23 22:37:15]

"DCHECK" is the V8 equivalent of "assert": it's not meant to be something that a
known test case could be written for, it's stating assumptions about invariants
at this part of the code. So I'd prefer it be updated rather than removed.

[mike3, 2016/02/24 16:20:54]

Acknowledged.

     DCHECK(is_sloppy(language_mode()) ||
            !IsFutureStrictReserved(expr.AsIdentifier()));
     Consume(Token::COLON);
     Statement statement = ParseStatement(ok);
     return statement.IsJumpStatement() ? Statement::Default() : statement;
     // Preparsing is disabled for extensions (because the extension details
     // aren't passed to lazily compiled functions), so we don't
     // accept "native function" in the preparser.
   }
   // Parsed expression statement.
@@ skipping 574 matching lines @@
     Expect(Token::RBRACE, CHECK_OK);
     return PreParserExpression::Default();
   }
 }
 
 #undef CHECK_OK
 
 
 }  // namespace internal
 }  // namespace v8