[parser] Enforce module-specific identifier restriction

src/parsing/token.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_TOKEN_H_
 #define V8_PARSING_TOKEN_H_
 
 #include "src/base/logging.h"
 #include "src/globals.h"
 
@@ skipping 128 matching lines @@
   K(TRUE_LITERAL, "true", 0)                                         \
   K(FALSE_LITERAL, "false", 0)                                       \
   T(NUMBER, NULL, 0)                                                 \
   T(SMI, NULL, 0)                                                    \
   T(STRING, NULL, 0)                                                 \
                                                                      \
   /* Identifiers (not keywords or future reserved words). */         \
   T(IDENTIFIER, NULL, 0)                                             \
                                                                      \
   /* Future reserved words (ECMA-262, section 7.6.1.2). */           \
-  T(FUTURE_RESERVED_WORD, NULL, 0)                                   \
   T(FUTURE_STRICT_RESERVED_WORD, NULL, 0)                            \
+  /* `await` is a reserved word in module code only */               \
+  K(AWAIT, "await", 0)                                               \
   K(CLASS, "class", 0)                                               \
   K(CONST, "const", 0)                                               \
+  K(ENUM, "enum", 0)                                                 \
   K(EXPORT, "export", 0)                                             \
   K(EXTENDS, "extends", 0)                                           \
   K(IMPORT, "import", 0)                                             \
   K(LET, "let", 0)                                                   \
   K(STATIC, "static", 0)                                             \
   K(YIELD, "yield", 0)                                               \
   K(SUPER, "super", 0)                                               \
                                                                      \
   /* Illegal token - not able to scan. */                            \
   T(ILLEGAL, "ILLEGAL", 0)                                           \
   T(ESCAPED_KEYWORD, NULL, 0)                                        \
   T(ESCAPED_STRICT_RESERVED_WORD, NULL, 0)                           \
                                                                      \
   /* Scanner-internal use only. */                                   \
   T(WHITESPACE, NULL, 0)                                             \
   T(UNINITIALIZED, NULL, 0)                                          \
                                                                      \
   /* ES6 Template Literals */                                        \
   T(TEMPLATE_SPAN, NULL, 0)                                          \
   T(TEMPLATE_TAIL, NULL, 0)
 
-
 class Token {
  public:
   // All token values.
 #define T(name, string, precedence) name,
   enum Value {
     TOKEN_LIST(T, T)
     NUM_TOKENS
   };
 #undef T
 
   // Returns a string corresponding to the C++ token name
   // (e.g. "LT" for the token LT).
   static const char* Name(Value tok) {
     DCHECK(tok < NUM_TOKENS);  // tok is unsigned
     return name_[tok];
   }
 
   // Predicates
   static bool IsKeyword(Value tok) {
     return token_type[tok] == 'K';
   }
 
   static bool IsIdentifier(Value tok, LanguageMode language_mode,
-                           bool is_generator) {
+                           bool is_generator, bool is_module) {

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

This method is starting to succumb to the boolean trap. I think we could
refactor this method's signature to accept simply accept a token and a Scope
reference, e.g.:

    static bool IsIdentifier(Value tok, Scope* scope)

...but that may violate a separation of concerns principle.

     switch (tok) {
       case IDENTIFIER:
         return true;
       case ESCAPED_STRICT_RESERVED_WORD:
       case FUTURE_STRICT_RESERVED_WORD:
       case LET:
       case STATIC:
         return is_sloppy(language_mode);
       case YIELD:
         return !is_generator && is_sloppy(language_mode);
+      case AWAIT:
+        return !is_module;
       default:
         return false;
     }
     UNREACHABLE();
     return false;
   }
 
   static bool IsAssignmentOp(Value tok) {
     return INIT <= tok && tok <= ASSIGN_MOD;
   }
@@ skipping 112 matching lines @@
   static const char* const name_[NUM_TOKENS];
   static const char* const string_[NUM_TOKENS];
   static const int8_t precedence_[NUM_TOKENS];
   static const char token_type[NUM_TOKENS];
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_TOKEN_H_