[es6] early error when Identifier is an escaped reserved word

src/preparser.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_PREPARSER_H
 #define V8_PREPARSER_H
 
 #include "src/bailout-reason.h"
 #include "src/expression-classifier.h"
 #include "src/func-name-inferrer.h"
@@ skipping 666 matching lines @@
                                  ExpressionClassifier* classifier, bool* ok);
 
   ExpressionT ParsePrimaryExpression(ExpressionClassifier* classifier,
                                      bool* ok);
   ExpressionT ParseExpression(bool accept_IN, bool* ok);
   ExpressionT ParseExpression(bool accept_IN, ExpressionClassifier* classifier,
                               bool* ok);
   ExpressionT ParseArrayLiteral(ExpressionClassifier* classifier, bool* ok);
   ExpressionT ParsePropertyName(IdentifierT* name, bool* is_get, bool* is_set,
                                 bool* is_static, bool* is_computed_name,
+                                bool* is_identifier, bool* is_escaped_keyword,
                                 ExpressionClassifier* classifier, bool* ok);
   ExpressionT ParseObjectLiteral(ExpressionClassifier* classifier, bool* ok);
   ObjectLiteralPropertyT ParsePropertyDefinition(
       ObjectLiteralCheckerBase* checker, bool in_class, bool has_extends,
       bool is_static, bool* is_computed_name, bool* has_seen_constructor,
       ExpressionClassifier* classifier, bool* ok);
   typename Traits::Type::ExpressionList ParseArguments(
       Scanner::Location* first_spread_pos, ExpressionClassifier* classifier,
       bool* ok);
   ExpressionT ParseAssignmentExpression(bool accept_IN,
@@ skipping 1312 matching lines @@
       *message = is_strict(language_mode())
                      ? MessageTemplate::kUnexpectedStrictReserved
                      : MessageTemplate::kUnexpectedTokenIdentifier;
       *arg = nullptr;
       break;
     case Token::TEMPLATE_SPAN:
     case Token::TEMPLATE_TAIL:
       *message = MessageTemplate::kUnexpectedTemplateString;
       *arg = nullptr;
       break;
+    case Token::ESCAPED_STRICT_RESERVED_WORD:
+    case Token::ESCAPED_KEYWORD:
+      *message = MessageTemplate::kInvalidEscapedReservedWord;
+      *arg = nullptr;
+      break;
     default:
       const char* name = Token::String(token);
       DCHECK(name != NULL);
       *arg = name;
       break;
   }
 }
 
 
 template <class Traits>
@@ skipping 31 matching lines @@
 
   return result;
 }
 
 
 template <class Traits>
 typename ParserBase<Traits>::IdentifierT
 ParserBase<Traits>::ParseAndClassifyIdentifier(ExpressionClassifier* classifier,
                                                bool* ok) {
   Token::Value next = Next();
+  if (next == Token::ESCAPED_STRICT_RESERVED_WORD) {
+    if (is_strict(language_mode())) {
+      ReportUnexpectedToken(next);
+      *ok = false;
+      return Traits::EmptyIdentifier();
+    }
+    next = Token::IDENTIFIER;
+  }
   if (next == Token::IDENTIFIER) {
     IdentifierT name = this->GetSymbol(scanner());
     // When this function is used to read a formal parameter, we don't always
     // know whether the function is going to be strict or sloppy.  Indeed for
     // arrow functions we don't always know that the identifier we are reading
     // is actually a formal parameter.  Therefore besides the errors that we
     // must detect because we know we're in strict mode, we also record any
     // error that we might make in the future once we know the language mode.
     if (this->IsEval(name)) {
       classifier->RecordStrictModeFormalParameterError(
@@ skipping 74 matching lines @@
   return name;
 }
 
 
 template <class Traits>
 typename ParserBase<Traits>::IdentifierT
 ParserBase<Traits>::ParseIdentifierName(bool* ok) {
   Token::Value next = Next();
   if (next != Token::IDENTIFIER && next != Token::FUTURE_RESERVED_WORD &&
       next != Token::LET && next != Token::STATIC && next != Token::YIELD &&
-      next != Token::FUTURE_STRICT_RESERVED_WORD && !Token::IsKeyword(next)) {
+      next != Token::FUTURE_STRICT_RESERVED_WORD &&
+      next != Token::ESCAPED_KEYWORD &&
+      next != Token::ESCAPED_STRICT_RESERVED_WORD && !Token::IsKeyword(next)) {
     this->ReportUnexpectedToken(next);
     *ok = false;
     return Traits::EmptyIdentifier();
   }
 
   IdentifierT name = this->GetSymbol(scanner());
   if (this->IsArguments(name)) scope_->RecordArgumentsUsage();
   return name;
 }
 
@@ skipping 106 matching lines @@
           scanner()->peek_location(), MessageTemplate::kUnexpectedTokenNumber);
       Next();
       result =
           this->ExpressionFromLiteral(token, beg_pos, scanner(), factory());
       break;
 
     case Token::IDENTIFIER:
     case Token::LET:
     case Token::STATIC:
     case Token::YIELD:
+    case Token::ESCAPED_STRICT_RESERVED_WORD:
     case Token::FUTURE_STRICT_RESERVED_WORD: {
       // Using eval or arguments in this context is OK even in strict mode.
       IdentifierT name = ParseAndClassifyIdentifier(classifier, CHECK_OK);
       result = this->ExpressionFromIdentifier(name, beg_pos, end_pos, scope_,
                                               factory());
       break;
     }
 
     case Token::STRING: {
       classifier->RecordBindingPatternError(
@@ skipping 255 matching lines @@
   // Update the scope information before the pre-parsing bailout.
   int literal_index = function_state_->NextMaterializedLiteralIndex();
 
   return factory()->NewArrayLiteral(values, first_spread_index, literal_index,
                                     is_strong(language_mode()), pos);
 }
 
 
 template <class Traits>
 typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParsePropertyName(
     IdentifierT* name, bool* is_get, bool* is_set, bool* is_static,

[rossberg, 2015/11/06 13:31:05]

There are so many flags now that it's worth turning this into a bitset.

[caitp (gmail), 2015/11/06 16:10:30]

I've started to do this, but it's a pretty substantial change that would bring a
lot of noise into the diff --- will do this in a followup.

-    bool* is_computed_name, ExpressionClassifier* classifier, bool* ok) {
+    bool* is_computed_name, bool* is_identifier, bool* is_escaped_keyword,
+    ExpressionClassifier* classifier, bool* ok) {
   Token::Value token = peek();
   int pos = peek_position();
 
   // For non computed property names we normalize the name a bit:
   //
   //   "12" -> 12
   //   12.3 -> "12.3"
   //   12.30 -> "12.3"
   //   identifier -> "identifier"
   //
@@ skipping 20 matching lines @@
       Consume(Token::LBRACK);
       ExpressionClassifier computed_name_classifier;
       ExpressionT expression =
           ParseAssignmentExpression(true, &computed_name_classifier, CHECK_OK);
       classifier->Accumulate(computed_name_classifier,
                              ExpressionClassifier::ExpressionProductions);
       Expect(Token::RBRACK, CHECK_OK);
       return expression;
     }
 
+    case Token::ESCAPED_KEYWORD:
+      *is_escaped_keyword = true;
+      *is_identifier = true;

[rossberg, 2015/11/06 13:31:04]

Why does an escaped keyword qualify as an identifier? Shouldn't that be mutually
exclusive?

[caitp (gmail), 2015/11/06 16:10:30]

Yeah, I guess --- the thing is, the error is only emit when `is_identifier` is
set right now. I'll just change that to `is_identifier || is_escaped_keyword` or
something, I guess

+      *name = ParseIdentifierNameOrGetOrSet(is_get, is_set, CHECK_OK);
+      break;
+
     case Token::STATIC:
       *is_static = true;
 
     // Fall through.
     default:
+      *is_identifier = true;
       *name = ParseIdentifierNameOrGetOrSet(is_get, is_set, CHECK_OK);
       break;
   }
 
   uint32_t index;
   return this->IsArrayIndex(*name, &index)
              ? factory()->NewNumberLiteral(index, pos)
              : factory()->NewStringLiteral(*name, pos);
 }
 
 
 template <class Traits>
 typename ParserBase<Traits>::ObjectLiteralPropertyT
 ParserBase<Traits>::ParsePropertyDefinition(
     ObjectLiteralCheckerBase* checker, bool in_class, bool has_extends,
     bool is_static, bool* is_computed_name, bool* has_seen_constructor,
     ExpressionClassifier* classifier, bool* ok) {
   DCHECK(!in_class || is_static || has_seen_constructor != nullptr);
   ExpressionT value = this->EmptyExpression();
   IdentifierT name = this->EmptyIdentifier();
   bool is_get = false;
   bool is_set = false;
   bool name_is_static = false;
   bool is_generator = Check(Token::MUL);
 
   Token::Value name_token = peek();
   int next_beg_pos = scanner()->peek_location().beg_pos;
   int next_end_pos = scanner()->peek_location().end_pos;
+  bool is_identifier = false;
+  bool is_escaped_keyword = false;
   ExpressionT name_expression = ParsePropertyName(
-      &name, &is_get, &is_set, &name_is_static, is_computed_name, classifier,
+      &name, &is_get, &is_set, &name_is_static, is_computed_name,
+      &is_identifier, &is_escaped_keyword, classifier,
       CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
 
   if (fni_ != nullptr && !*is_computed_name) {
     this->PushLiteralName(fni_, name);
   }
 
   if (!in_class && !is_generator) {
     DCHECK(!is_static);
 
     if (peek() == Token::COLON) {
       // PropertyDefinition
       //    PropertyName ':' AssignmentExpression
       if (!*is_computed_name) {
         checker->CheckProperty(name_token, kValueProperty, false, false,
                                CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
       }
       Consume(Token::COLON);
       value = this->ParseAssignmentExpression(
           true, classifier, CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
       return factory()->NewObjectLiteralProperty(name_expression, value, false,
                                                  *is_computed_name);
     }
 
-    if (Token::IsIdentifier(name_token, language_mode(),
-                            this->is_generator()) &&
-        (peek() == Token::COMMA || peek() == Token::RBRACE ||
-         peek() == Token::ASSIGN)) {
+    if (is_identifier && (peek() == Token::COMMA || peek() == Token::RBRACE ||
+                          peek() == Token::ASSIGN)) {
       // PropertyDefinition
       //    IdentifierReference
       //    CoverInitializedName
       //
       // CoverInitializedName
       //    IdentifierReference Initializer?
+      if (!Token::IsIdentifier(name_token, language_mode(),
+                               this->is_generator())) {
+        ReportUnexpectedTokenAt(scanner()->location(), name_token);
+        *ok = false;
+        return this->EmptyObjectLiteralProperty();
+      }
+      if (is_escaped_keyword) {

[rossberg, 2015/11/06 13:31:05]

See above, I'm confused, which case would this cover?

[caitp (gmail), 2015/11/06 19:08:06]

originally, I had wanted to report a slightly different message --- but then I
thought there wasn't much point, so this is dead code now. removed in the next
patch set

+        classifier->RecordExpressionError(

[rossberg, 2015/11/06 13:31:05]

Wouldn't this be an error unconditionally? In which contexts wouldn't it be?

[caitp (gmail), 2015/11/06 19:08:06]

it always is, the original idea was just to use a different error message ---
but at some point I dropped that idea and never removed this. It's gone now

+            scanner()->location(),
+            MessageTemplate::kInvalidEscapedReservedWord);
+        classifier->RecordBindingPatternError(
+            scanner()->location(),
+            MessageTemplate::kInvalidEscapedReservedWord);
+      }
       if (classifier->duplicate_finder() != nullptr &&
           scanner()->FindSymbol(classifier->duplicate_finder(), 1) != 0) {
         classifier->RecordDuplicateFormalParameterError(scanner()->location());
       }
       if (name_token == Token::LET) {
         classifier->RecordLetPatternError(
             scanner()->location(), MessageTemplate::kLetInLexicalBinding);
       }
 
       ExpressionT lhs = this->ExpressionFromIdentifier(
@@ skipping 61 matching lines @@
 
   if (is_get || is_set) {
     // MethodDefinition (Accessors)
     //    get PropertyName '(' ')' '{' FunctionBody '}'
     //    set PropertyName '(' PropertySetParameterList ')' '{' FunctionBody '}'
     name = this->EmptyIdentifier();
     bool dont_care = false;
     name_token = peek();
 
     name_expression = ParsePropertyName(
-        &name, &dont_care, &dont_care, &dont_care, is_computed_name, classifier,
-        CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
+        &name, &dont_care, &dont_care, &dont_care, is_computed_name, &dont_care,
+        &dont_care, classifier, CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
 
     if (!*is_computed_name) {
       checker->CheckProperty(name_token, kAccessorProperty, is_static,
                              is_generator,
                              CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
     }
 
     FunctionKind kind = FunctionKind::kAccessorFunction;
     if (!in_class) kind = WithObjectLiteralBit(kind);
     typename Traits::Type::FunctionLiteral value = this->ParseFunctionLiteral(
@@ skipping 1452 matching lines @@
       return;
     }
     has_seen_constructor_ = true;
     return;
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PREPARSER_H