ES6: Duplicate properties are no longer an error

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index 8a932582586ed15b6b5b886ccecbe6933ee6d7e1..0c07c325d0308daa1bf570148342ac68ea274a49 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -492,60 +492,6 @@ class ParserBase : public Traits {
       ExpressionT expression,
       Scanner::Location location, const char* message, bool* ok);
 
-  // Used to detect duplicates in object literals. Each of the values
-  // kGetterProperty, kSetterProperty and kValueProperty represents
-  // a type of object literal property. When parsing a property, its
-  // type value is stored in the DuplicateFinder for the property name.
-  // Values are chosen so that having intersection bits means the there is
-  // an incompatibility.
-  // I.e., you can add a getter to a property that already has a setter, since
-  // kGetterProperty and kSetterProperty doesn't intersect, but not if it
-  // already has a getter or a value. Adding the getter to an existing
-  // setter will store the value (kGetterProperty | kSetterProperty), which
-  // is incompatible with adding any further properties.
-  enum PropertyKind {
-    kNone = 0,
-    // Bit patterns representing different object literal property types.
-    kGetterProperty = 1,
-    kSetterProperty = 2,
-    kValueProperty = 7,
-    // Helper constants.
-    kValueFlag = 4
-  };
-
-  // Validation per ECMA 262 - 11.1.5 "Object Initialiser".
-  class ObjectLiteralChecker {
-   public:
-    ObjectLiteralChecker(ParserBase* parser, StrictMode strict_mode)
-        : parser_(parser),
-          finder_(scanner()->unicode_cache()),
-          strict_mode_(strict_mode) { }
-
-    void CheckProperty(Token::Value property, PropertyKind type, bool* ok);
-
-   private:
-    ParserBase* parser() const { return parser_; }
-    Scanner* scanner() const { return parser_->scanner(); }
-
-    // Checks the type of conflict based on values coming from PropertyType.
-    bool HasConflict(PropertyKind type1, PropertyKind type2) {
-      return (type1 & type2) != 0;
-    }
-    bool IsDataDataConflict(PropertyKind type1, PropertyKind type2) {
-      return ((type1 & type2) & kValueFlag) != 0;
-    }
-    bool IsDataAccessorConflict(PropertyKind type1, PropertyKind type2) {
-      return ((type1 ^ type2) & kValueFlag) != 0;
-    }
-    bool IsAccessorAccessorConflict(PropertyKind type1, PropertyKind type2) {
-      return ((type1 | type2) & kValueFlag) == 0;
-    }
-
-    ParserBase* parser_;
-    DuplicateFinder finder_;
-    StrictMode strict_mode_;
-  };
-
   // If true, the next (and immediately following) function literal is
   // preceded by a parenthesis.
   // Heuristically that means that the function will be called immediately,
@@ -1849,8 +1795,6 @@ typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParseObjectLiteral(
   int number_of_boilerplate_properties = 0;
   bool has_function = false;
 
-  ObjectLiteralChecker checker(this, strict_mode());
-
   Expect(Token::LBRACE, CHECK_OK);
 
   while (peek() != Token::RBRACE) {
@@ -1889,9 +1833,6 @@ typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParseObjectLiteral(
             *ok = false;
             return this->EmptyLiteral();
           }
-          // Validate the property.
-          PropertyKind type = is_getter ? kGetterProperty : kSetterProperty;
-          checker.CheckProperty(next, type, CHECK_OK);
           IdentifierT name = this->GetSymbol(scanner_);
           typename Traits::Type::FunctionLiteral value =
               this->ParseFunctionLiteral(
@@ -1955,9 +1896,6 @@ typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParseObjectLiteral(
         }
     }
 
-    // Validate the property
-    checker.CheckProperty(next, kValueProperty, CHECK_OK);
-
     Expect(Token::COLON, CHECK_OK);
     ExpressionT value = this->ParseAssignmentExpression(true, CHECK_OK);
 
@@ -2628,36 +2566,6 @@ ParserBase<Traits>::CheckAndRewriteReferenceExpression(
 #undef CHECK_OK_CUSTOM
 
 
-template <typename Traits>
-void ParserBase<Traits>::ObjectLiteralChecker::CheckProperty(
-    Token::Value property,
-    PropertyKind type,
-    bool* ok) {
-  int old;
-  if (property == Token::NUMBER) {
-    old = scanner()->FindNumber(&finder_, type);
-  } else {
-    old = scanner()->FindSymbol(&finder_, type);
-  }
-  PropertyKind old_type = static_cast<PropertyKind>(old);
-  if (HasConflict(old_type, type)) {
-    if (IsDataDataConflict(old_type, type)) {
-      // Both are data properties.
-      if (strict_mode_ == SLOPPY) return;
-      parser()->ReportMessage("strict_duplicate_property");
-    } else if (IsDataAccessorConflict(old_type, type)) {
-      // Both a data and an accessor property with the same name.
-      parser()->ReportMessage("accessor_data_property");
-    } else {
-      DCHECK(IsAccessorAccessorConflict(old_type, type));
-      // Both accessors of the same type.
-      parser()->ReportMessage("accessor_get_set");
-    }
-    *ok = false;
-  }
-}
-
-
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H