[parser] Allow duplicate __proto__ keys in patterns

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/base/hashmap.h"
@@ skipping 891 matching lines @@
       Scanner::Location location, Token::Value token,
       MessageTemplate::Template message = MessageTemplate::kUnexpectedToken);
 
   void ReportClassifierError(
       const typename ExpressionClassifier::Error& error) {
     Traits::ReportMessageAt(error.location, error.message, error.arg,
                             error.type);
   }
 
   void ValidateExpression(const ExpressionClassifier* classifier, bool* ok) {
-    if (!classifier->is_valid_expression() ||
-        classifier->has_cover_initialized_name()) {
-      const Scanner::Location& a = classifier->expression_error().location;
-      const Scanner::Location& b =
-          classifier->cover_initialized_name_error().location;
-      if (a.beg_pos < 0 || (b.beg_pos >= 0 && a.beg_pos > b.beg_pos)) {

[adamk, 2016/08/19 20:17:08]

Ugh, I forgot about this logic, it's trying to determine which error was first.

What if we combined DuplicateProtoProduction with CoverInitializedNameProduction
(not sure what the right name is...)?

Or maybe there should only be a single slot for ExpressionProduction? Would be
interesting to see what tests fail if we combine CoverInitializedName with
Expression in the existing code.

[caitp, 2016/08/19 23:11:19]

IIRC, the reason for this is related to how arrow functions get validated ---
there was some requirement that `({ a = 10 }) =>` be validated as an Expression
before the `=>` gets parsed and processed (this would be in ParseExpression).

That's the only reason for the difference, though.

[gsathya, 2016/08/19 23:22:57]

I combined CoverInitializedName with this for now.

-        ReportClassifierError(classifier->cover_initialized_name_error());
-      } else {
+    if (!classifier->is_valid_expression()) {
         ReportClassifierError(classifier->expression_error());
-      }
+        *ok = false;
+    }
+
+    if (classifier->has_cover_initialized_name()) {
+      ReportClassifierError(classifier->cover_initialized_name_error());
+      *ok = false;
+    }
+
+    if (classifier->has_annexb_duplicate_proto()) {
+      ReportClassifierError(classifier->annexb_duplicate_proto_error());
       *ok = false;
     }
   }
 
   void ValidateFormalParameterInitializer(
       const ExpressionClassifier* classifier, bool* ok) {
     if (!classifier->is_valid_formal_parameter_initializer()) {
       ReportClassifierError(classifier->formal_parameter_initializer_error());
       *ok = false;
     }
@@ skipping 263 matching lines @@
     kAccessorProperty,
     kValueProperty,
     kMethodProperty
   };
 
   class ObjectLiteralCheckerBase {
    public:
     explicit ObjectLiteralCheckerBase(ParserBase* parser) : parser_(parser) {}
 
     virtual void CheckProperty(Token::Value property, PropertyKind type,
-                               MethodKind method_type, bool* ok) = 0;
+                               MethodKind method_type,
+                               ExpressionClassifier* classifier, bool* ok) = 0;
 
     virtual ~ObjectLiteralCheckerBase() {}
 
    protected:
     ParserBase* parser() const { return parser_; }
     Scanner* scanner() const { return parser_->scanner(); }
 
    private:
     ParserBase* parser_;
   };
 
   // Validation per ES6 object literals.
   class ObjectLiteralChecker : public ObjectLiteralCheckerBase {
    public:
     explicit ObjectLiteralChecker(ParserBase* parser)
         : ObjectLiteralCheckerBase(parser), has_seen_proto_(false) {}
 
     void CheckProperty(Token::Value property, PropertyKind type,
-                       MethodKind method_type, bool* ok) override;
+                       MethodKind method_type, ExpressionClassifier* classifier,
+                       bool* ok) override;
 
    private:
     bool IsProto() { return this->scanner()->LiteralMatches("__proto__", 9); }
 
     bool has_seen_proto_;
   };
 
   // Validation per ES6 class literals.
   class ClassLiteralChecker : public ObjectLiteralCheckerBase {
    public:
     explicit ClassLiteralChecker(ParserBase* parser)
         : ObjectLiteralCheckerBase(parser), has_seen_constructor_(false) {}
 
     void CheckProperty(Token::Value property, PropertyKind type,
-                       MethodKind method_type, bool* ok) override;
+                       MethodKind method_type, ExpressionClassifier* classifier,
+                       bool* ok) override;
 
    private:
     bool IsConstructor() {
       return this->scanner()->LiteralMatches("constructor", 11);
     }
     bool IsPrototype() {
       return this->scanner()->LiteralMatches("prototype", 9);
     }
 
     bool has_seen_constructor_;
@@ skipping 723 matching lines @@
     this->PushLiteralName(fni_, *name);
   }
 
   if (!in_class && !is_generator) {
     DCHECK(!IsStaticMethod(method_kind));
     if (peek() == Token::COLON) {
       // PropertyDefinition
       //    PropertyName ':' AssignmentExpression
       if (!*is_computed_name) {
         checker->CheckProperty(name_token, kValueProperty, MethodKind::kNormal,
+                               classifier,
                                CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
       }
       Consume(Token::COLON);
       int beg_pos = peek_position();
       ExpressionT value = this->ParseAssignmentExpression(
           true, classifier, CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
       CheckDestructuringElement(value, classifier, beg_pos,
                                 scanner()->location().end_pos);
 
       return factory()->NewObjectLiteralProperty(name_expression, value,
@@ skipping 80 matching lines @@
         CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
     method_kind |= MethodKind::kAsync;
   }
 
   if (is_generator || peek() == Token::LPAREN) {
     // MethodDefinition
     //    PropertyName '(' StrictFormalParameters ')' '{' FunctionBody '}'
     //    '*' PropertyName '(' StrictFormalParameters ')' '{' FunctionBody '}'
     if (!*is_computed_name) {
       checker->CheckProperty(name_token, kMethodProperty, method_kind,
+                             classifier,
                              CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
     }
 
     FunctionKind kind = is_generator
                             ? FunctionKind::kConciseGeneratorMethod
                             : is_async ? FunctionKind::kAsyncConciseMethod
                                        : FunctionKind::kConciseMethod;
 
     if (in_class && !IsStaticMethod(method_kind) &&
         this->IsConstructor(*name)) {
@@ skipping 30 matching lines @@
     *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));
 
     if (!*is_computed_name) {
       checker->CheckProperty(name_token, kAccessorProperty, method_kind,
+                             classifier,
                              CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
     }
 
     typename Traits::Type::FunctionLiteral value = this->ParseFunctionLiteral(
         *name, scanner()->location(), kSkipFunctionNameCheck,
         is_get ? FunctionKind::kGetterFunction : FunctionKind::kSetterFunction,
         kNoSourcePosition, FunctionLiteral::kAccessorOrMethod, language_mode(),
         CHECK_OK_CUSTOM(EmptyObjectLiteralProperty));
 
     // Make sure the name expression is a string since we need a Name for
@@ skipping 267 matching lines @@
 
   // "expression" was not itself an arrow function parameter list, but it might
   // form part of one.  Propagate speculative formal parameter error locations.
   // Do not merge pending non-pattern expressions yet!
   classifier->Accumulate(
       &arrow_formals_classifier,
       ExpressionClassifier::ExpressionProductions |
           ExpressionClassifier::PatternProductions |
           ExpressionClassifier::FormalParametersProductions |
           ExpressionClassifier::CoverInitializedNameProduction |
+          ExpressionClassifier::AnnexBDuplicateProtoProduction |
           ExpressionClassifier::AsyncArrowFormalParametersProduction,
       false);
 
   if (!Token::IsAssignmentOp(peek())) {
     // Parsed conditional expression only (no assignment).
     // Now pending non-pattern expressions must be merged.
     classifier->MergeNonPatterns(&arrow_formals_classifier);
     return expression;
   }
 
   // Now pending non-pattern expressions must be discarded.
   arrow_formals_classifier.Discard();
 
   CheckNoTailCallExpressions(classifier, CHECK_OK);
 
   if (IsValidPattern(expression) && peek() == Token::ASSIGN) {
     classifier->ForgiveCoverInitializedNameError();
+    classifier->ForgiveAnnexBDuplicateProtoError();
     ValidateAssignmentPattern(classifier, CHECK_OK);
     is_destructuring_assignment = true;
   } else {
     expression = this->CheckAndRewriteReferenceExpression(
         expression, lhs_beg_pos, scanner()->location().end_pos,
         MessageTemplate::kInvalidLhsInAssignment, CHECK_OK);
   }
 
   expression = this->MarkExpressionAsAssigned(expression);
 
   Token::Value op = Next();  // Get assignment operator.
   if (op != Token::ASSIGN) {
     classifier->RecordPatternError(scanner()->location(),
                                    MessageTemplate::kUnexpectedToken,
                                    Token::String(op));
   }
   int pos = position();
 
   ExpressionClassifier rhs_classifier(this);
 
   ExpressionT right =
       this->ParseAssignmentExpression(accept_IN, &rhs_classifier, CHECK_OK);
   CheckNoTailCallExpressions(&rhs_classifier, CHECK_OK);
   Traits::RewriteNonPattern(&rhs_classifier, CHECK_OK);
   classifier->Accumulate(
       &rhs_classifier,
       ExpressionClassifier::ExpressionProductions |
           ExpressionClassifier::CoverInitializedNameProduction |
+          ExpressionClassifier::AnnexBDuplicateProtoProduction |
           ExpressionClassifier::AsyncArrowFormalParametersProduction);
 
   // TODO(1231235): We try to estimate the set of properties set by
   // constructors. We define a new property whenever there is an
   // assignment to a property of 'this'. We should probably only add
   // properties if we haven't seen them before. Otherwise we'll
   // probably overestimate the number of properties.
   if (op == Token::ASSIGN && this->IsThisProperty(expression)) {
     function_state_->AddProperty();
   }
@@ skipping 1220 matching lines @@
   }
 }
 
 
 #undef CHECK_OK
 #undef CHECK_OK_CUSTOM
 
 template <typename Traits>
 void ParserBase<Traits>::ObjectLiteralChecker::CheckProperty(
     Token::Value property, PropertyKind type, MethodKind method_type,
-    bool* ok) {
+    ExpressionClassifier* classifier, bool* ok) {
   DCHECK(!IsStaticMethod(method_type));
   DCHECK(!IsSpecialMethod(method_type) || type == kMethodProperty);
 
   if (property == Token::SMI || property == Token::NUMBER) return;
 
   if (type == kValueProperty && IsProto()) {
     if (has_seen_proto_) {
-      this->parser()->ReportMessage(MessageTemplate::kDuplicateProto);
-      *ok = false;
+      classifier->RecordAnnexBDuplicateProtoError(
+          this->scanner()->location(), MessageTemplate::kDuplicateProto);
       return;
     }
     has_seen_proto_ = true;
-    return;
   }
 }
 
 template <typename Traits>
 void ParserBase<Traits>::ClassLiteralChecker::CheckProperty(
     Token::Value property, PropertyKind type, MethodKind method_type,
-    bool* ok) {
+    ExpressionClassifier* classifier, bool* ok) {
   DCHECK(type == kMethodProperty || type == kAccessorProperty);
 
   if (property == Token::SMI || property == Token::NUMBER) return;
 
   if (IsStaticMethod(method_type)) {
     if (IsPrototype()) {
       this->parser()->ReportMessage(MessageTemplate::kStaticPrototype);
       *ok = false;
       return;
     }
@@ skipping 17 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H