[es6] Implement proper TDZ for parameters

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/v8.h"
 
 #include "src/bailout-reason.h"
@@ skipping 1306 matching lines @@
       : scope(scope),
         arity(0),
         has_rest(false),
         is_simple(true),
         materialized_literals_count(0) {}
   Scope* scope;
   int arity;
   bool has_rest;
   bool is_simple;
   int materialized_literals_count;
+
+  PreParserIdentifier at(int i) { return PreParserIdentifier(); }  // Dummy
 };
 
 
 class PreParser;
 
 class PreParserTraits {
  public:
   struct Type {
     // TODO(marja): To be removed. The Traits object should contain all the data
     // it needs.
@@ skipping 262 matching lines @@
   V8_INLINE void SkipLazyFunctionBody(int* materialized_literal_count,
                                       int* expected_property_count, bool* ok) {
     UNREACHABLE();
   }
 
   V8_INLINE PreParserStatementList ParseEagerFunctionBody(
       PreParserIdentifier function_name, int pos,
       const PreParserFormalParameters& parameters,
       Variable* fvar, Token::Value fvar_init_op, FunctionKind kind, bool* ok);
 
-  V8_INLINE void ParseArrowFunctionFormalParameters(
+  V8_INLINE void ParseArrowFunctionFormalParameterList(
       PreParserFormalParameters* parameters,
       PreParserExpression expression, const Scanner::Location& params_loc,
       Scanner::Location* duplicate_loc, bool* ok);
 
   void ReindexLiterals(const PreParserFormalParameters& paramaters) {}
 
   struct TemplateLiteralState {};
 
   TemplateLiteralState OpenTemplateLiteral(int pos) {
     return TemplateLiteralState();
@@ skipping 10 matching lines @@
     return EmptyExpression();
   }
   inline void MaterializeTemplateCallsiteLiterals();
   PreParserExpression NoTemplateTag() {
     return PreParserExpression::NoTemplateTag();
   }
   static bool IsTaggedTemplate(const PreParserExpression tag) {
     return !tag.IsNoTemplateTag();
   }
 
-  void DeclareFormalParameter(PreParserFormalParameters* parameters,
-                              PreParserExpression pattern, bool is_rest,
+  void AddFormalParameter(
+      PreParserFormalParameters* parameters, PreParserExpression pattern,
+      bool is_rest) {}

[adamk, 2015/08/03 18:43:52]

One option that would make this thing slightly less brittle is if this
implementation incremented the arity, and the Parser one did the same. At the
least, it would make the Parser implementation a bit better-factored.

+  void DeclareFormalParameter(Scope* scope, PreParserIdentifier parameter,
+                              bool is_simple,
                               ExpressionClassifier* classifier) {}
 
   void CheckConflictingVarDeclarations(Scope* scope, bool* ok) {}
 
   // Temporary glue; these functions will move to ParserBase.
   PreParserExpression ParseV8Intrinsic(bool* ok);
   PreParserExpression ParseFunctionLiteral(
       PreParserIdentifier name, Scanner::Location function_name_location,
       FunctionNameValidity function_name_validity, FunctionKind kind,
       int function_token_position, FunctionLiteral::FunctionType type,
@@ skipping 177 matching lines @@
   return pre_parser_->factory()->NewCall(function, args, pos);
 }
 
 PreParserExpression PreParserTraits::SpreadCallNew(PreParserExpression function,
                                                    PreParserExpressionList args,
                                                    int pos) {
   return pre_parser_->factory()->NewCallNew(function, args, pos);
 }
 
 
-void PreParserTraits::ParseArrowFunctionFormalParameters(
+void PreParserTraits::ParseArrowFunctionFormalParameterList(
     PreParserFormalParameters* parameters,
     PreParserExpression params, const Scanner::Location& params_loc,
     Scanner::Location* duplicate_loc, bool* ok) {
   // TODO(wingo): Detect duplicated identifiers in paramlists.  Detect parameter
   // lists that are too long.
 }
 
 
 PreParserStatementList PreParser::ParseEagerFunctionBody(
     PreParserIdentifier function_name, int pos,
@@ skipping 424 matching lines @@
         FormalParametersT parameters(scope);
         scope->set_start_position(beg_pos);
         ExpressionClassifier args_classifier;
         result = this->ParseArrowFunctionLiteral(parameters, args_classifier,
                                                  CHECK_OK);
       } else if (allow_harmony_arrow_functions() &&
                  allow_harmony_rest_parameters() && Check(Token::ELLIPSIS)) {
         // (...x) => y
         Scope* scope =
             this->NewScope(scope_, ARROW_SCOPE, FunctionKind::kArrowFunction);
-        FormalParametersT parameters(scope);
+        FormalParametersT formals(scope);
         scope->set_start_position(beg_pos);
-        ExpressionClassifier args_classifier;
+        ExpressionClassifier formals_classifier;
         const bool is_rest = true;
-        this->ParseFormalParameter(is_rest, &parameters, &args_classifier,
+        this->ParseFormalParameter(is_rest, &formals, &formals_classifier,
                                    CHECK_OK);
+        Traits::DeclareFormalParameter(
+            formals.scope, formals.at(0), formals.is_simple,
+            &formals_classifier);
         if (peek() == Token::COMMA) {
           ReportMessageAt(scanner()->peek_location(),
                           MessageTemplate::kParamAfterRest);
           *ok = false;
           return this->EmptyExpression();
         }
         Expect(Token::RPAREN, CHECK_OK);
-        result = this->ParseArrowFunctionLiteral(parameters, args_classifier,
+        result = this->ParseArrowFunctionLiteral(formals, formals_classifier,
                                                  CHECK_OK);
       } else {
         // Heuristically try to detect immediately called functions before
         // seeing the call parentheses.
         parenthesized_function_ = (peek() == Token::FUNCTION);
         result = this->ParseExpression(true, classifier, CHECK_OK);
         Expect(Token::RPAREN, CHECK_OK);
       }
       break;
 
@@ skipping 531 matching lines @@
     ValidateArrowFormalParameters(&arrow_formals_classifier, expression,
                                   parenthesized_formals, CHECK_OK);
     Scanner::Location loc(lhs_location.beg_pos, scanner()->location().end_pos);
     Scope* scope =
         this->NewScope(scope_, ARROW_SCOPE, FunctionKind::kArrowFunction);
     FormalParametersT parameters(scope);
     checkpoint.Restore(&parameters.materialized_literals_count);
 
     scope->set_start_position(lhs_location.beg_pos);
     Scanner::Location duplicate_loc = Scanner::Location::invalid();
-    this->ParseArrowFunctionFormalParameters(&parameters, expression, loc,
-                                             &duplicate_loc, CHECK_OK);
+    this->ParseArrowFunctionFormalParameterList(&parameters, expression, loc,
+                                                &duplicate_loc, CHECK_OK);
     if (duplicate_loc.IsValid()) {
       arrow_formals_classifier.RecordDuplicateFormalParameterError(
           duplicate_loc);
     }
     expression = this->ParseArrowFunctionLiteral(
         parameters, arrow_formals_classifier, CHECK_OK);
     return expression;
   }
 
   // "expression" was not itself an arrow function parameter list, but it might
@@ skipping 781 matching lines @@
   if (parameters->is_simple) {
     parameters->is_simple = !is_rest && Traits::IsIdentifier(pattern);
   }
   parameters->has_rest = is_rest;
   if (is_rest && !Traits::IsIdentifier(pattern)) {
     ReportUnexpectedToken(next);
     *ok = false;
     return;
   }
   ++parameters->arity;
-  Traits::DeclareFormalParameter(parameters, pattern, is_rest, classifier);
+  Traits::AddFormalParameter(parameters, pattern, is_rest);
 }
 
 
 template <class Traits>
 void ParserBase<Traits>::ParseFormalParameterList(
     FormalParametersT* parameters, ExpressionClassifier* classifier, bool* ok) {
   // FormalParameters[Yield,GeneratorParameter] :
   //   [empty]
   //   FormalParameterList[?Yield, ?GeneratorParameter]
   //
@@ skipping 18 matching lines @@
       }
       bool is_rest = allow_harmony_rest_parameters() && Check(Token::ELLIPSIS);
       ParseFormalParameter(is_rest, parameters, classifier, ok);
       if (!*ok) return;
     } while (!parameters->has_rest && Check(Token::COMMA));
 
     if (parameters->has_rest && peek() == Token::COMMA) {
       ReportMessageAt(scanner()->peek_location(),
                       MessageTemplate::kParamAfterRest);
       *ok = false;
+      return;
     }
   }
+
+  for (int i = 0; i < parameters->arity; ++i) {
+    auto parameter = parameters->at(i);
+    Traits::DeclareFormalParameter(
+        parameters->scope, parameter, parameters->is_simple, classifier);
+  }
 }
 
 
 template <class Traits>
 void ParserBase<Traits>::CheckArityRestrictions(
     int param_count, FunctionLiteral::ArityRestriction arity_restriction,
     bool has_rest, int formals_start_pos, int formals_end_pos, bool* ok) {
   switch (arity_restriction) {
     case FunctionLiteral::GETTER_ARITY:
       if (param_count != 0) {
@@ skipping 310 matching lines @@
       *ok = false;
       return;
     }
     has_seen_constructor_ = true;
     return;
   }
 }
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H