Re-apply formal argument, arrow function parsing refactors

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index 0440d831eea5105552c2c268534faead9ff44f0e..920052daf2550a7b3bac500b391785a6a7a734e3 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -17,6 +17,26 @@
 namespace v8 {
 namespace internal {
 
+
+// When parsing the formal parameters of a function, we usually don't yet know
+// if the function will be strict, so we cannot yet produce errors for
+// parameter names or duplicates.  Instead, we remember the locations of these
+// errors if they occur and produce the errors later.
+class FormalParameterErrorLocations BASE_EMBEDDED {
+ public:
+  FormalParameterErrorLocations()
+      : eval_or_arguments(Scanner::Location::invalid()),
+        undefined(Scanner::Location::invalid()),
+        duplicate(Scanner::Location::invalid()),
+        reserved(Scanner::Location::invalid()) {}
+
+  Scanner::Location eval_or_arguments;
+  Scanner::Location undefined;
+  Scanner::Location duplicate;
+  Scanner::Location reserved;
+};
+
+
 // Common base class shared between parser and pre-parser. Traits encapsulate
 // the differences between Parser and PreParser:
 
@@ -51,6 +71,8 @@ namespace internal {
 //     typedef Literal;
 //     typedef ExpressionList;
 //     typedef PropertyList;
+//     typedef FormalParameter;
+//     typedef FormalParameterScope;
 //     // For constructing objects returned by the traversing functions.
 //     typedef Factory;
 //   };
@@ -63,6 +85,8 @@ class ParserBase : public Traits {
   // Shorten type names defined by Traits.
   typedef typename Traits::Type::Expression ExpressionT;
   typedef typename Traits::Type::Identifier IdentifierT;
+  typedef typename Traits::Type::FormalParameter FormalParameterT;
+  typedef typename Traits::Type::FormalParameterScope FormalParameterScopeT;
   typedef typename Traits::Type::FunctionLiteral FunctionLiteralT;
   typedef typename Traits::Type::Literal LiteralT;
   typedef typename Traits::Type::ObjectLiteralProperty ObjectLiteralPropertyT;
@@ -495,31 +519,28 @@ class ParserBase : public Traits {
   // after parsing the function, since the function can declare itself strict.
   void CheckFunctionParameterNames(LanguageMode language_mode,
                                    bool strict_params,
-                                   const Scanner::Location& eval_args_loc,
-                                   const Scanner::Location& undefined_loc,
-                                   const Scanner::Location& dupe_loc,
-                                   const Scanner::Location& reserved_loc,
+                                   const FormalParameterErrorLocations& locs,
                                    bool* ok) {
     if (is_sloppy(language_mode) && !strict_params) return;
-    if (is_strict(language_mode) && eval_args_loc.IsValid()) {
-      Traits::ReportMessageAt(eval_args_loc, "strict_eval_arguments");
+    if (is_strict(language_mode) && locs.eval_or_arguments.IsValid()) {
+      Traits::ReportMessageAt(locs.eval_or_arguments, "strict_eval_arguments");
       *ok = false;
       return;
     }
-    if (is_strong(language_mode) && undefined_loc.IsValid()) {
-      Traits::ReportMessageAt(undefined_loc, "strong_undefined");
+    if (is_strict(language_mode) && locs.reserved.IsValid()) {
+      Traits::ReportMessageAt(locs.reserved, "unexpected_strict_reserved");
       *ok = false;
       return;
     }
-    // TODO(arv): When we add support for destructuring in setters we also need
-    // to check for duplicate names.
-    if (dupe_loc.IsValid()) {
-      Traits::ReportMessageAt(dupe_loc, "strict_param_dupe");
+    if (is_strong(language_mode) && locs.undefined.IsValid()) {
+      Traits::ReportMessageAt(locs.undefined, "strong_undefined");
       *ok = false;
       return;
     }
-    if (reserved_loc.IsValid()) {
-      Traits::ReportMessageAt(reserved_loc, "unexpected_strict_reserved");
+    // TODO(arv): When we add support for destructuring in setters we also need
+    // to check for duplicate names.
+    if (locs.duplicate.IsValid()) {
+      Traits::ReportMessageAt(locs.duplicate, "strict_param_dupe");
       *ok = false;
       return;
     }
@@ -600,12 +621,23 @@ class ParserBase : public Traits {
   ExpressionT ParseMemberExpression(bool* ok);
   ExpressionT ParseMemberExpressionContinuation(ExpressionT expression,
                                                 bool* ok);
-  ExpressionT ParseArrowFunctionLiteral(int start_pos, ExpressionT params_ast,
-                                        bool* ok);
+  ExpressionT ParseArrowFunctionLiteral(
+      Scope* function_scope, const FormalParameterErrorLocations& error_locs,
+      bool has_rest, bool* ok);
   ExpressionT ParseTemplateLiteral(ExpressionT tag, int start, bool* ok);
   void AddTemplateExpression(ExpressionT);
   ExpressionT ParseSuperExpression(bool is_new, bool* ok);
 
+  void ParseFormalParameter(FormalParameterScopeT* scope,
+                            FormalParameterErrorLocations* locs, bool is_rest,
+                            bool* ok);
+  int ParseFormalParameterList(FormalParameterScopeT* scope,
+                               FormalParameterErrorLocations* locs,
+                               bool* has_rest, bool* ok);
+  void CheckArityRestrictions(
+      int param_count, FunctionLiteral::ArityRestriction arity_restriction,
+      int formals_start_pos, int formals_end_pos, bool* ok);
+
   // Checks if the expression is a valid reference expression (e.g., on the
   // left-hand side of assignments). Although ruled out by ECMA as early errors,
   // we allow calls for web compatibility and rewrite them to a runtime throw.
@@ -815,12 +847,6 @@ class PreParserExpression {
         IsValidArrowParamListField::encode(valid_arrow_param_list));
   }
 
-  static PreParserExpression EmptyArrowParamList() {
-    // Any expression for which IsValidArrowParamList() returns true
-    // will work here.
-    return FromIdentifier(PreParserIdentifier::Default());
-  }
-
   static PreParserExpression StringLiteral() {
     return PreParserExpression(TypeField::encode(kStringLiteralExpression));
   }
@@ -911,20 +937,27 @@ class PreParserExpression {
     return IsIdentifier() || IsProperty();
   }
 
-  bool IsValidArrowParamList(Scanner::Location* undefined_loc) const {
+  bool IsValidArrowParamList(FormalParameterErrorLocations* locs,
+                             const Scanner::Location& params_loc) const {
     ValidArrowParam valid = ValidateArrowParams();
     if (ParenthesizationField::decode(code_) == kMultiParenthesizedExpression) {
       return false;
     }
-    if (valid == kValidArrowParam) {
-      return true;
-    } else if (valid == kInvalidStrongArrowParam) {
-      // Return true for now regardless of strong mode for compatibility with
-      // parser.
-      *undefined_loc = Scanner::Location();
-      return true;
-    } else {
-      return false;
+    switch (valid) {
+      case kInvalidArrowParam:
+        return false;
+      case kInvalidStrongArrowParam:
+        locs->undefined = params_loc;
+        return true;
+      case kInvalidStrictReservedArrowParam:
+        locs->reserved = params_loc;
+        return true;
+      case kInvalidStrictEvalArgumentsArrowParam:
+        locs->eval_or_arguments = params_loc;
+        return true;
+      default:
+        DCHECK_EQ(valid, kValidArrowParam);
+        return true;
     }
   }
 
@@ -991,8 +1024,12 @@ class PreParserExpression {
     kNoTemplateTagExpression
   };
 
+  // These validity constraints are ordered such that a value of N implies lack
+  // of errors M < N.
   enum ValidArrowParam {
     kInvalidArrowParam,
+    kInvalidStrictEvalArgumentsArrowParam,
+    kInvalidStrictReservedArrowParam,
     kInvalidStrongArrowParam,
     kValidArrowParam
   };
@@ -1008,13 +1045,16 @@ class PreParserExpression {
       return kInvalidArrowParam;
     }
     PreParserIdentifier ident = AsIdentifier();
-    // A valid identifier can be an arrow function parameter
-    // except for eval, arguments, yield, and reserved keywords.
-    if (ident.IsEval() || ident.IsArguments() ||
-        ident.IsFutureStrictReserved()) {
-      return kInvalidArrowParam;
+    // In strict mode, eval and arguments are not valid formal parameter names.
+    if (ident.IsEval() || ident.IsArguments()) {
+      return kInvalidStrictEvalArgumentsArrowParam;
+    }
+    // In strict mode, future reserved words are not valid either, and as they
+    // produce different errors we allot them their own error code.
+    if (ident.IsFutureStrictReserved()) {
+      return kInvalidStrictReservedArrowParam;
     }
-    // In strong mode, 'undefined' is similarly restricted.
+    // In strong mode, 'undefined' isn't a valid formal parameter name either.
     if (ident.IsUndefined()) {
       return kInvalidStrongArrowParam;
     }
@@ -1031,7 +1071,7 @@ class PreParserExpression {
       ExpressionTypeField;
   typedef BitField<bool, ParenthesizationField::kNext, 1> IsUseStrictField;
   typedef BitField<bool, IsUseStrictField::kNext, 1> IsUseStrongField;
-  typedef BitField<ValidArrowParam, ParenthesizationField::kNext, 2>
+  typedef BitField<ValidArrowParam, ParenthesizationField::kNext, 3>
       IsValidArrowParamListField;
   typedef BitField<PreParserIdentifier::Type, ParenthesizationField::kNext, 10>
       IdentifierTypeField;
@@ -1040,20 +1080,24 @@ class PreParserExpression {
 };
 
 
-// PreParserExpressionList doesn't actually store the expressions because
-// PreParser doesn't need to.
-class PreParserExpressionList {
+// The pre-parser doesn't need to build lists of expressions, identifiers, or
+// the like.
+template <typename T>
+class PreParserList {
  public:
   // These functions make list->Add(some_expression) work (and do nothing).
-  PreParserExpressionList() : length_(0) {}
-  PreParserExpressionList* operator->() { return this; }
-  void Add(PreParserExpression, void*) { ++length_; }
+  PreParserList() : length_(0) {}
+  PreParserList* operator->() { return this; }
+  void Add(T, void*) { ++length_; }
   int length() const { return length_; }
  private:
   int length_;
 };
 
 
+typedef PreParserList<PreParserExpression> PreParserExpressionList;
+
+
 class PreParserStatement {
  public:
   static PreParserStatement Default() {
@@ -1118,16 +1162,7 @@ class PreParserStatement {
 };
 
 
-
-// PreParserStatementList doesn't actually store the statements because
-// the PreParser does not need them.
-class PreParserStatementList {
- public:
-  // These functions make list->Add(some_expression) work as no-ops.
-  PreParserStatementList() {}
-  PreParserStatementList* operator->() { return this; }
-  void Add(PreParserStatement, void*) {}
-};
+typedef PreParserList<PreParserStatement> PreParserStatementList;
 
 
 class PreParserFactory {
@@ -1292,6 +1327,8 @@ class PreParserTraits {
     typedef PreParserExpression Literal;
     typedef PreParserExpressionList ExpressionList;
     typedef PreParserExpressionList PropertyList;
+    typedef PreParserIdentifier FormalParameter;
+    typedef DuplicateFinder FormalParameterScope;
     typedef PreParserStatementList StatementList;
 
     // For constructing objects returned by the traversing functions.
@@ -1391,6 +1428,9 @@ class PreParserTraits {
     return expression;
   }
 
+  V8_INLINE bool IsDeclared(DuplicateFinder* duplicate_finder,

[wingo, 2015/04/21 09:32:25]

This decl is vestigial, will remove.

+                            PreParserIdentifier current_identifier);
+
   bool ShortcutNumericLiteralBinaryExpression(PreParserExpression* x,
                                               PreParserExpression y,
                                               Token::Value op,
@@ -1435,9 +1475,6 @@ class PreParserTraits {
   static PreParserExpression EmptyExpression() {
     return PreParserExpression::Default();
   }
-  static PreParserExpression EmptyArrowParamList() {
-    return PreParserExpression::EmptyArrowParamList();
-  }
   static PreParserExpression EmptyLiteral() {
     return PreParserExpression::Default();
   }
@@ -1525,16 +1562,10 @@ class PreParserTraits {
                          Variable* fvar, Token::Value fvar_init_op,
                          FunctionKind kind, bool* ok);
 
-  // Utility functions
-  int DeclareArrowParametersFromExpression(PreParserExpression expression,
-                                           Scope* scope,
-                                           Scanner::Location* undefined_loc,
-                                           Scanner::Location* dupe_loc,
-                                           bool* ok) {
-    // TODO(aperez): Detect duplicated identifiers in paramlists.
-    *ok = expression.IsValidArrowParamList(undefined_loc);
-    return 0;
-  }
+  V8_INLINE void ParseArrowFunctionFormalParameters(
+      Scope* scope, PreParserExpression expression,
+      const Scanner::Location& params_loc,
+      FormalParameterErrorLocations* error_locs, bool* is_rest, bool* ok);
 
   struct TemplateLiteralState {};
 
@@ -1560,6 +1591,10 @@ class PreParserTraits {
     return !tag.IsNoTemplateTag();
   }
 
+  V8_INLINE bool DeclareFormalParameter(DuplicateFinder* scope,
+                                        PreParserIdentifier param,
+                                        bool is_rest);
+
   void CheckConflictingVarDeclarations(Scope* scope, bool* ok) {}
 
   // Temporary glue; these functions will move to ParserBase.
@@ -1748,6 +1783,27 @@ PreParserExpression PreParserTraits::SpreadCallNew(PreParserExpression function,
 }
 
 
+bool PreParserTraits::DeclareFormalParameter(
+    DuplicateFinder* duplicate_finder, PreParserIdentifier current_identifier,
+    bool is_rest) {
+  return pre_parser_->scanner()->FindSymbol(duplicate_finder, 1) != 0;
+}
+
+
+void PreParserTraits::ParseArrowFunctionFormalParameters(
+    Scope* scope, PreParserExpression params,
+    const Scanner::Location& params_loc,
+    FormalParameterErrorLocations* error_locs, bool* is_rest, bool* ok) {
+  // TODO(wingo): Detect duplicated identifiers in paramlists.  Detect parameter
+  // lists that are too long.
+  if (!params.IsValidArrowParamList(error_locs, params_loc)) {
+    *ok = false;
+    ReportMessageAt(params_loc, "malformed_arrow_function_parameter_list");
+    return;
+  }
+}
+
+
 PreParserStatementList PreParser::ParseEagerFunctionBody(
     PreParserIdentifier function_name, int pos, Variable* fvar,
     Token::Value fvar_init_op, FunctionKind kind, bool* ok) {
@@ -2043,12 +2099,14 @@ ParserBase<Traits>::ParsePrimaryExpression(bool* ok) {
 
     case Token::LPAREN:
       Consume(Token::LPAREN);
-      if (allow_harmony_arrow_functions() && peek() == Token::RPAREN) {
-        // Arrow functions are the only expression type constructions
-        // for which an empty parameter list "()" is valid input.
-        Consume(Token::RPAREN);
-        result = this->ParseArrowFunctionLiteral(
-            beg_pos, this->EmptyArrowParamList(), CHECK_OK);
+      if (allow_harmony_arrow_functions() && Check(Token::RPAREN)) {
+        // As a primary expression, the only thing that can follow "()" is "=>".
+        Scope* scope = this->NewScope(scope_, ARROW_SCOPE);
+        scope->set_start_position(beg_pos);
+        FormalParameterErrorLocations error_locs;
+        bool has_rest = false;
+        result = this->ParseArrowFunctionLiteral(scope, error_locs, has_rest,
+                                                 CHECK_OK);
       } else {
         // Heuristically try to detect immediately called functions before
         // seeing the call parentheses.
@@ -2506,8 +2564,15 @@ ParserBase<Traits>::ParseAssignmentExpression(bool accept_IN, bool* ok) {
 
   if (allow_harmony_arrow_functions() && peek() == Token::ARROW) {
     checkpoint.Restore();
-    expression = this->ParseArrowFunctionLiteral(lhs_location.beg_pos,
-                                                 expression, CHECK_OK);
+    FormalParameterErrorLocations error_locs;
+    Scanner::Location loc(lhs_location.beg_pos, scanner()->location().end_pos);
+    bool has_rest = false;
+    Scope* scope = this->NewScope(scope_, ARROW_SCOPE);
+    scope->set_start_position(lhs_location.beg_pos);
+    this->ParseArrowFunctionFormalParameters(scope, expression, loc,
+                                             &error_locs, &has_rest, CHECK_OK);
+    expression =
+        this->ParseArrowFunctionLiteral(scope, error_locs, has_rest, CHECK_OK);
     return expression;
   }
 
@@ -3041,10 +3106,106 @@ ParserBase<Traits>::ParseMemberExpressionContinuation(ExpressionT expression,
 
 
 template <class Traits>
+void ParserBase<Traits>::ParseFormalParameter(
+    FormalParameterScopeT* scope, FormalParameterErrorLocations* locs,
+    bool is_rest, bool* ok) {
+  // FormalParameter[Yield,GeneratorParameter] :
+  //   BindingElement[?Yield, ?GeneratorParameter]
+  bool is_strict_reserved;
+  IdentifierT name =
+      ParseIdentifierOrStrictReservedWord(&is_strict_reserved, ok);
+  if (!*ok) return;
+
+  // Store locations for possible future error reports.
+  if (!locs->eval_or_arguments.IsValid() && this->IsEvalOrArguments(name)) {
+    locs->eval_or_arguments = scanner()->location();
+  }
+  if (!locs->undefined.IsValid() && this->IsUndefined(name)) {
+    locs->undefined = scanner()->location();
+  }
+  if (!locs->reserved.IsValid() && is_strict_reserved) {
+    locs->reserved = scanner()->location();
+  }
+  bool was_declared = Traits::DeclareFormalParameter(scope, name, is_rest);
+  if (!locs->duplicate.IsValid() && was_declared) {
+    locs->duplicate = scanner()->location();
+  }
+}
+
+
+template <class Traits>
+int ParserBase<Traits>::ParseFormalParameterList(
+    FormalParameterScopeT* scope, FormalParameterErrorLocations* locs,
+    bool* is_rest, bool* ok) {
+  // FormalParameters[Yield,GeneratorParameter] :
+  //   [empty]
+  //   FormalParameterList[?Yield, ?GeneratorParameter]
+  //
+  // FormalParameterList[Yield,GeneratorParameter] :
+  //   FunctionRestParameter[?Yield]
+  //   FormalsList[?Yield, ?GeneratorParameter]
+  //   FormalsList[?Yield, ?GeneratorParameter] , FunctionRestParameter[?Yield]
+  //
+  // FormalsList[Yield,GeneratorParameter] :
+  //   FormalParameter[?Yield, ?GeneratorParameter]
+  //   FormalsList[?Yield, ?GeneratorParameter] ,
+  //     FormalParameter[?Yield,?GeneratorParameter]
+
+  int parameter_count = 0;
+
+  if (peek() != Token::RPAREN) {
+    do {
+      if (++parameter_count > Code::kMaxArguments) {
+        ReportMessage("too_many_parameters");
+        *ok = false;
+        return -1;
+      }
+      *is_rest = allow_harmony_rest_params() && Check(Token::ELLIPSIS);
+      ParseFormalParameter(scope, locs, *is_rest, ok);
+      if (!*ok) return -1;
+    } while (!*is_rest && Check(Token::COMMA));
+
+    if (*is_rest && peek() == Token::COMMA) {
+      ReportMessageAt(scanner()->peek_location(), "param_after_rest");
+      *ok = false;
+      return -1;
+    }
+  }
+
+  return parameter_count;
+}
+
+
+template <class Traits>
+void ParserBase<Traits>::CheckArityRestrictions(
+    int param_count, FunctionLiteral::ArityRestriction arity_restriction,
+    int formals_start_pos, int formals_end_pos, bool* ok) {
+  switch (arity_restriction) {
+    case FunctionLiteral::GETTER_ARITY:
+      if (param_count != 0) {
+        ReportMessageAt(Scanner::Location(formals_start_pos, formals_end_pos),
+                        "bad_getter_arity");
+        *ok = false;
+      }
+      break;
+    case FunctionLiteral::SETTER_ARITY:
+      if (param_count != 1) {
+        ReportMessageAt(Scanner::Location(formals_start_pos, formals_end_pos),
+                        "bad_setter_arity");
+        *ok = false;
+      }
+      break;
+    default:
+      break;
+  }
+}
+
+
+template <class Traits>
 typename ParserBase<Traits>::ExpressionT
-ParserBase<Traits>::ParseArrowFunctionLiteral(int start_pos,
-                                              ExpressionT params_ast,
-                                              bool* ok) {
+ParserBase<Traits>::ParseArrowFunctionLiteral(
+    Scope* scope, const FormalParameterErrorLocations& error_locs,
+    bool has_rest, bool* ok) {
   if (peek() == Token::ARROW && scanner_->HasAnyLineTerminatorBeforeNext()) {
     // ASI inserts `;` after arrow parameters if a line terminator is found.
     // `=> ...` is never a valid expression, so report as syntax error.
@@ -3054,9 +3215,8 @@ ParserBase<Traits>::ParseArrowFunctionLiteral(int start_pos,
     return this->EmptyExpression();
   }
 
-  Scope* scope = this->NewScope(scope_, ARROW_SCOPE);
   typename Traits::Type::StatementList body;
-  int num_parameters = -1;
+  int num_parameters = scope->num_parameters();
   int materialized_literal_count = -1;
   int expected_property_count = -1;
   int handler_count = 0;
@@ -3066,29 +3226,6 @@ ParserBase<Traits>::ParseArrowFunctionLiteral(int start_pos,
     typename Traits::Type::Factory function_factory(ast_value_factory());
     FunctionState function_state(&function_state_, &scope_, scope,
                                  kArrowFunction, &function_factory);
-    Scanner::Location undefined_loc = Scanner::Location::invalid();
-    Scanner::Location dupe_loc = Scanner::Location::invalid();
-    // TODO(arv): Pass in eval_args_loc and reserved_loc here.
-    num_parameters = Traits::DeclareArrowParametersFromExpression(
-        params_ast, scope_, &undefined_loc, &dupe_loc, ok);
-    if (!*ok) {
-      ReportMessageAt(
-          Scanner::Location(start_pos, scanner()->location().beg_pos),
-          "malformed_arrow_function_parameter_list");
-      return this->EmptyExpression();
-    }
-
-    if (undefined_loc.IsValid()) {
-      // Workaround for preparser not keeping track of positions.
-      undefined_loc = Scanner::Location(start_pos,
-                                        scanner()->location().end_pos);
-    }
-    if (num_parameters > Code::kMaxArguments) {
-      ReportMessageAt(Scanner::Location(params_ast->position(), position()),
-                      "too_many_parameters");
-      *ok = false;
-      return this->EmptyExpression();
-    }
 
     Expect(Token::ARROW, CHECK_OK);
 
@@ -3124,23 +3261,20 @@ ParserBase<Traits>::ParseArrowFunctionLiteral(int start_pos,
     }
     super_loc = function_state.super_call_location();
 
-    scope->set_start_position(start_pos);
     scope->set_end_position(scanner()->location().end_pos);
 
-    // Arrow function *parameter lists* are always checked as in strict mode.
-    // TODO(arv): eval_args_loc and reserved_loc needs to be set by
-    // DeclareArrowParametersFromExpression.
-    Scanner::Location eval_args_loc = Scanner::Location::invalid();
-    Scanner::Location reserved_loc = Scanner::Location::invalid();
+    // Arrow function formal parameters are parsed as StrictFormalParameterList,
+    // which is not the same as "parameters of a strict function"; it only means
+    // that duplicates are not allowed.  Of course, the arrow function may
+    // itself be strict as well.
     const bool use_strict_params = true;
     this->CheckFunctionParameterNames(language_mode(), use_strict_params,
-                                      eval_args_loc, undefined_loc, dupe_loc,
-                                      reserved_loc, CHECK_OK);
+                                      error_locs, CHECK_OK);
 
     // Validate strict mode.
     if (is_strict(language_mode())) {
-      CheckStrictOctalLiteral(start_pos, scanner()->location().end_pos,
-                              CHECK_OK);
+      CheckStrictOctalLiteral(scope->start_position(),
+                              scanner()->location().end_pos, CHECK_OK);
       this->CheckConflictingVarDeclarations(scope, CHECK_OK);
     }
   }
@@ -3151,9 +3285,9 @@ ParserBase<Traits>::ParseArrowFunctionLiteral(int start_pos,
       num_parameters, FunctionLiteral::kNoDuplicateParameters,
       FunctionLiteral::ANONYMOUS_EXPRESSION, FunctionLiteral::kIsFunction,
       FunctionLiteral::kNotParenthesized, FunctionKind::kArrowFunction,
-      start_pos);
+      scope->start_position());
 
-  function_literal->set_function_token_position(start_pos);
+  function_literal->set_function_token_position(scope->start_position());
   if (super_loc.IsValid()) function_state_->set_super_call_location(super_loc);
 
   if (fni_ != NULL) this->InferFunctionName(fni_, function_literal);