Turn Scope::locals_ into a ThreadedList

src/ast/variables.h

 // Copyright 2011 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_AST_VARIABLES_H_
 #define V8_AST_VARIABLES_H_
 
 #include "src/ast/ast-value-factory.h"
 #include "src/globals.h"
 #include "src/zone/zone.h"
@@ skipping 105 matching lines @@
     bit_field_ = LocationField::update(bit_field_, location);
     DCHECK_EQ(location, this->location());
     index_ = index;
   }
 
   static InitializationFlag DefaultInitializationFlag(VariableMode mode) {
     DCHECK(IsDeclaredVariableMode(mode));
     return mode == VAR ? kCreatedInitialized : kNeedsInitialization;
   }
 
+  typedef ThreadedList<Variable> List;
+
  private:
   Scope* scope_;
   const AstRawString* name_;
 
   // If this field is set, this variable references the stored locally bound
   // variable, but it might be shadowed by variable bindings introduced by
   // sloppy 'eval' calls between the reference scope (inclusive) and the
   // binding scope (exclusive).
   Variable* local_if_not_shadowed_;
+  Variable* next_;
   int index_;
   int initializer_position_;
   uint16_t bit_field_;
 
   class VariableModeField : public BitField16<VariableMode, 0, 3> {};
   class VariableKindField
       : public BitField16<VariableKind, VariableModeField::kNext, 3> {};
   class LocationField
       : public BitField16<VariableLocation, VariableKindField::kNext, 3> {};
   class ForceContextAllocationField
       : public BitField16<bool, LocationField::kNext, 1> {};
   class IsUsedField
       : public BitField16<bool, ForceContextAllocationField::kNext, 1> {};
   class InitializationFlagField
       : public BitField16<InitializationFlag, IsUsedField::kNext, 2> {};
   class MaybeAssignedFlagField
       : public BitField16<MaybeAssignedFlag, InitializationFlagField::kNext,
                           2> {};
+  Variable** next() { return &next_; }
+  friend List;
+  // To reset next to nullptr upon resetting after preparsing.
+  // TODO(verwaest): Remove once we properly preparse parameters.
+  friend class DeclarationScope;
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_VARIABLES_H_