Implement proper scoping for "this" in arrow functions

src/parser.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/ast.h"
 #include "src/bailout-reason.h"
 #include "src/base/platform/platform.h"
@@ skipping 655 matching lines @@
 }
 
 
 const AstRawString* ParserTraits::GetNextSymbol(Scanner* scanner) {
   return parser_->scanner()->NextSymbol(parser_->ast_value_factory());
 }
 
 
 Expression* ParserTraits::ThisExpression(Scope* scope, AstNodeFactory* factory,
                                          int pos) {
-  return factory->NewVariableProxy(scope->receiver(), pos);
+  return scope->NewUnresolved(factory,
+                              parser_->ast_value_factory()->this_string(),
+                              Variable::THIS, pos);
 }
 
 Expression* ParserTraits::SuperReference(Scope* scope, AstNodeFactory* factory,
                                          int pos) {
   return factory->NewSuperReference(
       ThisExpression(scope, factory, pos)->AsVariableProxy(),
       pos);
 }
 
 
@@ skipping 27 matching lines @@
 Expression* ParserTraits::ExpressionFromIdentifier(const AstRawString* name,
                                                    int pos, Scope* scope,
                                                    AstNodeFactory* factory) {
   if (parser_->fni_ != NULL) parser_->fni_->PushVariableName(name);
 
   // Arrow function parameters are parsed as an expression. When
   // parsing lazily, it is enough to create a VariableProxy in order
   // for Traits::DeclareArrowParametersFromExpression() to be able to
   // pick the names of the parameters.
   return parser_->parsing_lazy_arrow_parameters_
-             ? factory->NewVariableProxy(name, false, pos)
-             : scope->NewUnresolved(factory, name, pos);
+             ? factory->NewVariableProxy(name, Variable::NORMAL, pos)
+             : scope->NewUnresolved(factory, name, Variable::NORMAL, pos);
 }
 
 
 Expression* ParserTraits::ExpressionFromString(int pos, Scanner* scanner,
                                                AstNodeFactory* factory) {
   const AstRawString* symbol = GetSymbol(scanner);
   if (parser_->fni_ != NULL) parser_->fni_->PushLiteralName(symbol);
   return factory->NewStringLiteral(symbol, pos);
 }
 
@@ skipping 1049 matching lines @@
 }
 
 
 VariableProxy* Parser::NewUnresolved(const AstRawString* name,
                                      VariableMode mode) {
   // If we are inside a function, a declaration of a var/const variable is a
   // truly local variable, and the scope of the variable is always the function
   // scope.
   // Let/const variables in harmony mode are always added to the immediately
   // enclosing scope.
-  return DeclarationScope(mode)->NewUnresolved(factory(), name, position());
+  return DeclarationScope(mode)
+      ->NewUnresolved(factory(), name, Variable::NORMAL, position());
 }
 
 
 void Parser::Declare(Declaration* declaration, bool resolve, bool* ok) {
   VariableProxy* proxy = declaration->proxy();
   DCHECK(proxy->raw_name() != NULL);
   const AstRawString* name = proxy->raw_name();
   VariableMode mode = declaration->mode();
   Scope* declaration_scope = DeclarationScope(mode);
   Variable* var = NULL;
@@ skipping 64 matching lines @@
   // same variable if it is declared several times. This is not a
   // semantic issue as long as we keep the source order, but it may be
   // a performance issue since it may lead to repeated
   // RuntimeHidden_DeclareLookupSlot calls.
   declaration_scope->AddDeclaration(declaration);
 
   if (mode == CONST_LEGACY && declaration_scope->is_script_scope()) {
     // For global const variables we bind the proxy to a variable.
     DCHECK(resolve);  // should be set by all callers
     Variable::Kind kind = Variable::NORMAL;
-    var = new (zone()) Variable(declaration_scope, name, mode, true, kind,
+    var = new (zone()) Variable(declaration_scope, name, mode, kind,
                                 kNeedsInitialization, kNotAssigned);
   } else if (declaration_scope->is_eval_scope() &&
              is_sloppy(declaration_scope->language_mode())) {
     // For variable declarations in a sloppy eval scope the proxy is bound
     // to a lookup variable to force a dynamic declaration using the
     // DeclareLookupSlot runtime function.
     Variable::Kind kind = Variable::NORMAL;
     // TODO(sigurds) figure out if kNotAssigned is OK here
-    var = new (zone()) Variable(declaration_scope, name, mode, true, kind,
+    var = new (zone()) Variable(declaration_scope, name, mode, kind,
                                 declaration->initialization(), kNotAssigned);
     var->AllocateTo(Variable::LOOKUP, -1);
     resolve = true;
   }
 
   // If requested and we have a local variable, bind the proxy to the variable
   // at parse-time. This is used for functions (and consts) declared inside
   // statements: the corresponding function (or const) variable must be in the
   // function scope and not a statement-local scope, e.g. as provided with a
   // 'with' statement:
@@ skipping 501 matching lines @@
       value = NULL;
     }
 
     // Add an assignment node to the initialization statement block if we still
     // have a pending initialization value.
     if (value != NULL) {
       DCHECK(mode == VAR);
       // 'var' initializations are simply assignments (with all the consequences
       // if they are inside a 'with' statement - they may change a 'with' object
       // property).
-      VariableProxy* proxy =
-          initialization_scope->NewUnresolved(factory(), name);
+      VariableProxy* proxy = initialization_scope->NewUnresolved(
+          factory(), name, Variable::NORMAL);
       Assignment* assignment =
           factory()->NewAssignment(init_op, proxy, value, pos);
       block->AddStatement(
           factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition),
           zone());
     }
 
     if (fni_ != NULL) fni_->Leave();
   } while (peek() == Token::COMMA);
 
@@ skipping 841 matching lines @@
 
       if (name != NULL && CheckInOrOf(accept_OF, &mode, ok)) {
         if (!*ok) return nullptr;
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
         Expression* enumerable = ParseExpression(true, CHECK_OK);
         Expect(Token::RPAREN, CHECK_OK);
 
-        VariableProxy* each = scope_->NewUnresolved(factory(), name, each_pos);
+        VariableProxy* each =
+            scope_->NewUnresolved(factory(), name, Variable::NORMAL, each_pos);
         Statement* body = ParseSubStatement(NULL, CHECK_OK);
         InitializeForEachStatement(loop, each, enumerable, body);
         Block* result =
             factory()->NewBlock(NULL, 2, false, RelocInfo::kNoPosition);
         result->AddStatement(variable_statement, zone());
         result->AddStatement(loop, zone());
         scope_ = saved_scope;
         for_scope->set_end_position(scanner()->location().end_pos);
         for_scope = for_scope->FinalizeBlockScope();
         DCHECK(for_scope == NULL);
@@ skipping 39 matching lines @@
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
         // The expression does not see the loop variable.
         scope_ = saved_scope;
         Expression* enumerable = ParseExpression(true, CHECK_OK);
         scope_ = for_scope;
         Expect(Token::RPAREN, CHECK_OK);
 
-        VariableProxy* each = scope_->NewUnresolved(factory(), name, each_pos);
+        VariableProxy* each =
+            scope_->NewUnresolved(factory(), name, Variable::NORMAL, each_pos);
         Statement* body = ParseSubStatement(NULL, CHECK_OK);
         Block* body_block =
             factory()->NewBlock(NULL, 3, false, RelocInfo::kNoPosition);
         Token::Value init_op = is_const ? Token::INIT_CONST : Token::ASSIGN;
         Assignment* assignment = factory()->NewAssignment(
             init_op, each, temp_proxy, RelocInfo::kNoPosition);
         Statement* assignment_statement = factory()->NewExpressionStatement(
             assignment, RelocInfo::kNoPosition);
         body_block->AddStatement(variable_statement, zone());
         body_block->AddStatement(assignment_statement, zone());
@@ skipping 420 matching lines @@
     Token::Value fvar_init_op = Token::INIT_CONST_LEGACY;
     if (function_type == FunctionLiteral::NAMED_EXPRESSION) {
       if (allow_harmony_scoping() && is_strict(language_mode())) {
         fvar_init_op = Token::INIT_CONST;
       }
       VariableMode fvar_mode =
           allow_harmony_scoping() && is_strict(language_mode()) ? CONST
                                                                 : CONST_LEGACY;
       DCHECK(function_name != NULL);
       fvar = new (zone())
-          Variable(scope_, function_name, fvar_mode, true /* is valid LHS */,
-                   Variable::NORMAL, kCreatedInitialized, kNotAssigned);
+          Variable(scope_, function_name, fvar_mode, Variable::NORMAL,
+                   kCreatedInitialized, kNotAssigned);
       VariableProxy* proxy = factory()->NewVariableProxy(fvar);
       VariableDeclaration* fvar_declaration = factory()->NewVariableDeclaration(
           proxy, fvar_mode, scope_, RelocInfo::kNoPosition);
       scope_->DeclareFunctionVar(fvar_declaration);
     }
 
     // Determine if the function can be parsed lazily. Lazy parsing is different
     // from lazy compilation; we need to parse more eagerly than we compile.
 
     // We can only parse lazily if we also compile lazily. The heuristics for
@@ skipping 170 matching lines @@
 
 
 ZoneList<Statement*>* Parser::ParseEagerFunctionBody(
     const AstRawString* function_name, int pos, Variable* fvar,
     Token::Value fvar_init_op, FunctionKind kind, bool* ok) {
   // Everything inside an eagerly parsed function will be parsed eagerly
   // (see comment above).
   ParsingModeScope parsing_mode(this, PARSE_EAGERLY);
   ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(8, zone());
   if (fvar != NULL) {
-    VariableProxy* fproxy = scope_->NewUnresolved(factory(), function_name);
+    VariableProxy* fproxy =
+        scope_->NewUnresolved(factory(), function_name, Variable::NORMAL);
     fproxy->BindTo(fvar);
     body->Add(factory()->NewExpressionStatement(
         factory()->NewAssignment(fvar_init_op,
                                  fproxy,
                                  factory()->NewThisFunction(pos),
                                  RelocInfo::kNoPosition),
         RelocInfo::kNoPosition), zone());
   }
 
 
@@ skipping 1507 matching lines @@
     } else {
       const uc16* data = reinterpret_cast<const uc16*>(raw_string->raw_data());
       running_hash = StringHasher::ComputeRunningHash(running_hash, data,
                                                       raw_string->length());
     }
   }
 
   return running_hash;
 }
 } }  // namespace v8::internal