Disallow destructuring in legacy sloppy for-in loop parsing

src/preparser.cc

 // 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.
 
 #include <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 477 matching lines @@
   return final;
 }
 
 
 PreParser::Statement PreParser::ParseVariableStatement(
     VariableDeclarationContext var_context,
     bool* ok) {
   // VariableStatement ::
   //   VariableDeclarations ';'
 
-  Statement result = ParseVariableDeclarations(var_context, nullptr, nullptr,
-                                               nullptr, CHECK_OK);
+  Statement result = ParseVariableDeclarations(
+      var_context, nullptr, nullptr, nullptr, nullptr, nullptr, CHECK_OK);
   ExpectSemicolon(CHECK_OK);
   return result;
 }
 
 
 // If the variable declaration declares exactly one non-const
 // variable, then *var is set to that variable. In all other cases,
 // *var is untouched; in particular, it is the caller's responsibility
 // to initialize it properly. This mechanism is also used for the parsing
 // of 'for-in' loops.
 PreParser::Statement PreParser::ParseVariableDeclarations(
-    VariableDeclarationContext var_context, int* num_decl,
-    Scanner::Location* first_initializer_loc, Scanner::Location* bindings_loc,
-    bool* ok) {
+    VariableDeclarationContext var_context, int* num_decl, bool* is_lexical,
+    bool* is_binding_pattern, Scanner::Location* first_initializer_loc,
+    Scanner::Location* bindings_loc, bool* ok) {
   // VariableDeclarations ::
   //   ('var' | 'const') (Identifier ('=' AssignmentExpression)?)+[',']
   //
   // The ES6 Draft Rev3 specifies the following grammar for const declarations
   //
   // ConstDeclaration ::
   //   const ConstBinding (',' ConstBinding)* ';'
   // ConstBinding ::
   //   Identifier '=' AssignmentExpression
   //
   // TODO(ES6):
   // ConstBinding ::
   //   BindingPattern '=' AssignmentExpression
   bool require_initializer = false;
   bool lexical = false;
+  bool is_pattern = false;

[Dan Ehrenberg, 2015/11/25 01:02:58]

Nit: Not sure why you moved the initialization up here; it seemed marginally
clearer before.

[adamk, 2015/11/25 01:13:12]

I moved this up to put the passing to the out-param in the same place as the
other out params (the old declaration was in an inner block).

   if (peek() == Token::VAR) {
     if (is_strong(language_mode())) {
       Scanner::Location location = scanner()->peek_location();
       ReportMessageAt(location, MessageTemplate::kStrongVar);
       *ok = false;
       return Statement::Default();
     }
     Consume(Token::VAR);
   } else if (peek() == Token::CONST && allow_const()) {
     // TODO(ES6): The ES6 Draft Rev4 section 12.2.2 reads:
@@ skipping 43 matching lines @@
         ValidateLetPattern(&pattern_classifier, CHECK_OK);
       }
 
       if (!allow_harmony_destructuring_bind() && !pattern.IsIdentifier()) {
         ReportUnexpectedToken(next);
         *ok = false;
         return Statement::Default();
       }
     }
 
-    bool is_pattern = pattern.IsObjectLiteral() || pattern.IsArrayLiteral();
+    is_pattern = pattern.IsObjectLiteral() || pattern.IsArrayLiteral();
 
     bool is_for_iteration_variable =
         var_context == kForStatement &&
         (peek() == Token::IN || PeekContextualKeyword(CStrVector("of")));
 
     Scanner::Location variable_loc = scanner()->location();
     nvars++;
     if (Check(Token::ASSIGN)) {
       ExpressionClassifier classifier;
       ParseAssignmentExpression(var_context != kForStatement, &classifier,
@@ skipping 13 matching lines @@
       *ok = false;
       return Statement::Default();
     }
   } while (peek() == Token::COMMA);
 
   if (bindings_loc) {
     *bindings_loc =
         Scanner::Location(bindings_start, scanner()->location().end_pos);
   }
 
-  if (num_decl != NULL) *num_decl = nvars;
+  if (num_decl != nullptr) *num_decl = nvars;
+  if (is_lexical != nullptr) *is_lexical = lexical;
+  if (is_binding_pattern != nullptr) *is_binding_pattern = is_pattern;
   return Statement::Default();
 }
 
 
 PreParser::Statement PreParser::ParseExpressionOrLabelledStatement(bool* ok) {
   // ExpressionStatement | LabelledStatement ::
   //   Expression ';'
   //   Identifier ':' Statement
 
   switch (peek()) {
@@ skipping 268 matching lines @@
   //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
 
   Expect(Token::FOR, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   bool is_let_identifier_expression = false;
   if (peek() != Token::SEMICOLON) {
     ForEachStatement::VisitMode mode;
     if (peek() == Token::VAR || (peek() == Token::CONST && allow_const()) ||
         (peek() == Token::LET && IsNextLetKeyword())) {
       int decl_count;
+      bool is_lexical;
+      bool is_binding_pattern;
       Scanner::Location first_initializer_loc = Scanner::Location::invalid();
       Scanner::Location bindings_loc = Scanner::Location::invalid();
-      ParseVariableDeclarations(kForStatement, &decl_count,
-                                &first_initializer_loc, &bindings_loc,
-                                CHECK_OK);
+      ParseVariableDeclarations(kForStatement, &decl_count, &is_lexical,
+                                &is_binding_pattern, &first_initializer_loc,
+                                &bindings_loc, CHECK_OK);
       bool accept_IN = decl_count >= 1;
       if (accept_IN && CheckInOrOf(&mode, ok)) {
         if (!*ok) return Statement::Default();
         if (decl_count != 1) {
           const char* loop_type =
               mode == ForEachStatement::ITERATE ? "for-of" : "for-in";
           PreParserTraits::ReportMessageAt(
               bindings_loc, MessageTemplate::kForInOfLoopMultiBindings,
               loop_type);
           *ok = false;
           return Statement::Default();
         }
         if (first_initializer_loc.IsValid() &&
-            (is_strict(language_mode()) || mode == ForEachStatement::ITERATE)) {
+            (is_strict(language_mode()) || mode == ForEachStatement::ITERATE ||
+             is_lexical || is_binding_pattern)) {
           if (mode == ForEachStatement::ITERATE) {
             ReportMessageAt(first_initializer_loc,
                             MessageTemplate::kForOfLoopInitializer);
           } else {
             // TODO(caitp): This should be an error in sloppy mode, too.
             ReportMessageAt(first_initializer_loc,
                             MessageTemplate::kForInLoopInitializer);
           }
           *ok = false;
           return Statement::Default();
@@ skipping 316 matching lines @@
     Expect(Token::RBRACE, CHECK_OK);
     return PreParserExpression::Default();
   }
 }
 
 #undef CHECK_OK
 
 
 }  // namespace internal
 }  // namespace v8