[parser] Disallow Expression in for..of statements

src/parsing/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/parsing/parser.h"
 
 #include "src/api.h"
 #include "src/ast/ast.h"
 #include "src/ast/ast-expression-rewriter.h"
 #include "src/ast/ast-expression-visitor.h"
@@ skipping 3658 matching lines @@
         //     }
         //     let x;  // for TDZ
         //   }
 
         Variable* temp =
             scope_->NewTemporary(ast_value_factory()->dot_for_string());
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
-        Expression* enumerable = ParseExpression(true, CHECK_OK);
+        Expression* enumerable;
+        if (mode == ForEachStatement::ITERATE) {
+          ExpressionClassifier classifier;
+          enumerable = ParseAssignmentExpression(true, &classifier, CHECK_OK);
+          ParserTraits::RewriteNonPattern(enumerable, &classifier, CHECK_OK);

[adamk, 2016/01/20 00:35:57]

I think the calling convention here is to assign it back to the original (as I
said, this is brand new to me):

enumerable = RewriteNonPattern(...)

[mike3, 2016/01/20 17:55:40]

Acknowledged.

+        } else {
+          enumerable = ParseExpression(true, CHECK_OK);
+        }
 
         Expect(Token::RPAREN, CHECK_OK);
 
         Scope* body_scope = NewScope(scope_, BLOCK_SCOPE);
         body_scope->set_start_position(scanner()->location().beg_pos);
 
         Block* body_block =
             factory()->NewBlock(NULL, 3, false, RelocInfo::kNoPosition);
 
         {
@@ skipping 94 matching lines @@
         if (!is_destructuring) {
           expression = this->CheckAndRewriteReferenceExpression(
               expression, lhs_beg_pos, lhs_end_pos,
               MessageTemplate::kInvalidLhsInFor, kSyntaxError, CHECK_OK);
         }
 
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
-        Expression* enumerable = ParseExpression(true, CHECK_OK);
+        Expression* enumerable;
+        if (mode == ForEachStatement::ITERATE) {
+          ExpressionClassifier classifier;
+          enumerable = ParseAssignmentExpression(true, &classifier, CHECK_OK);
+          ParserTraits::RewriteNonPattern(enumerable, &classifier, CHECK_OK);

[adamk, 2016/01/20 00:35:57]

Same note here.

[mike3, 2016/01/20 17:55:40]

Acknowledged.

+        } else {
+          enumerable = ParseExpression(true, CHECK_OK);
+        }
+
         Expect(Token::RPAREN, CHECK_OK);
 
         // Make a block around the statement in case a lexical binding
         // is introduced, e.g. by a FunctionDeclaration.
         // This block must not use for_scope as its scope because if a
         // lexical binding is introduced which overlaps with the for-in/of,
         // expressions in head of the loop should actually have variables
         // resolved in the outer scope.
         Scope* body_scope = NewScope(for_scope, BLOCK_SCOPE);
         BlockState block_state(&scope_, body_scope);
@@ skipping 1931 matching lines @@
     auto class_literal = value->AsClassLiteral();
     if (class_literal->raw_name() == nullptr) {
       class_literal->set_raw_name(name);
     }
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8