Capturing for loop variables correctly

runtime/vm/parser.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 4345 matching lines @@
   ExpectSemicolon();
   AstNode* increment = NULL;
   intptr_t incr_pos = token_index_;
   LocalScope* incr_scope = current_block_->scope;
   if (CurrentToken() != Token::kRPAREN) {
     increment = ParseExprList();
   }
   ExpectToken(Token::kRPAREN);
   const bool parsing_loop_body =  true;
   SequenceNode* body = ParseNestedStatement(parsing_loop_body, NULL);
+
+  // Check whether any of the variables in the initializer part of
+  // the for statement are captured by a closure. If so, we insert a
+  // node that creates a new Context at the end of the loop body (but
+  // before the increment expression is evaluated).
+  for (int i = 0; i < init_scope->num_variables(); i++) {
+    if (init_scope->VariableAt(i)->is_captured() &&
+        (init_scope->VariableAt(i)->owner() == init_scope)) {
+      body->Add(new CloneContextNode(for_pos));
+      break;
+    }
+  }
   CloseBlock();
   return new ForNode(for_pos,
                      label,
                      NodeAsSequenceNode(init_pos, initializer, init_scope),
                      condition,
                      NodeAsSequenceNode(incr_pos, increment, incr_scope),
                      body);
 }
 
 
@@ skipping 2878 matching lines @@
 }
 
 
 void Parser::SkipNestedExpr() {
   const bool saved_mode = SetAllowFunctionLiterals(true);
   SkipExpr();
   SetAllowFunctionLiterals(saved_mode);
 }
 
 }  // namespace dart