In background compilation make a copy of Field in order to freeze its state

runtime/vm/ast.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_AST_H_
 #define VM_AST_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
@@ skipping 132 matching lines @@
 
   // Analyzes an expression to determine whether it is a compile time
   // constant or not. Returns NULL if the expression is not a compile time
   // constant. Otherwise, the return value is an approximation of the
   // actual value of the const expression. The type of the returned value
   // corresponds to the type of the const expression and is either
   // Number, Integer, String, Bool, or anything else (not a subtype of
   // the former).
   virtual const Instance* EvalConstExpr() const { return NULL; }
 
+  // Return ZoneHandle of a cloned 'value' when in background compilation or
+  // when testing. Otherwise return 'value' itself.
+  static const Field* MayCloneField(const Field& value);
+
  protected:
   friend class ParsedFunction;
 
  private:
   const TokenPosition token_pos_;
   DISALLOW_COPY_AND_ASSIGN(AstNode);
 };
 
 
 class AwaitNode : public AstNode {
@@ skipping 1071 matching lines @@
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(StoreLocalNode);
 };
 
 
 class LoadInstanceFieldNode : public AstNode {
  public:
   LoadInstanceFieldNode(TokenPosition token_pos,
                         AstNode* instance,
                         const Field& field)
-      : AstNode(token_pos), instance_(instance), field_(field) {
+      : AstNode(token_pos), instance_(instance),
+        field_(*MayCloneField(field)) {
     ASSERT(instance_ != NULL);
     ASSERT(field_.IsZoneHandle());
   }
 
   AstNode* instance() const { return instance_; }
   const Field& field() const { return field_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
     instance()->Visit(visitor);
   }
 
   DECLARE_COMMON_NODE_FUNCTIONS(LoadInstanceFieldNode);
 
  private:
   AstNode* instance_;
   const Field& field_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(LoadInstanceFieldNode);
 };
 
 
 class StoreInstanceFieldNode : public AstNode {
  public:
   StoreInstanceFieldNode(TokenPosition token_pos,
                          AstNode* instance,
                          const Field& field,
                          AstNode* value)
       : AstNode(token_pos),
         instance_(instance),
-        field_(field),
+        field_(*MayCloneField(field)),
         value_(value) {
     ASSERT(instance_ != NULL);
     ASSERT(field_.IsZoneHandle());
     ASSERT(value_ != NULL);
   }
 
   AstNode* instance() const { return instance_; }
   const Field& field() const { return field_; }
   AstNode* value() const { return value_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
     instance()->Visit(visitor);
     value()->Visit(visitor);
   }
 
   DECLARE_COMMON_NODE_FUNCTIONS(StoreInstanceFieldNode);
 
  private:
   AstNode* instance_;
   const Field& field_;
   AstNode* value_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(StoreInstanceFieldNode);
 };
 
 
 class LoadStaticFieldNode : public AstNode {
  public:
   LoadStaticFieldNode(TokenPosition token_pos, const Field& field)
-      : AstNode(token_pos), field_(field), is_deferred_reference_(false) {
+      : AstNode(token_pos),
+        field_(*MayCloneField(field)),
+        is_deferred_reference_(false) {
     ASSERT(field_.IsZoneHandle());
   }
 
   const Field& field() const { return field_; }
   void set_is_deferred(bool value) { is_deferred_reference_ = value; }
   bool is_deferred_reference() const { return is_deferred_reference_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const { }
 
   virtual AstNode* MakeAssignmentNode(AstNode* rhs);
@@ skipping 17 matching lines @@
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(LoadStaticFieldNode);
 };
 
 
 class StoreStaticFieldNode : public AstNode {
  public:
   StoreStaticFieldNode(TokenPosition token_pos,
                        const Field& field,
                        AstNode* value)
-      : AstNode(token_pos), field_(field), value_(value) {
+      : AstNode(token_pos),
+        field_(*MayCloneField(field)),
+        value_(value) {
     ASSERT(field_.IsZoneHandle());
     ASSERT(value_ != NULL);
   }
 
   const Field& field() const { return field_; }
   AstNode* value() const { return value_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
     value()->Visit(visitor);
   }
@@ skipping 201 matching lines @@
   AstNode* value_;
   const bool is_conditional_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(InstanceSetterNode);
 };
 
 
 class InitStaticFieldNode : public AstNode {
  public:
   InitStaticFieldNode(TokenPosition token_pos, const Field& field)
-      : AstNode(token_pos), field_(field) {
+      : AstNode(token_pos),
+        field_(*MayCloneField(field)) {
     ASSERT(field_.IsZoneHandle());
   }
 
   const Field& field() const { return field_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const { }
 
   DECLARE_COMMON_NODE_FUNCTIONS(InitStaticFieldNode);
 
  private:
@@ skipping 460 matching lines @@
   const intptr_t try_index_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(InlinedFinallyNode);
 };
 
 }  // namespace dart
 
 #undef DECLARE_COMMON_NODE_FUNCTIONS
 
 #endif  // VM_AST_H_