- Ensure that BaseIsolate is only used to break the header include cycles.

runtime/vm/allocation.h

 // Copyright (c) 2013, 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_ALLOCATION_H_
 #define VM_ALLOCATION_H_
 
 #include "platform/assert.h"
 #include "vm/base_isolate.h"
 #include "vm/globals.h"
@@ skipping 18 matching lines @@
 };
 
 
 // Stack resources subclass from this base class. The VM will ensure that the
 // destructors of these objects are called before the stack is unwound past the
 // objects location on the stack. Use stack resource objects if objects
 // need to be destroyed even in the case of exceptions when a Longjump is done
 // to a stack frame above the frame where these objects were allocated.
 class StackResource {
  public:
-  explicit StackResource(BaseIsolate* isolate)
-      : isolate_(isolate), previous_(NULL) {
+  explicit StackResource(Isolate* isolate)
+      : isolate_(reinterpret_cast<BaseIsolate*>(isolate)), previous_(NULL) {

[koda, 2014/05/05 21:51:28]

Use implicit_cast from platform/globals.h.

     // We can only have longjumps and exceptions when there is a current
     // isolate.  If there is no current isolate, we don't need to
     // protect this case.
-    if (isolate != NULL) {
-      previous_ = isolate->top_resource();
-      isolate->set_top_resource(this);
+    if (isolate_ != NULL) {
+      previous_ = isolate_->top_resource();
+      isolate_->set_top_resource(this);
     }
   }
 
   virtual ~StackResource() {
-    if (isolate() != NULL) {
-      StackResource* top = isolate()->top_resource();
+    if (isolate_ != NULL) {
+      StackResource* top = isolate_->top_resource();
       ASSERT(top == this);
-      isolate()->set_top_resource(previous_);
+      isolate_->set_top_resource(previous_);
     }
 #if defined(DEBUG)
-    if (isolate() != NULL) {
-      BaseIsolate::AssertCurrent(isolate());
+    if (isolate_ != NULL) {
+      BaseIsolate::AssertCurrent(isolate_);
     }
 #endif
   }
 
-  BaseIsolate* isolate() const { return isolate_; }
+  // We can only create StackResources with Isolates, so provide the original
+  // isolate to the subclasses. The only reason we have a BaseIsolate in the
+  // StackResource is to break the header include cycles.
+  Isolate* isolate() const { return reinterpret_cast<Isolate*>(isolate_); }

[koda, 2014/05/05 21:51:28]

Use down_cast.

 
  private:
   BaseIsolate* const isolate_;  // Current isolate for this stack resource.
   StackResource* previous_;
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(StackResource);
 };
 
 
@@ skipping 29 matching lines @@
   // deallocated by invoking DeleteAll() on the zone they live in.
   void operator delete(void* pointer) { UNREACHABLE(); }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ZoneAllocated);
 };
 
 }  // namespace dart
 
 #endif  // VM_ALLOCATION_H_