Bug 944176: Implement move construction and move assignment for mozilla::Scoped derivatives. r=waldo

mfbt/Scoped.h

@@ -52,8 +52,10 @@
  * the scope, graphics contexts, etc.
  */
 
+#include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/GuardObjects.h"
+#include "mozilla/Move.h"
 #include "mozilla/NullPtr.h"
 
 namespace mozilla {
@@ -83,12 +85,23 @@ class Scoped
     {
       MOZ_GUARD_OBJECT_NOTIFIER_INIT;
     }
+
     explicit Scoped(const Resource& v
                     MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
       : value(v)
     {
       MOZ_GUARD_OBJECT_NOTIFIER_INIT;
     }
+
+    /* Move constructor. */
+    explicit Scoped(Scoped&& v
+                    MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+      : value(Move(v.value))
+    {
+      MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+      v.value = Traits::empty();
+    }
+
     ~Scoped() {
       Traits::release(value);
     }
@@ -146,6 +159,14 @@ class Scoped
       return *this;
     }
 
+    /* Move assignment operator. */
+    Scoped& operator=(Scoped&& rhs) {
+      MOZ_ASSERT(&rhs != this, "self-move-assignment not allowed");
+      this->~Scoped();
+      new(this) Scoped(Move(rhs));
+      return *this;
+    }
+
   private:
     explicit Scoped(const Scoped& value) MOZ_DELETE;
     Scoped& operator=(const Scoped& value) MOZ_DELETE;
@@ -169,20 +190,30 @@ struct name : public mozilla::Scoped<Traits<Type> >            \
 {                                                              \
     typedef mozilla::Scoped<Traits<Type> > Super;              \
     typedef typename Super::Resource Resource;                 \
-    name& operator=(Resource ptr) {                            \
-      Super::operator=(ptr);                                   \
+    name& operator=(Resource rhs) {                            \
+      Super::operator=(rhs);                                   \
+      return *this;                                            \
+    }                                                          \
+    name& operator=(name&& rhs) {                              \
+      Super::operator=(Move(rhs));                             \
       return *this;                                            \
     }                                                          \
     explicit name(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM)        \
       : Super(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_TO_PARENT)  \
     {}                                                         \
-    explicit name(Resource ptr                                 \
+    explicit name(Resource rhs                                 \
                   MOZ_GUARD_OBJECT_NOTIFIER_PARAM)             \
-      : Super(ptr MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)   \
+      : Super(rhs                                              \
+              MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)       \
+    {}                                                         \
+    explicit name(name&& rhs                                   \
+                  MOZ_GUARD_OBJECT_NOTIFIER_PARAM)             \
+      : Super(Move(rhs)                                        \
+              MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)       \
     {}                                                         \
   private:                                                     \
-    explicit name(name& source) MOZ_DELETE;                    \
-    name& operator=(name& source) MOZ_DELETE;                  \
+    explicit name(name&) MOZ_DELETE;                           \
+    name& operator=(name&) MOZ_DELETE;                         \
 };
 
 /*