diff --git a/js/public/RootingAPI.h b/js/public/RootingAPI.h
index 528a15ae1f18..81a9f3020b6f 100644
--- a/js/public/RootingAPI.h
+++ b/js/public/RootingAPI.h
@@ -237,7 +237,7 @@ AssertGCThingIsNotAnObjectSubclass(js::gc::Cell* cell) {}
  * Type T must be a public GC pointer type.
  */
 template <typename T>
-class Heap : public js::HeapBase<T, Heap<T>>
+class MOZ_NON_MEMMOVABLE Heap : public js::HeapBase<T, Heap<T>>
 {
     // Please note: this can actually also be used by nsXBLMaybeCompiled<T>, for legacy reasons.
     static_assert(js::IsHeapConstructibleType<T>::value,
@@ -1173,6 +1173,14 @@ class JS_PUBLIC_API(ObjectPtr)
 
     explicit ObjectPtr(JSObject* obj) : value(obj) {}
 
+    ObjectPtr(const ObjectPtr& other) : value(other.value) {}
+
+    ObjectPtr(ObjectPtr&& other)
+      : value(other.value)
+    {
+        other.value = nullptr;
+    }
+
     /* Always call finalize before the destructor. */
     ~ObjectPtr() { MOZ_ASSERT(!value); }
 
diff --git a/js/src/gc/Barrier.h b/js/src/gc/Barrier.h
index b0486f94949d..dc6af50bb079 100644
--- a/js/src/gc/Barrier.h
+++ b/js/src/gc/Barrier.h
@@ -318,8 +318,11 @@ struct InternalBarrierMethods<jsid>
 };
 
 // Base class of all barrier types.
+//
+// This is marked non-memmovable since post barriers added by derived classes
+// can add pointers to class instances to the store buffer.
 template <typename T>
-class BarrieredBase
+class MOZ_NON_MEMMOVABLE BarrieredBase
 {
   protected:
     // BarrieredBase is not directly instantiable.
diff --git a/xpcom/ds/nsTArray.h b/xpcom/ds/nsTArray.h
index 424a50ba421e..4e9b57126bfb 100644
--- a/xpcom/ds/nsTArray.h
+++ b/xpcom/ds/nsTArray.h
@@ -37,6 +37,7 @@
 namespace JS {
 template<class T>
 class Heap;
+class ObjectPtr;
 } /* namespace JS */
 
 class nsRegion;
@@ -708,7 +709,7 @@ struct nsTArray_CopyWithConstructors
 template<class E>
 struct MOZ_NEEDS_MEMMOVABLE_TYPE nsTArray_CopyChooser
 {
-  typedef nsTArray_CopyWithMemutils Type;
+  using Type = nsTArray_CopyWithMemutils;
 };
 
 //
@@ -719,14 +720,18 @@ struct MOZ_NEEDS_MEMMOVABLE_TYPE nsTArray_CopyChooser
   template<>                                            \
   struct nsTArray_CopyChooser<T>                        \
   {                                                     \
-    typedef nsTArray_CopyWithConstructors<T> Type;      \
+    using Type = nsTArray_CopyWithConstructors<T>;      \
   };
 
-template<class E>
-struct nsTArray_CopyChooser<JS::Heap<E>>
-{
-  typedef nsTArray_CopyWithConstructors<JS::Heap<E>> Type;
-};
+#define DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(T)   \
+  template<typename S>                                  \
+  struct nsTArray_CopyChooser<T<S>>                     \
+  {                                                     \
+    using Type = nsTArray_CopyWithConstructors<T<S>>;   \
+  };
+
+DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(JS::Heap)
+DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(std::function)
 
 DECLARE_USE_COPY_CONSTRUCTORS(nsRegion)
 DECLARE_USE_COPY_CONSTRUCTORS(nsIntRegion)
@@ -740,13 +745,7 @@ DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::SerializedStructuredClone
 DECLARE_USE_COPY_CONSTRUCTORS(JSStructuredCloneData)
 DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::MessagePortMessage)
 DECLARE_USE_COPY_CONSTRUCTORS(mozilla::SourceBufferTask)
-
-template<typename T>
-struct nsTArray_CopyChooser<std::function<T>>
-{
-  typedef nsTArray_CopyWithConstructors<std::function<T>> Type;
-};
-
+DECLARE_USE_COPY_CONSTRUCTORS(JS::ObjectPtr)
 
 //
 // Base class for nsTArray_Impl that is templated on element type and derived