Add casting move constructor

include/rcp.h

@@ -31,6 +31,8 @@
 template <typename T>
 class rcp
 {
+    template <typename U> friend class rcp;
+
 private:
     T * ptr = nullptr;
 
@@ -100,7 +102,7 @@ public:
 
     /* Upcasting constructor: allows rcp<Derived> -> rcp<Base> */
     template <typename U>
-    rcp(const rcp<U> & other) : ptr(static_cast<T *>(other.get_raw()))
+    rcp(const rcp<U> & other) : ptr(static_cast<T *>(other.ptr))
     {
         static_assert(std::is_base_of<T, U>::value, "rcp: implicit cast must be an upcast");
         if (ptr)
@@ -109,6 +111,13 @@ public:
         }
     }
 
+    template <typename U>
+    rcp(rcp<U> && other) : ptr(static_cast<T *>(other.ptr))
+    {
+        static_assert(std::is_base_of<T, U>::value, "rcp: implicit cast must be an upcast");
+        other.ptr = nullptr;
+    }
+
     T * get_raw() const
     {
         return ptr;