+/* Internal: needed by some of the following included headers */
+#ifdef __cplusplus
+# define __BT_UPCAST(_type, _p) static_cast<_type *>(static_cast<void *>(_p))
+# define __BT_UPCAST_CONST(_type, _p) static_cast<const _type *>(static_cast<const void *>(_p))
+#else
+# define __BT_UPCAST(_type, _p) ((_type *) (_p))
+# define __BT_UPCAST_CONST(_type, _p) ((const _type *) (_p))
+#endif
+