fix use of c-array in has_clone trait

alib2std/src/extensions/type_traits.hpp

@@ -39,20 +39,18 @@ namespace ext {
 	template<class T>
 	struct has_clone {
 	private:
-		typedef char (&Yes)[1];
-		typedef char (&No)[2];
-
-		template<class U>
-		static Yes test(U * data, typename std::enable_if< std::is_pointer<decltype(data->clone())>::value>::type * = nullptr);
-		static No test(...);
+		template < class U >
+		static std::true_type test ( U * data, typename std::enable_if < std::is_pointer_v < decltype ( data->clone ( ) ) > >::type * = nullptr );
+		static std::false_type test ( ... );
 	public:
 		/**
 		 * \brief
 		 * True if the type decayed type T has clone method.
 		 */
-		static const bool value = sizeof(Yes) == sizeof(has_clone::test((typename std::decay<T>::type*)nullptr));
+		static const bool value = decltype ( has_clone::test ( std::declval < std::decay_t < T > * > ( ) ) )::value;
 	};
+
 	/**
 	 * \brief
 	 * Positive supports test implementation. The test is designed to detect call availability on callable F with parameters Ts ...