fix: add typename keyword to returnType declarations for clang

include/zRPCSupport.hpp

@@ -107,23 +107,23 @@ using isVoidReturn = std::is_void<typename callable_traits<F>::return_type>;
  * @tparam F Functor type to check the return type
  */
 template <typename F>
-using returnType = callable_traits<F>::return_type;
+using returnType = typename callable_traits<F>::return_type;
 
 /**
  * @brief Helper routine to get the number of arguments to F
  *
  * @tparam F Functor type to check number of arguments
  */
 template <typename F>
-using numArgs = callable_traits<F>::num_args;
+using numArgs = typename callable_traits<F>::num_args;
 
 /**
  * @brief Helper routine to get the types of arguments to F
  *
  * @tparam F Functor type to check types of arguments
  */
 template <typename F>
-using typeArgs = callable_traits<F>::type_args;
+using typeArgs = typename callable_traits<F>::type_args;
 
 /**
  * @brief Call the function using C++17 fold expression for the arguments
@@ -160,4 +160,4 @@ decltype(auto) call(F func, std::tuple<Args...> &args)
 }
 
 }  // namespace support
-}  // namespace zRPC
+}  // namespace zRPC