[SYCL] Fix underlying type for std::byte when multi_ptr is used (#4705)

Signed-off-by: mdimakov <[email protected]>

Author: maximdimakov

sycl/include/CL/sycl/detail/generic_type_traits.hpp

@@ -429,13 +429,23 @@ struct select_cl_vector_or_scalar<
 template <typename T, typename Enable = void>
 struct select_cl_mptr_or_vector_or_scalar;
 
+// this struct helps to use std::uint8_t instead of std::byte,
+// which is not supported on device
+template <typename T> struct TypeHelper { using RetType = T; };
+
+#if __cplusplus >= 201703L
+template <> struct TypeHelper<std::byte> { using RetType = std::uint8_t; };
+#endif
+
+template <typename T> using type_helper = typename TypeHelper<T>::RetType;
+
 template <typename T>
 struct select_cl_mptr_or_vector_or_scalar<
     T, typename detail::enable_if_t<is_genptr<T>::value &&
                                     !std::is_pointer<T>::value>> {
-  using type = multi_ptr<
-      typename select_cl_vector_or_scalar<typename T::element_type>::type,
-      T::address_space>;
+  using type = multi_ptr<typename select_cl_vector_or_scalar<
+                             type_helper<typename T::element_type>>::type,
+                         T::address_space>;
 };
 
 template <typename T>