Add comment in static assert.

Author: uditagarwal97

sycl/include/sycl/vector.hpp

@@ -802,7 +802,9 @@ template <typename Type, int NumElements> class vec {
         std::is_same_v<DataT, bfloat16> && std::is_same_v<convertT, float>;
     if constexpr (isFloatToBF16Conv || isBF16ToFloatConv) {
       static_assert(roundingMode == rounding_mode::automatic ||
-                    roundingMode == rounding_mode::rte);
+                    roundingMode == rounding_mode::rte,
+                    "Currently, we only supoort round-to-even rounding mode
+                      for Bfloat16 <--> float conversion.");
     }
 
     using T = vec_data_t<DataT>;

sycl/include/sycl/vector_preview.hpp

@@ -434,7 +434,9 @@ class vec : public detail::vec_arith<DataT, NumElements> {
           std::is_same_v<DataT, bfloat16> && std::is_same_v<convertT, float>;
       if constexpr (isFloatToBF16Conv || isBF16ToFloatConv) {
         static_assert(roundingMode == rounding_mode::automatic ||
-                      roundingMode == rounding_mode::rte);
+                    roundingMode == rounding_mode::rte,
+                    "Currently, we only supoort round-to-even rounding mode
+                      for Bfloat16 <--> float conversion.");
       }
     }