Move std::common_type specialization to traits.hpp

and remove stale comments

Author: joeatodd

sycl/include/syclcompat/math.hpp

@@ -2302,30 +2302,3 @@ inline constexpr unsigned extend_vcompare4_add(AT a, BT b, unsigned c,
 }
 
 } // namespace syclcompat
-
-// Specialize std::common_type for bfloat16
-// Semantics here match bfloat16.hpp operator overloads (all mixed type math
-// ops return bfloat16)
-// TODO(syclcompat-lib-reviewers) Move this to bfloat extension
-namespace std {
-template <> struct common_type<sycl::ext::oneapi::bfloat16> {
-  using type = sycl::ext::oneapi::bfloat16;
-};
-
-template <>
-struct common_type<sycl::ext::oneapi::bfloat16, sycl::ext::oneapi::bfloat16> {
-  using type = sycl::ext::oneapi::bfloat16;
-};
-
-template <typename T> struct common_type<sycl::ext::oneapi::bfloat16, T> {
-  using type = sycl::ext::oneapi::bfloat16; // std::common_type_t<float, T>;  //
-                                            // sycl::ext::oneapi::bfloat16
-                                            // promotes to float
-};
-
-template <typename T> struct common_type<T, sycl::ext::oneapi::bfloat16> {
-  using type = sycl::ext::oneapi::bfloat16; // std::common_type_t<T, float>;  //
-                                            // sycl::ext::oneapi::bfloat16
-                                            // promotes to float
-};
-} // namespace std

sycl/include/syclcompat/traits.hpp

@@ -268,3 +268,26 @@ template <typename T>
 inline constexpr bool is_floating_point_v = is_floating_point<T>::value;
 
 } // namespace syclcompat
+
+// Specialize std::common_type for bfloat16
+// Semantics here match bfloat16.hpp operator overloads (all mixed type math
+// ops return bfloat16)
+// TODO(syclcompat-lib-reviewers) Move this to bfloat extension
+namespace std {
+template <> struct common_type<sycl::ext::oneapi::bfloat16> {
+  using type = sycl::ext::oneapi::bfloat16;
+};
+
+template <>
+struct common_type<sycl::ext::oneapi::bfloat16, sycl::ext::oneapi::bfloat16> {
+  using type = sycl::ext::oneapi::bfloat16;
+};
+
+template <typename T> struct common_type<sycl::ext::oneapi::bfloat16, T> {
+  using type = sycl::ext::oneapi::bfloat16;
+};
+
+template <typename T> struct common_type<T, sycl::ext::oneapi::bfloat16> {
+  using type = sycl::ext::oneapi::bfloat16;
+};
+} // namespace std