[SYCL][NFC] Remove unused detail::vector_size (#15660)

Author: aelovikov-intel

sycl/include/sycl/detail/type_traits.hpp

@@ -124,15 +124,6 @@ template <typename T, typename R> struct copy_cv_qualifiers;
 template <typename T, typename R>
 using copy_cv_qualifiers_t = typename copy_cv_qualifiers<T, R>::type;
 
-// vector_size
-// scalars are interpreted as a vector of 1 length.
-template <typename T> struct vector_size_impl : std::integral_constant<int, 1> {};
-template <typename T, int N>
-struct vector_size_impl<vec<T, N>> : std::integral_constant<int, N> {};
-template <typename T>
-struct vector_size
-    : vector_size_impl<std::remove_cv_t<std::remove_reference_t<T>>> {};
-
 // vector_element
 template <typename T> struct vector_element_impl;
 template <typename T>

sycl/test/type_traits/type_traits.cpp

@@ -67,11 +67,6 @@ void test_remove_pointer_t() {
                 "");
 }
 
-template <typename T, int Checked, bool Expected = true>
-void test_vector_size() {
-  static_assert((d::vector_size<T>::value == Checked) == Expected, "");
-}
-
 int main() {
   test_is_pointer<int *>();
   test_is_pointer<float *>();
@@ -155,14 +150,6 @@ int main() {
   test_make_unsigned_t<s::uint2, s::uint2>();
   test_make_unsigned_t<const s::uint2, const s::uint2>();
 
-  test_vector_size<int, 1>();
-  test_vector_size<float, 1>();
-  test_vector_size<double, 1>();
-  test_vector_size<s::int2, 2>();
-  test_vector_size<s::float3, 3>();
-  test_vector_size<s::double4, 4>();
-  test_vector_size<s::vec<int, 1>, 1>();
-
 #ifdef __SYCL_DEVICE_ONLY__
   static_assert(
       std::is_same_v<