[SYCL] Deprecate Intel extension ctz function (#5333)

ctz function is added to the core SYCL specification.
Added a test for fixed issue (changed namespace for ctz function).

Author: IgorKharchikov

sycl/include/CL/sycl/builtins.hpp

@@ -734,8 +734,10 @@ detail::enable_if_t<detail::is_geninteger<T>::value, T> ctz(T x) __NOEXC {
 namespace ext {
 namespace intel {
 template <typename T>
-sycl::detail::enable_if_t<sycl::detail::is_geninteger<T>::value, T>
-ctz(T x) __NOEXC {
+__SYCL_DEPRECATED(
+    "'sycl::ext::intel::ctz' is deprecated, use 'sycl::ctz' instead")
+sycl::detail::enable_if_t<sycl::detail::is_geninteger<T>::value, T> ctz(
+    T x) __NOEXC {
   return sycl::ctz(x);
 }
 } // namespace intel

sycl/test/regression/ctz_namespace.cpp

@@ -0,0 +1,13 @@
+// RUN: %clangxx %fsycl-host-only -fsyntax-only -Xclang -verify -Xclang -verify-ignore-unexpected=note %s
+
+#include <sycl/sycl.hpp>
+
+int main() {
+
+  long long int a = -9223372034707292160ll;
+  long long int b = sycl::ctz(a);
+  // expected-warning@+1 {{'ctz<long long>' is deprecated: 'sycl::ext::intel::ctz' is deprecated, use 'sycl::ctz' instead}}
+  long long int c = sycl::ext::intel::ctz(a);
+
+  return 0;
+}