test/support/utils_sycl_defs.h - fix compile error: incomplete type 'TestUtils::TestPolicyName' named in nested name specifier

	Building CXX object test/CMakeFiles/header_inclusion_order_async_0.pass.dir/general/header_inclusion_order_async_0.pass.cpp.o
	In file included from /test/general/header_inclusion_order_async_0.pass.cpp:19:
	In file included from /test/support/utils.h:47:
	In file included from /test/support/utils_test_base.h:25:
	In file included from /test/support/utils_invoke.h:25:
	/test/support/utils_sycl_defs.h:53:1: error: incomplete type 'TestUtils::TestPolicyName' named in nested name specifier
	   53 | using new_kernel_name = unique_kernel_name<typename std::decay_t<Policy>::kernel_name, idx>;
		  | ^~~~~
	/test/support/utils_invoke.h:132:39: note: in instantiation of template type alias 'new_kernel_name' requested here
	  132 |     using _NewKernelName = TestUtils::new_kernel_name<PolicyName, call_id>;
		  |                                       ^
	/test/general/header_inclusion_order_async_0.pass.cpp:26:30: note: in instantiation of function template specialization 'TestUtils::get_dpcpp_test_policy<0, TestUtils::TestPolicyName>' requested here
	   26 |     auto policy = TestUtils::get_dpcpp_test_policy();
		  |                              ^
	/test/support/utils_invoke.h:126:8: note: forward declaration of 'TestUtils::TestPolicyName'
	  126 | struct TestPolicyName;
		  |        ^
	1 error generated.

Author: SergeyKopienko

test/support/utils_sycl_defs.h

@@ -49,8 +49,32 @@ uniq_kernel_index()
 template <typename Op, std::size_t CallNumber>
 struct unique_kernel_name;
 
+template <typename T, typename = std::void_t<>>
+struct has_kernel_name : std::false_type
+{
+};
+
+template <typename T>
+struct has_kernel_name<T, std::void_t<typename T::kernel_name>> : std::true_type
+{
+};
+
+template <typename Policy, std::size_t CallNumber, typename = void>
+struct new_kernel_name_impl
+{
+    static_assert(!has_kernel_name<std::decay_t<Policy>>::value);
+    using type = unique_kernel_name<std::decay_t<Policy>, CallNumber>;
+};
+
+template <typename Policy, std::size_t CallNumber>
+struct new_kernel_name_impl<Policy, CallNumber, std::enable_if_t<has_kernel_name<std::decay_t<Policy>>::value>>
+{
+    static_assert(has_kernel_name<std::decay_t<Policy>>::value);
+    using type = unique_kernel_name<typename std::decay_t<Policy>::kernel_name, CallNumber>;
+};
+
 template <typename Policy, std::size_t idx>
-using new_kernel_name = unique_kernel_name<typename std::decay_t<Policy>::kernel_name, idx>;
+using new_kernel_name = typename new_kernel_name_impl<Policy, idx>::type;
 
 } /* namespace TestUtils */