Implement a helper alias template for complex types (#1644)

Author: antonwolfy

dpnp/backend/kernels/dpnp_krnl_fft.cpp

@@ -414,7 +414,7 @@ DPCTLSyclEventRef dpnp_fft_fft_c(DPCTLSyclQueueRef q_ref,
                                  const size_t norm,
                                  const DPCTLEventVectorRef dep_event_vec_ref)
 {
-    static_assert(sycl::detail::is_complex<_DataType_output>::value,
+    static_assert(is_complex<_DataType_output>::value,
                   "Output data type must be a complex type.");
 
     DPCTLSyclEventRef event_ref = nullptr;
@@ -584,7 +584,7 @@ DPCTLSyclEventRef dpnp_fft_rfft_c(DPCTLSyclQueueRef q_ref,
                                   const size_t norm,
                                   const DPCTLEventVectorRef dep_event_vec_ref)
 {
-    static_assert(sycl::detail::is_complex<_DataType_output>::value,
+    static_assert(is_complex<_DataType_output>::value,
                   "Output data type must be a complex type.");
     DPCTLSyclEventRef event_ref = nullptr;
 

dpnp/backend/src/dpnp_fptr.hpp

@@ -219,6 +219,18 @@ template <typename _Tp>
 using dpnp_remove_cvref_t =
     typename std::remove_cv_t<typename std::remove_reference_t<_Tp>>;
 
+/**
+ * A helper alias template to return true value for complex types and false
+ * otherwise.
+ */
+template <typename _Tp>
+struct is_complex : public std::integral_constant<
+                        bool,
+                        std::is_same_v<_Tp, std::complex<float>> ||
+                            std::is_same_v<_Tp, std::complex<double>>>
+{
+};
+
 /**
  * @brief "<" comparison with complex types support.
  *