Fix windows compfail for bfloat16 isnan test (intel#1520)

Signed-off-by: jinge90 <ge.jin@intel.com>

Author: jinge90

SYCL/BFloat16/bfloat16_builtins.cpp

@@ -222,6 +222,26 @@ bool check(bool a, bool b) { return (a == b); }
   assert(err == 0);                                                            \
   assert(std::isnan(check_nan));
 
+// The intention to introduce a proxy function for isnan is to bypass a compfail
+// on Win64 platform. If we simply pass 'isnan' to testing macro, compiler will
+// report 'ambiguous call' error. This is becayse MSVC header correct_math.h
+// includes an isnan definition too. In order to bypass this without modifying
+// current test infrastructure, we add proxy function for 'isnan' and uses full
+// name to avoid amibiguity.
+bool isnan_test_proxy(sycl::ext::oneapi::bfloat16 x) {
+  return sycl::ext::oneapi::experimental::isnan(x);
+}
+template <size_t N>
+sycl::marray<bool, N>
+isnan_test_proxy(sycl::marray<sycl::ext::oneapi::bfloat16, N> x) {
+  return sycl::ext::oneapi::experimental::isnan(x);
+}
+bool isnan_test_proxy(float x) { return sycl::isnan(x); }
+template <size_t N>
+sycl::marray<bool, N> isnan_test_proxy(sycl::marray<float, N> x) {
+  return sycl::isnan(x);
+}
+
 int main() {
   queue q;
 
@@ -246,7 +266,7 @@ int main() {
 
     // Insert NAN value in a to test isnan
     a[0] = a[N - 1] = NAN;
-    TEST_BUILTIN_1(isnan, bool);
+    TEST_BUILTIN_1(isnan_test_proxy, bool);
   }
   return 0;
 }