use cinttypes instead of inttypes.h header for C++ tests (#209)
diff --git a/tests/test_headers.c b/tests/test_headers.c
index 71f79bb..460a182 100644
--- a/tests/test_headers.c
+++ b/tests/test_headers.c
@@ -1,5 +1,5 @@
//
-// Copyright (c) 2020 The Khronos Group Inc.
+// Copyright (c) 2020-2022 The Khronos Group Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
@@ -14,7 +14,17 @@
// limitations under the License.
//
+/*
+Some versions of inttypes.h required defining the macro __STDC_FORMAT_MACROS to
+use the format macros for C++ compiles, but not all. To improve robustness we
+will use inttypes.h for C compiles and cinttypes for C++ compiles.
+*/
+#if defined(__cplusplus)
+#include <cinttypes>
+#else
#include <inttypes.h>
+#endif
+
#include <stdio.h>
#include "CL/cl.h"
