Index: test/support/test_macros.h
===================================================================
--- test/support/test_macros.h
+++ test/support/test_macros.h
@@ -209,7 +209,8 @@
 #include <intrin.h>
 template <class Tp>
 inline void DoNotOptimize(Tp const& value) {
-  const volatile void* volatile = __builtin_addressof(value);
+  const volatile void* volatile unused = __builtin_addressof(value);
+  static_cast<void>(unused);
   _ReadWriteBarrier();
 }
 #endif