Small fix for STATIC_ASSERT.

src/checks.h

Index: src/checks.h
diff --git a/src/checks.h b/src/checks.h
index a560b2fb1524e2a207c6fe4c3a90a4f7eb9f3d60..2f359f6cd84efdd30f82ab6568a95657c6754edc 100644
--- a/src/checks.h
+++ b/src/checks.h
@@ -251,9 +251,9 @@ template <> class StaticAssertion<true> { };
 // actually causes each use to introduce a new defined type with a
 // name depending on the source line.
 template <int> class StaticAssertionHelper { };
-#define STATIC_CHECK(test)                                                  \
-  typedef                                                                   \
-    StaticAssertionHelper<sizeof(StaticAssertion<static_cast<bool>(test)>)> \
+#define STATIC_CHECK(test)                                                    \
+  typedef                                                                     \
+    StaticAssertionHelper<sizeof(StaticAssertion<static_cast<bool>((test))>)> \
     SEMI_STATIC_JOIN(__StaticAssertTypedef__, __LINE__)