mark type_info_of param as [[maybe_unused]]

Summary: Mark the param to `folly::type_info_of` param as `[[maybe_unused]]` since, when RTTI is unavailable, it is unused.

Differential Revision: D26537864

fbshipit-source-id: 3fd0a1bb0d3ecbbcdc5e07f153e321a0b8537478

folly/lang/TypeInfo.h

@@ -18,6 +18,7 @@
 
 #include <typeinfo>
 
+#include <folly/CppAttributes.h>
 #include <folly/Portability.h>
 
 //  FOLLY_TYPE_INFO_OF
@@ -48,7 +49,8 @@ FOLLY_ALWAYS_INLINE static std::type_info const* type_info_of() {
 //
 //  This overload works on the dynamic type of the non-template parameter.
 template <typename T>
-FOLLY_ALWAYS_INLINE static std::type_info const* type_info_of(T const& t) {
+FOLLY_ALWAYS_INLINE static std::type_info const* type_info_of(
+    FOLLY_MAYBE_UNUSED T const& t) {
   return FOLLY_TYPE_INFO_OF(t);
 }