Fix cppcheck warnings

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: If5d808b9cb3bc733e7e21d546247d745ac5e1bf8
diff --git a/src/tupleref.hpp b/src/tupleref.hpp
index 3954d46..dafd4f9 100644
--- a/src/tupleref.hpp
+++ b/src/tupleref.hpp
@@ -39,7 +39,7 @@
 template <size_t size, typename T, typename U>
 struct TupleOfRefsLess<size, size, T, U>
 {
-    static constexpr bool compare(const T& l, const U& r)
+    static constexpr bool compare(const T& /* l */, const U& /* r */)
     {
         return false;
     }