--- /dev/null
+// PR c++/56611
+// { dg-do compile { target c++11 } }
+
+template<class T> struct remove_reference { typedef T type; };
+template<class T> struct remove_reference<T&> { typedef T type; };
+template<class T> T declval() { return T(); }
+
+int f(int, int){return 0;}
+struct Func{};
+
+template<class... Args> struct result1
+{
+ typedef decltype(f(declval<typename remove_reference<Args>::type>()...)) type;
+};
+
+template<class... Args> using result2
+= decltype(f(declval<typename remove_reference<Args>::type>()...));
+
+template<class Sig> struct R;
+template<class This, class... Args> struct R< This(Args...) >
+{
+ typedef result2<Args...> type;
+};
+
+typedef R< Func(int, int) >::type R_type;