--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp1y/pr84496.C	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,44 @@
+// PR c++/84496
+// { dg-do compile { target c++14 } }
+
+template <typename T, T n> struct C { static constexpr T D = n; };
+struct E : C<bool, false> {};
+template <typename> struct F : C<bool, false> {};
+template <typename T> T foo ();
+template <typename> struct H { typedef int G; };
+template <typename> class I;
+struct L;
+template <typename, typename> struct J;
+template <bool, bool, typename...> struct K;
+struct R {
+  template <typename M, typename... N>
+  static J<decltype (foo<M> () (foo<N>...)), L> o;
+};
+template <typename P, typename... Q> struct K<false, false, P, Q...> : R {
+  typedef decltype (o<P, Q...>) G;
+};
+template <typename P, typename... Q>
+struct D : K<E::D, F<typename H<P>::G>::D, P, Q...> {};
+template <typename P, typename... Q> struct I<P (Q...)> : D<P, Q...> {};
+template <typename> class function;
+template <typename S, typename... Q> struct function<S (Q...)> {
+  template <typename T, typename = typename I<T (Q...)>::G> struct C;
+  template <typename, typename> using U = int;
+  template <typename P, typename = U<int, void>, typename = U<C<P>, void>>
+  function (P);
+};
+template <typename S, typename... Q>
+template <typename P, typename, typename>
+function<S (Q...)>::function (P)
+{
+}
+void bar (function<void (int)>);
+
+void
+baz ()
+{
+  auto a = [] {
+    static int counter;
+    bar ([] (auto) { counter++; });
+  };
+}