--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/SemaTemplate/temp_arg_pack.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -verify %s
+
+namespace deduce_pack_non_pack {
+  template <typename...> class A;
+  template <typename> struct C {};
+  template <typename T> void g(C<A<T>>); // expected-note {{candidate template ignored: deduced type 'C<A<[...], (no argument)>>' of 1st parameter does not match adjusted type 'C<A<[...], int>>' of argument [with T = bool]}}
+  void h(C<A<bool, int>> &x) { g(x); } // expected-error {{no matching function}}
+}
+
+namespace pr39231 {
+  template<typename T, T ...V> struct integer_sequence {};
+
+  template <typename T, T... A, T... B>
+  int operator^(integer_sequence<T, A...> a, // expected-note {{deduced conflicting values for parameter 'A' (<1, 2, 3> vs. <4, 5, 6>)}}
+                integer_sequence<T, A...> b);
+
+  int v = integer_sequence<int, 1, 2, 3>{} ^ integer_sequence<int, 4, 5, 6>{}; // expected-error {{invalid operands}}
+
+  template <typename T, T... A, T... B>
+  integer_sequence<T, A + B...> operator+(integer_sequence<T, A...> a,
+                                          integer_sequence<T, B...> b);
+  integer_sequence<int, 5, 7, 9> w =
+      integer_sequence<int, 1, 2, 3>{} + integer_sequence<int, 4, 5, 6>{};
+}