1 files changed, 18 insertions, 0 deletions
diff --git a/clang/test/SemaTemplate/deduction.cpp b/clang/test/SemaTemplate/deduction.cpp
index 1f1c30a8b4a..7268912dd6c 100644
--- a/clang/test/SemaTemplate/deduction.cpp
+++ b/clang/test/SemaTemplate/deduction.cpp
@@ -546,3 +546,21 @@ namespace designators {
 
   static_assert(f({.a = 1, .b = 2}) == 3, ""); // expected-error {{no matching function}}
 }
+
+namespace nested_packs {
+  template<typename ...T, typename ...U> void f(T (*...f)(U...)); // expected-note {{deduced packs of different lengths for parameter 'U' (<> vs. <int>)}}
+  void g() { f(g); f(g, g); f(g, g, g); }
+  void h(int) { f(h); f(h, h); f(h, h, h); }
+  void i() { f(g, h); } // expected-error {{no matching function}}
+
+#if __cplusplus >= 201703L
+  template<auto ...A> struct Q {};
+  template<typename ...T, T ...A, T ...B> void q(Q<A...>, Q<B...>); // #q
+  void qt(Q<> q0, Q<1, 2> qii, Q<1, 2, 3> qiii) {
+    q(q0, q0);
+    q(qii, qii);
+    q(qii, qiii); // expected-error {{no match}} expected-note@#q {{deduced packs of different lengths for parameter 'T' (<int, int> vs. <int, int, int>)}}
+    q(q0, qiii); // expected-error {{no match}} expected-note@#q {{deduced packs of different lengths for parameter 'T' (<> vs. <int, int, int>)}}
+  }
+#endif
+}