1 files changed, 22 insertions, 1 deletions
diff --git a/test/SemaTemplate/dependent-type-identity.cpp b/test/SemaTemplate/dependent-type-identity.cpp
index a796834..5b9da5d 100644
--- a/test/SemaTemplate/dependent-type-identity.cpp
+++ b/test/SemaTemplate/dependent-type-identity.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
 
 // This test concerns the identity of dependent types within the
 // canonical type system. This corresponds to C++ [temp.type], which
@@ -122,3 +122,24 @@ namespace PR18275 {
   template struct A<int>;
   template struct A<int[1]>;
 }
+
+namespace PR21289 {
+  template<typename T> using X = int;
+  template<typename T, decltype(sizeof(0))> using Y = int;
+  template<typename ...Ts> struct S {};
+  template<typename ...Ts> void f() {
+    // This is a dependent type. It is *not* S<int>, even though it canonically
+    // contains no template parameters.
+    using Type = S<X<Ts>...>;
+    Type s;
+    using Type = S<int, int, int>;
+  }
+  void g() { f<void, void, void>(); }
+
+  template<typename ...Ts> void h(S<int>) {}
+  // Pending a core issue, it's not clear if these are redeclarations, but they
+  // are probably intended to be... even though substitution can succeed for one
+  // of them but fail for the other!
+  template<typename ...Ts> void h(S<X<Ts>...>) {} // expected-note {{previous}}
+  template<typename ...Ts> void h(S<Y<Ts, sizeof(Ts)>...>) {} // expected-error {{redefinition}}
+}