diff --git a/clang/include/clang/AST/ASTUnresolvedSet.h b/clang/include/clang/AST/ASTUnresolvedSet.h
--- a/clang/include/clang/AST/ASTUnresolvedSet.h
+++ b/clang/include/clang/AST/ASTUnresolvedSet.h
@@ -69,7 +69,12 @@
     return false;
   }
 
-  void erase(unsigned I) { Decls[I] = Decls.pop_back_val(); }
+  void erase(unsigned I) {
+    if (I == Decls.size() - 1)
+      Decls.pop_back();
+    else
+      Decls[I] = Decls.pop_back_val();
+  }
 
   void clear() { Decls.clear(); }
 
diff --git a/clang/test/SemaCXX/using-decl-templates.cpp b/clang/test/SemaCXX/using-decl-templates.cpp
--- a/clang/test/SemaCXX/using-decl-templates.cpp
+++ b/clang/test/SemaCXX/using-decl-templates.cpp
@@ -102,6 +102,28 @@
 };
 } // namespace DontDiagnoseInvalidTest
 
+namespace shadow_nested_operator {
+template <typename T>
+struct A {
+  struct Nested {};
+  operator Nested*() {return 0;};
+};
+
+template <typename T>
+struct B : A<T> {
+  using A<T>::operator typename A<T>::Nested*;
+  operator typename A<T>::Nested *() {
+    struct A<T> * thi = this;
+    return *thi;
+ };
+};
+
+int foo () {
+  struct B<int> b;
+  auto s = *b;
+}
+} // namespace shadow_nested_operator
+
 namespace func_templ {
 namespace sss {
 double foo(int, double);