diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index c8c3815..0244d4c 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9300,7 +9300,7 @@
   // Static locals inherit dll attributes from their function.
   if (VD->isStaticLocal()) {
     if (FunctionDecl *FD =
-            dyn_cast<FunctionDecl>(VD->getParentFunctionOrMethod())) {
+            dyn_cast_or_null<FunctionDecl>(VD->getParentFunctionOrMethod())) {
       if (Attr *A = getDLLAttr(FD)) {
         auto *NewAttr = cast<InheritableAttr>(A->clone(getASTContext()));
         NewAttr->setInherited(true);
diff --git a/clang/test/SemaCXX/PR20705.cpp b/clang/test/SemaCXX/PR20705.cpp
new file mode 100644
index 0000000..be2676e
--- /dev/null
+++ b/clang/test/SemaCXX/PR20705.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify %s
+
+template <typename T>
+struct X {};
+auto b = []() {
+  struct S {
+    static typename X<decltype(int)>::type Run(){};
+    // expected-error@-1 4{{}}
+  };
+  return 5;
+}();
+
+template <typename T1, typename T2>
+class PC {
+};
+
+template <typename T>
+class P {
+  static typename PC<T, Invalid>::Type Foo();
+  // expected-error@-1 4{{}}
+};