Index: lib/Sema/SemaCXXScopeSpec.cpp
===================================================================
--- lib/Sema/SemaCXXScopeSpec.cpp
+++ lib/Sema/SemaCXXScopeSpec.cpp
@@ -1054,7 +1054,12 @@
   // it is a complete declaration context.
   if (!DC->isDependentContext() && RequireCompleteDeclContext(SS, DC))
     return true;
-    
+
+  // Don't enter a declarator context when the current context is an Objective-C
+  // declaration as we might no be able to restore it when exiting the scope.
+  if (isa<ObjCContainerDecl>(CurContext) || isa<ObjCMethodDecl>(CurContext))
+    return true;
+
   EnterDeclaratorContext(S, DC);
 
   // Rebuild the nested name specifier for the new scope.
Index: test/SemaObjCXX/crash.mm
===================================================================
--- test/SemaObjCXX/crash.mm
+++ test/SemaObjCXX/crash.mm
@@ -25,3 +25,17 @@
 // expected-warning@-2 {{variadic templates are a C++11 extension}}
 #endif
 @end
+
+// rdar://20560175
+
+struct OuterType {
+  typedef int InnerType;
+};
+
+@protocol InvalidProperty
+@property (nonatomic) (OuterType::InnerType) invalidTypeParens;
+// expected-error@-1 {{type name requires a specifier or qualifier}}
+// expected-error@-2 {{expected ';' at end of declaration list}}
+// expected-error@-3 {{C++ requires a type specifier for all declarations}}
+// expected-error@-4 {{cannot declare variable inside @interface or @protocol}}
+@end