Instantiate unresolved using declarations.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@80366 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 4874c92..5d1c059 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -2160,8 +2160,9 @@
         << NNS << RD->getDeclName();
       return 0;
     }
-    
-    LookupContext = cast<RecordType>(Ty)->getDecl();
+
+    QualType BaseTy = Context.getCanonicalType(QualType(Ty, 0));
+    LookupContext = BaseTy->getAs<RecordType>()->getDecl();
   } else {
     // C++0x N2914 [namespace.udecl]p8:
     // A using-declaration for a class member shall be a member-declaration.