More improvements to namespace aliases. We now support everything except aliases in using directives.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67966 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index a879989..5395869 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -144,6 +144,10 @@
         return NestedNameSpecifier::Create(Context, Prefix, false, 
                                            T.getTypePtr());
     }
+    
+    if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD))
+      return NestedNameSpecifier::Create(Context, Prefix,
+                                         Alias->getNamespace());
 
     // Fall through to produce an error: we found something that isn't
     // a class or a namespace.