In C++11, promote access declaration diagnostic from warning to error. There
doesn't seem to be any value in even adding a -W flag for this.

llvm-svn: 183882
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index be198ad..a4549fb 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -6742,8 +6742,10 @@
   // diagnostics.
   if (!HasUsingKeyword) {
     UsingLoc = Name.getLocStart();
-    
-    Diag(UsingLoc, diag::warn_access_decl_deprecated)
+
+    Diag(UsingLoc,
+         getLangOpts().CPlusPlus11 ? diag::err_access_decl
+                                   : diag::warn_access_decl_deprecated)
       << FixItHint::CreateInsertion(SS.getRange().getBegin(), "using ");
   }