Fix another assert related to using decls.

llvm-svn: 74262
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 4d25f5b..0d5c545 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -212,6 +212,9 @@
 
     case LResult::Found: {
       NamedDecl *ND = I->getAsDecl();
+      if (UsingDecl *UD = dyn_cast<UsingDecl>(ND))
+        ND = UD->getTargetDecl();
+        
       if (TagDecl *TD = dyn_cast<TagDecl>(ND)) {
         TagFound = Context.getCanonicalDecl(TD);
         TagNames += FoundDecls.insert(TagFound)?  1 : 0;