Implement -Wshadow.  Based on a patch by Mike M.!

llvm-svn: 98684
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index f568d1c..6c9a45e 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -430,7 +430,10 @@
   for (; I!=End; ++I)
     QualName += *I + "::";
 
-  QualName += getNameAsString();
+  if (getDeclName())
+    QualName += getNameAsString();
+  else
+    QualName += "<anonymous>";
 
   return QualName;
 }