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



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@98684 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index c6b6367..a18d5f1 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -778,6 +778,7 @@
                                         const LookupResult &Previous,
                                         Scope *S);
   void DiagnoseFunctionSpecifiers(Declarator& D);
+  void DiagnoseShadow(NamedDecl* D, const LookupResult& R);
   NamedDecl* ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
                                     QualType R, TypeSourceInfo *TInfo,
                                     LookupResult &Previous, bool &Redeclaration);