Step #2/N of __label__ support: keep pushing LabelDecl forward,
making them be template instantiated in a more normal way and 
make them handle attributes like other decls.

This fixes the used/unused label handling stuff, making it use
the same infrastructure as other decls.

llvm-svn: 125771
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index bcec9d4..98555d9 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -629,6 +629,9 @@
   if (D->isUsed() || D->hasAttr<UnusedAttr>())
     return false;
 
+  if (isa<LabelDecl>(D))
+    return true;
+  
   // White-list anything that isn't a local variable.
   if (!isa<VarDecl>(D) || isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D) ||
       !D->getDeclContext()->isFunctionOrMethod())
@@ -675,12 +678,15 @@
   if (!ShouldDiagnoseUnusedDecl(D))
     return;
   
+  unsigned DiagID;
   if (isa<VarDecl>(D) && cast<VarDecl>(D)->isExceptionVariable())
-    Diag(D->getLocation(), diag::warn_unused_exception_param)
-    << D->getDeclName();
+    DiagID = diag::warn_unused_exception_param;
+  else if (isa<LabelDecl>(D))
+    DiagID = diag::warn_unused_label;
   else
-    Diag(D->getLocation(), diag::warn_unused_variable) 
-    << D->getDeclName();
+    DiagID = diag::warn_unused_variable;
+
+  Diag(D->getLocation(), DiagID) << D->getDeclName();
 }
 
 void Sema::ActOnPopScope(SourceLocation Loc, Scope *S) {