Implicitly assume that a ObjC category to an unavailable interface is also unavailable;
only give an 'unavailable' error on the @implementation of the category. rdar://10234078

llvm-svn: 141335
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 4a4862b..3692f44 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9663,3 +9663,12 @@
 Decl *Sema::getObjCDeclContext() const {
   return (dyn_cast_or_null<ObjCContainerDecl>(CurContext));
 }
+
+AvailabilityResult Sema::getCurContextAvailability() const {
+  const Decl *D = cast<Decl>(getCurLexicalContext());
+  // A category implicitly has the availability of the interface.
+  if (const ObjCCategoryDecl *CatD = dyn_cast<ObjCCategoryDecl>(D))
+    D = CatD->getClassInterface();
+  
+  return D->getAvailability();
+}