Refine r251469 to give better (and more localizable) diagnostics

for all the reasons that ARC makes things implicitly unavailable.

llvm-svn: 251496

clang/lib/Sema/SemaDeclObjC.cpp

@@ -100,9 +100,8 @@ bool Sema::checkInitMethod(ObjCMethodDecl *method,
   // If we're in a system header, and this is not a call, just make
   // the method unusable.
   if (receiverTypeIfCall.isNull() && getSourceManager().isInSystemHeader(loc)) {
-    method->addAttr(UnavailableAttr::CreateImplicit(Context,
-                "init method returns a type unrelated to its receiver type",
-                loc));
+    method->addAttr(UnavailableAttr::CreateImplicit(Context, "",
+                      UnavailableAttr::IR_ARCInitReturnsUnrelated, loc));
     return true;
   }