commit 1ac0f9df8dd2eef32c6a999ccf6a13bb2189a7d4
Author: Jonathan Schleifer <js@webkeks.org>
Date:   Sat Nov 23 02:55:57 2013 +0100

    SemaDeclAttr: Allow attribute format for OFStrings.

diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 6f88443..8b544af 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -191,7 +191,10 @@ static inline bool isNSStringType(QualType T, ASTContext &Ctx) {
 
   // FIXME: Should we walk the chain of classes?
   return ClsName == &Ctx.Idents.get("NSString") ||
-         ClsName == &Ctx.Idents.get("NSMutableString");
+         ClsName == &Ctx.Idents.get("NSMutableString") ||
+         ClsName == &Ctx.Idents.get("OFString") ||
+         ClsName == &Ctx.Idents.get("OFConstantString") ||
+         ClsName == &Ctx.Idents.get("OFMutableString");
 }
 
 static inline bool isCFStringType(QualType T, ASTContext &Ctx) {