objective-c: fixes a regression in looking up names

in class extensions and categories by recent refactoring
of objc class ASTs. // rdar://1066654

llvm-svn: 147982

clang/lib/Sema/SemaDecl.cpp

@@ -1255,8 +1255,11 @@ ObjCInterfaceDecl *Sema::getObjCInterfaceDecl(IdentifierInfo *&Id,
       Id = IDecl->getIdentifier();
     }
   }
-
-  return dyn_cast_or_null<ObjCInterfaceDecl>(IDecl);
+  ObjCInterfaceDecl *Def = dyn_cast_or_null<ObjCInterfaceDecl>(IDecl);
+  // This routine must always return a class definition, if any.
+  if (Def && Def->getDefinition())
+      Def = Def->getDefinition();
+  return Def;
 }
 
 /// getNonFieldDeclScope - Retrieves the innermost scope, starting

clang/test/SemaObjC/ContClassPropertyLookup.m

@@ -16,3 +16,23 @@
 @implementation MyObject
 @synthesize foo = _foo;
 @end
+
+// rdar://10666594
+@interface MPMediaItem
+@end
+
+@class MPMediaItem;
+
+@interface MPMediaItem ()
+@property (nonatomic, readonly) id title;
+@end
+
+@interface PodcastEpisodesViewController
+@end
+
+@implementation PodcastEpisodesViewController
+- (id) Meth {
+    MPMediaItem *episode;
+    return episode.title;
+}
+@end