objective-C: when searching for declarations in protocol
list of classes, etc., make sure to look into protocol
definitions. // rdar://12958878


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171777 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 64b000e..d22d7a1 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -1593,6 +1593,11 @@
       NSIDecl = IDecl->lookupInheritedClass(&Context.Idents.get("NSProxy"));
   }
 
+  // If this is a forward protocol declaration, get its definition.
+  if (!PDecl->isThisDeclarationADefinition() &&
+      PDecl->getDefinition())
+    PDecl = PDecl->getDefinition();
+  
   // If a method lookup fails locally we still need to look and see if
   // the method was implemented by a base class or an inherited
   // protocol. This lookup is slow, but occurs rarely in correct code