Keep track of all declarations of an Objective-C class (both forward
declarations and definitions) as ObjCInterfaceDecls within the same
redeclaration chain. This new representation matches what we do for
C/C++ variables/functions/classes/templates/etc., and makes it
possible to answer the query "where are all of the declarations of
this class?"

llvm-svn: 146679
diff --git a/clang/lib/ARCMigrate/Transforms.cpp b/clang/lib/ARCMigrate/Transforms.cpp
index e208e84..21df2578 100644
--- a/clang/lib/ARCMigrate/Transforms.cpp
+++ b/clang/lib/ARCMigrate/Transforms.cpp
@@ -80,7 +80,7 @@
     ObjCInterfaceDecl *Class = ObjT->getInterfaceDecl();
     if (!AllowOnUnknownClass && (!Class || Class->getName() == "NSObject"))
       return false; // id/NSObject is not safe for weak.
-    if (!AllowOnUnknownClass && Class->isForwardDecl())
+    if (!AllowOnUnknownClass && !Class->hasDefinition())
       return false; // forward classes are not verifiable, therefore not safe.
     if (Class->isArcWeakrefUnavailable())
       return false;