Fix private methods which are delegated to. This previously worked because Module#delegate previously ignored method visibility.

activerecord/lib/active_record/associations/association.rb

@@ -151,20 +151,20 @@ module ActiveRecord
         reset
       end
 
+      def interpolate(sql, record = nil)
+        if sql.respond_to?(:to_proc)
+          owner.send(:instance_exec, record, &sql)
+        else
+          sql
+        end
+      end
+
       private
 
         def find_target?
           !loaded? && (!owner.new_record? || foreign_key_present?) && klass
         end
 
-        def interpolate(sql, record = nil)
-          if sql.respond_to?(:to_proc)
-            owner.send(:instance_exec, record, &sql)
-          else
-            sql
-          end
-        end
-
         def creation_attributes
           attributes = {}
 

activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb

@@ -2,6 +2,11 @@ module ActiveRecord
   # = Active Record Belongs To Polymorphic Association
   module Associations
     class BelongsToPolymorphicAssociation < BelongsToAssociation #:nodoc:
+      def klass
+        type = owner[reflection.foreign_type]
+        type.presence && type.constantize
+      end
+
       private
 
         def replace_keys(record)
@@ -17,11 +22,6 @@ module ActiveRecord
           reflection.polymorphic_inverse_of(record.class)
         end
 
-        def klass
-          type = owner[reflection.foreign_type]
-          type.presence && type.constantize
-        end
-
         def raise_on_type_mismatch(record)
           # A polymorphic association cannot have a type mismatch, by definition
         end