2 files changed, 6 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 38b720ffc8..38a364ff88 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -30,6 +30,7 @@ module ActiveRecord
       @offsets = {}
       @loaded = false
       @predicate_builder = predicate_builder
+      @delegate_to_klass = false
     end
 
     def initialize_copy(other)
@@ -453,6 +454,7 @@ module ActiveRecord
     end
 
     def reset
+      @delegate_to_klass = false
       @to_sql = @arel = @loaded = @should_eager_load = nil
       @records = [].freeze
       @offsets = {}
diff --git a/activerecord/lib/active_record/relation/delegation.rb b/activerecord/lib/active_record/relation/delegation.rb
index 27450ab8b3..488f71cdde 100644
--- a/activerecord/lib/active_record/relation/delegation.rb
+++ b/activerecord/lib/active_record/relation/delegation.rb
@@ -82,8 +82,10 @@ module ActiveRecord
           if @klass.respond_to?(method)
             self.class.delegate_to_scoped_klass(method)
             scoping { @klass.public_send(method, *args, &block) }
-          elsif defined?(@delegate_to_klass) &&
-            @delegate_to_klass && @klass.respond_to?(method, true)
+          elsif @delegate_to_klass && @klass.respond_to?(method, true)
+            ActiveSupport::Deprecation.warn \
+              "Delegating missing #{method} method to #{@klass}. " \
+              "Accessibility of private/protected class methods in :scope is deprecated and will be removed in Rails 6.0."
             @klass.send(method, *args, &block)
           elsif arel.respond_to?(method)
             ActiveSupport::Deprecation.warn \