class ActiveRecord::Associations::AssociationScope

def add_constraints(scope, owner, chain)

def add_constraints(scope, owner, chain)
  scope = last_chain_scope(scope, chain.last, owner)
  chain.each_cons(2) do |reflection, next_reflection|
    scope = next_chain_scope(scope, reflection, next_reflection)
  end
  chain_head = chain.first
  chain.reverse_each do |reflection|
    reflection.constraints.each do |scope_chain_item|
      item = eval_scope(reflection, scope_chain_item, owner)
      if scope_chain_item == chain_head.scope
        scope.merge! item.except(:where, :includes, :unscope, :order)
      elsif !item.references_values.empty?
        scope.merge! item.only(:joins, :left_outer_joins)
        associations = item.eager_load_values | item.includes_values
        unless associations.empty?
          scope.joins! item.construct_join_dependency(associations, Arel::Nodes::OuterJoin)
        end
      end
      reflection.all_includes do
        scope.includes_values |= item.includes_values
      end
      scope.unscope!(*item.unscope_values)
      scope.where_clause += item.where_clause
      scope.order_values = item.order_values | scope.order_values
    end
  end
  scope
end