instance method build_joins

# File activerecord/lib/active_record/relation/query_methods.rb, line 1865
      def build_joins(join_sources, aliases = nil)
        return join_sources if joins_values.empty? && left_outer_joins_values.empty?

        buckets, join_type = build_join_buckets

        named_joins   = buckets[:named_join]
        stashed_joins = buckets[:stashed_join]
        leading_joins = buckets[:leading_join]
        join_nodes    = buckets[:join_node]

        join_sources.concat(leading_joins) unless leading_joins.empty?

        unless named_joins.empty? && stashed_joins.empty?
          alias_tracker = alias_tracker(leading_joins + join_nodes, aliases)
          join_dependency = construct_join_dependency(named_joins, join_type)
          join_sources.concat(join_dependency.join_constraints(stashed_joins, alias_tracker, references_values))
        end

        join_sources.concat(join_nodes) unless join_nodes.empty?
        join_sources
      end