t6231.scala:4: error: Implementation restriction: local trait Bug$X$1 is unable to automatically capture the
free variable value ev$1 on behalf of <$anon: Function0>. You can manually assign it to a val inside the trait,
and refer that that val in <$anon: Function0>. For more details, see SI-6231.
      def qux = { () => ev }
                        ^
one error found