path: root/testsuite/tests/typecheck/should_fail/tcfail213.stderr

tcfail213.hs:8:1: error:
    • Potential superclass cycle for ‘C’
        one of whose superclass constraints is headed by a type family:
          ‘F a’
      Use UndecidableSuperClasses to accept this
    • In the class declaration for ‘C’