T3092.hs:5:1: [GHC-06204]
    Illegal family instance for ‘T’
      (T is not an indexed type family)
    In the data instance declaration for ‘T’

T3092.hs:8:1: [GHC-06204]
    Illegal family instance for ‘S’
      (S is not an indexed type family)
    In the type instance declaration for ‘S’