T13267.hs:6:10: error: [GHC-53946]
    • Illegal instance for a type synonym
      A class instance must be for a class
    • In the instance declaration for ‘C1 Int’

T13267.hs:10:10: error: [GHC-53946]
    • Illegal instance for a type synonym
      A class instance must be for a class
    • In the instance declaration for ‘C2 Int’