T20588.hs-boot:8:1: error:
    Class ‘C’ has conflicting definitions in the module
    and its hs-boot file
    Main module: type C :: * -> Constraint
                 class C a where
                   meth :: a -> a
                   {-# MINIMAL meth #-}
    Boot file:   type C :: * -> Constraint
                 class C a where
                   meth :: a -> a
                   {-# MINIMAL meth #-}
    The methods do not match:
      The default methods associated with ‘meth’ are different

T20588.hs-boot:11:1: error:
    Class ‘D’ has conflicting definitions in the module
    and its hs-boot file
    Main module: type D :: * -> Constraint
                 class D a where
                   type T :: * -> *
                   type family T a
                     Default: Int
    Boot file:   type D :: * -> Constraint
                 class D a where
                   type T :: * -> *
                   type family T a
    The associated types do not match:
      The associated type defaults differ