algTcFields :: [(FieldLabel, Type, Id)],
-- Its fields (empty if none):
-- * field name
- -- * its type (scoped over tby tyConTyVars)
+ -- * its type (scoped over by tyConTyVars)
-- * record selector (name = field name)
algTcStupidTheta :: [PredType], -- The "stupid theta" for the data type