Generically derived Serial instance for mutually recursive data type causes infinite loop about smallcheck

[Bodigrim]

Honestly, the linked commit with 945 additions and 631 deletions is not something I can easily investigate.

In general smallcheck seems to be capable to generate Serial for Generic data types that are recursive:

> :set -XDeriveGeneric -XDeriveAnyClass
> import GHC.Generics (Generic)
> data List a = Nil | Cons a (List a) deriving (Show, Generic)
> instance (Monad m, Serial m a) => Serial m (List a)
> listSeries 5 :: [List ()]
[Nil,Cons () Nil,Cons () (Cons () Nil),Cons () (Cons () (Cons () Nil)),Cons () (Cons () (Cons () (Cons () Nil)))]

Do you possibly have a smaller example?

[Bodigrim]

Feel free to reopen if you come with a smaller reproducer.