Goal:
    A : Type  P : list A → list A → A → A → Type  Q : list A → A → Type
  ============================
   (All_fold Q [] × All_fold Q [])


DEBUG:Going to execute:
Ltac.split
Level 2: evaluation returns
<coq-core.plugins.tauto::is_conj@0>
where
tauto_flags := 
of type
tauto_flags
X1 := All_fold Q [] × All_fold Q []
of type
constr of type tacvalue