Goal:
  
  A : Type
  P : A → Type
  p : A → bool
  x : A
  l : list A
  p0 : P x
  X : All P l
  IHX : ∀ p : A → bool, (∀ x : A, P x → p x) → forallb p l
  H : ∀ x : A, P x → p x
  ============================
   (p x ∧ forallb p l)


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 := p x ∧ forallb p l
of type
constr of type tacvalue