Goal:
  
  A : Type
  P : nat → A → Type
  f : A → A
  n : nat
  H : ∀ (n : nat) (x : A), P n x → f x = x
  ============================
   ([] = [])


DEBUG:Going to execute:
<Coq.Init.Tauto.is_disj> flags X1; elim id; intro; clear id
Level 2: evaluation returns
<coq-core.plugins.tauto::is_disj@0>
where
tauto_flags := 
of type
tauto_flags
X1 := nat
of type
constr of type tacvalue

Level 2: Backtrace:

Tactic failure.
Level 2: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.