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


DEBUG:Going to execute:
<Coq.Init.Tauto.is_unit_or_eq> flags X1; Ltac.cut X2;
            [ intro; clear id
            | Ltac.cut X1; [ exact id | constructor 1; fail ] ]
Level 0: Backtrace:

f is used in hypothesis H.
Level 0: Backtrace:

f is used in hypothesis H.
Level 0: Backtrace:

f is used in hypothesis H.
Level 0: Backtrace:

f is used in hypothesis H.
Level 0: Backtrace:

f is used in hypothesis H.
Level 1: Backtrace:

f is used in hypothesis H.
Level 0: Backtrace:

f is used in hypothesis H.
Level 2: Backtrace:

Not convertible.
Level 2: Backtrace:

Not convertible.
Level 2: Backtrace:

Not convertible.
Level 1: Backtrace:

Not convertible.