Goal:
  
  A : Type
  P : nat → A → Type
  n : nat
  hd : A
  tl : list A
  p : P n hd
  X : Alli P (S n) tl
  IHX : All_fold (λ (Γ : list A) (d : A), P (S n + #|Γ|) d) (List.rev tl)
  Γ : list A
  x : A
  X0 : P (S (n + #|Γ|)) x
  ============================
   (P (n + #|Γ ++ [hd]|) x)


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrrewrite@0> $1 $2

File "./theories/All_Forall.v", line 3717, characters 21-31:
Warning: Notation app_length is deprecated since 8.20.
Use length_app instead.
[deprecated-syntactic-definition-since-8.20,deprecated-since-8.20,deprecated-syntactic-definition,deprecated,default]
File "./theories/All_Forall.v", line 3717, characters 21-31:
Warning: Notation app_length is deprecated since 8.20.
Use length_app instead.
[deprecated-syntactic-definition-since-8.20,deprecated-since-8.20,deprecated-syntactic-definition,deprecated,default]