Goal:
  
  A : Type
  B : Type
  C : Type
  P : nat → A → B → Type
  Q : B → C → Type
  R : nat → A → C → Type
  S : nat → A → C → Type
  n : nat
  c1 : sigma (λ _ : nat, sigma (λ _ : list A, list C))
  c : All2i R (pr1 c1) (pr1 (pr2 c1)) (pr2 (pr2 c1))
  ============================
   ({| pr1 := n; pr2 := {| pr1 := []; pr2 := [] |} |} = c1
    → let H := CoreTactics.block in
      (∀ (n : nat) (x : A) (y : B) (z : C),
         P n x y → Q y z → R n x z → S n x z)
      → let H0 := CoreTactics.block in All2i S n [] [])


DEBUG:Going to execute:
try rename id into id',id' into id
Level 3: evaluation returns
try rename id into id',id' into id; cont id'1 id
where
t := {| pr1 := n; pr2 := {| pr1 := []; pr2 := [] |} |}
of type
constr
id'1 := c1
of type
constr
id' := c
of type
constr
id := c
of type
constr
cont := fun id id' => DepElim.decompose_exists id id'
        where
        id := c
        of type
        constr
of type
tacvalue of type tacvalue