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
  y0 : C
  l' : list C
  n : nat
  x : A
  y : B
  l : list A
  r : list B
  r0 : P n x y
  a : All2i P (Datatypes.S n) l r
  q : Q y y0
  b : All2 Q r l'
  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 := x :: l; pr2 := y0 :: l' |} |} = 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)
      → (∀ l'' : list C,
           All2 Q r l''
           → All2i R (Datatypes.S n) l l'' → All2i S (Datatypes.S n) l l'')
        → let H0 := CoreTactics.block in All2i S n (x :: l) (y0 :: l'))


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 := x :: l; pr2 := y0 :: l' |} |}
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