Goal:
  
  A : Type
  B : Type
  R : nat → A → B → Type
  n : nat
  x : A
  y : B
  l : list A
  r : list B
  r0 : R n x y
  a : All2i R (S n) l r
  b0 : All2i R n (x :: l) (y :: r)
  b'' : nat
  x0 : A
  y0 : B
  l0 : list A
  r1 : list B
  r2 : R b'' x0 y0
  b : All2i R (S b'') l0 r1
  ============================
   ({|
      pr1 := {| pr1 := n; pr2 := {| pr1 := x :: l; pr2 := y :: r |} |};
      pr2 := b0
    |} =
    {|
      pr1 := {| pr1 := b''; pr2 := {| pr1 := x0 :: l0; pr2 := y0 :: r1 |} |};
      pr2 := All2i_cons r2 b
    |}
    → let H := CoreTactics.block in
      NoConfusionHom_All2i A B R n (x :: l) (y :: r) (All2i_cons r0 a) b0
      → let H0 := CoreTactics.block in All2i_cons r0 a = b0)


DEBUG:Going to execute:
match goal with
           | |- context [ eq_rect_r _ _ eq_refl ] => progress simpl eq_rect_r
           | |- context [ eq_rect _ _ _ _ eq_refl ] => progress simpl eq_rect
           | |- context [ Prop.Logic.transport _ eq_refl _ ] =>
                 progress simpl Prop.Logic.transport
           | |- context [ Logic.eq_elim _ _ _ _ _ eq_refl ] =>
                 progress simpl eq_rect
           | |- context [ Logic.eq_elim_r _ _ _ _ eq_refl ] =>
                 progress simpl Logic.eq_elim_r
           | |- context [ noConfusion_inv _ ] =>
                 progress simpl noConfusion_inv
           | |- DepElim.opaque_ind_pack_eq_inv ?G eq_refl =>
                 apply (DepElim.simplify_ind_pack_inv B x p G)
           | |- let _ := CoreTactics.block in _ => fail 1
           | |- _ => simplify * || simplify ?; cbv beta
           | |- _ → ?B =>
                 let ty := type of B in
                 intro || (let H := fresh in
                           intro
                           H)
           | |- ∀ x, _ => let H := fresh x in
                          intro
                          H
           | |- _ => intro
           end