Goal:
    A : Type  B : Type  R : nat → A → B → Type  n : nat  H : True
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in All2i_nil = All2i_nil)


DEBUG:Going to execute:
idtac
Level 4: Backtrace:

Tactic failure: No generalization needed.
Level 4: Backtrace:

Tactic failure: No generalization needed.
Level 4: Backtrace:

Tactic failure: No generalization needed.