Goal:
    A : Type  P : list A → A → Type
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in All_fold_nil P = All_fold_nil P)


DEBUG:Going to execute:
DepElim.simplify_IH_hyps
Level 6: Backtrace:

Tactic failure (level 1).
Level 5: Backtrace:

Tactic failure.
Level 4: Backtrace:

Tactic failure.