{motive_2 : Lean.Meta.Grind.AC.EqCnstrProof → Sort u} →
  (ctorIdx : ℕ) →
    (t : Lean.Meta.Grind.AC.EqCnstrProof) →
      ctorIdx = t.ctorIdx → Lean.Meta.Grind.AC.EqCnstrProof.ctorElimType ctorIdx → motive_2 t