{motive_2 : Lean.IR.FnBody → Sort u} →
  (t : Lean.IR.FnBody) →
    t.ctorIdx = 6 →
      ((x : Lean.IR.VarId) →
          (n : ℕ) → (c persistent : Bool) → (b : Lean.IR.FnBody) → motive_2 (Lean.IR.FnBody.inc x n c persistent b)) →
        motive_2 t