{motive : Lean.IR.Expr → Sort u} →
  (t : Lean.IR.Expr) →
    ((ty : Lean.IR.IRType) → (x : Lean.IR.VarId) → motive (Lean.IR.Expr.box ty x)) →
      (Nat.hasNotBit 512 t.ctorIdx → motive t) → motive t