anchor.diff:                      then AST.ml_comp t
                       else AST.tot_comp t
                   in
  -                mk_term (Ascribed(def, t, tacopt)) def.range Expr
  +                mk_term (Ascribed(def, t, tacopt, false)) def.range Expr
               in
               let def = match args with
                    | [] -> def
  
positive.code:       | Some b ->
          let env, bv = Env.push_bv env b in
          env, S.mk_binder bv in
      let asc = snd asc in
      let asc, aq = desugar_ascription env_asc asc None in
      //if scrutinee is a name, it may appear in the ascription
      //  substitute it with the (new or annotated) binder
      let asc =
  
negative.code:       let x = Syntax.new_bv (Some t3.range) (tun_r t3.range) in
        let t_bool = mk (Tm_fvar(S.lid_as_fv C.bool_lid delta_constant None)) in
        let t1', aq1 = desugar_term_aq env t1 in
        let t1' = U.ascribe t1' (Inl t_bool, None, false) in
        let asc_opt, aq0 = desugar_match_returns env t1' asc_opt in
        let t2', aq2 = desugar_term_aq env t2 in
        let t3', aq3 = desugar_term_aq env t3 in
  