anchor.diff:                      | [] -> [(("", Term_sort), "Unknown assertion failed", Range.dummyRange)]
                       | _ -> errs in
               begin match !fuel_trace with
  -            | ReplayFuelTrace _ ->
  -                raise <| Util.Failure "Query should not fail when replaying fuel trace."
  +            | ReplayFuelTrace (fname, _) ->
  +                raise <| Util.Failure (Util.format1 "Query failed while replaying cached fuel trace; please delete the related file (%s) and try again" fname)
               | _ ->
                   fuel_trace := FuelTraceUnavailable
               end;
  
positive.code: type fuel_trace_status =
      | FuelTraceUnavailable
      | RecordFuelTrace of list<(int * int)>
      | ReplayFuelTrace of list<(int * int)>
  
  let fuel_trace : ref<fuel_trace_status> = Util.mk_ref <| FuelTraceUnavailable
  
  
negative.code:         @[Term.CheckSat]
          @suffix in
  
      let check (p:decl) =        
          let cached_config =
              match !fuel_trace with 
              | ReplayFuelTrace (fname, hd::tl) ->
                  let fuel, ifuel = hd in
                  fuel_trace := ReplayFuelTrace (fname, tl);
                  Some (fname, fuel, ifuel)
              | _ ->
                  None
          in
          let initial_config = 
              match cached_config with 
              | Some (_, fuel, ifuel) -> (fuel, ifuel)
              | None -> (!Options.initial_fuel, !Options.initial_ifuel) 
          in
          let alt_configs = 
  