Merge branch 'counter-examples'

doc/manpages.tex

@@ -450,6 +450,20 @@ are grouped together under several tabs.
   decision by clicking on it.
 \end{description}
 
+% \subsection{Displaying Counterexamples}
+%
+% how to use counterexamples - explain labels, projections, the option --get-ce of why3prove and the setting in why3ide
+%
+% problem with set logic and counterexamples
+%
+% which provers
+%
+% where it is displayed
+%
+% how to interpret the display
+%
+% example
+
 \subsection{Additional Command-Line Options}
 
 The \texttt{ide} command also accepts the following options described for the command \texttt{prove} in Section~\ref{sec:proveoptions}.

drivers/cvc4_15.drv

@@ -12,9 +12,6 @@ prelude "(set-logic AUFBVDTLIRA)"
    does not seem to include DT
 *)
 
-(* Counterexamples: makes it possible to get rid of more quantifiers while introducing premises *)
-(* transformation "split_intro" *)
-
 (* Counterexamples: set model parser *)
 model_parser "smtv2"
 
@@ -24,9 +21,7 @@ import "discrimination.gen"
 
 transformation "inline_trivial"
 transformation "eliminate_builtin"
-(* temporarily disabled: too much experimental
 transformation "detect_polymorphism"
-*)
 transformation "eliminate_definition_if_poly"
 transformation "eliminate_inductive"
 transformation "eliminate_algebraic_if_poly"

examples/tests/cvc4-models.mlw

@@ -22,7 +22,11 @@ module M
   ensures { !x < old !x }
   =
   incr x;
-  while "model" "model_trace:cond" !x > 0 do invariant { !x >= 0 } variant { !x } x := !x - 1 done
+  while "model" "model_trace:cond" !x > 0 do
+  invariant { !x >= 0 }
+  variant { !x }
+    x := !x - 1
+  done
 
   (**************************************
    ** Getting counterexamples for maps **

examples/use_api/create_session.ml

@@ -93,6 +93,7 @@ let add_proofs_attempts g =
           ~obsolete:true
           ~archived:false
           ~timelimit:5
+	  ~steplimit:(-1)
           ~memlimit:1000
           ~edit:None
           g p.Whyconf.prover Session.Scheduled
@@ -106,5 +107,3 @@ let () =
 
 (* save the session on disk *)
 let () = Session.save_session config env_session.Session.session
-
-

src/coq-tactic/why3tac.ml4

@@ -1285,7 +1285,7 @@ let why3tac ?(timelimit=timelimit) s gl =
     match res.pr_answer with
       | Valid -> admit_as_an_axiom gl
       | Invalid -> error "Invalid"
-      | Unknown s -> error ("Don't know: " ^ s)
+      | Call_provers.Unknown (s, _) -> error ("Don't know: " ^ s)
       | Call_provers.Failure s -> error ("Failure: " ^ s)
       | Call_provers.Timeout -> error "Timeout"
       | OutOfMemory -> error "Out Of Memory"

src/driver/call_provers.ml

@@ -16,6 +16,29 @@ let debug = Debug.register_info_flag "call_prover"
   ~desc:"Print@ debugging@ messages@ about@ prover@ calls@ \
          and@ keep@ temporary@ files."
 
+type reason_unknown =
+  | Resourceout
+  | Other
+
+type prover_answer =
+  | Valid
+  | Invalid
+  | Timeout
+  | OutOfMemory
+  | StepLimitExceeded
+  | Unknown of (string * reason_unknown option)
+  | Failure of string
+  | HighFailure
+
+type prover_result = {
+  pr_answer : prover_answer;
+  pr_status : Unix.process_status;
+  pr_output : string;
+  pr_time   : float;
+  pr_steps  : int;		(* -1 if unknown *)
+  pr_model  : model;
+}
+
 (** time regexp "%h:%m:%s" *)
 type timeunit =
   | Hour
@@ -83,26 +106,15 @@ let rec grep_steps out = function
       with _ -> grep_steps out l
     end
 
-(** *)
-
-type prover_answer =
-  | Valid
-  | Invalid
-  | Timeout
-  | OutOfMemory
-  | StepLimitExceeded
-  | Unknown of string
-  | Failure of string
-  | HighFailure
-
-type prover_result = {
-  pr_answer : prover_answer;
-  pr_status : Unix.process_status;
-  pr_output : string;
-  pr_time   : float;
-  pr_steps  : int;		(* -1 if unknown *)
-  pr_model  : model;
-}
+let grep_reason_unknown out =
+  try
+    let re = Str.regexp "^(:reason-unknown \\([^)]*\\)" in
+    ignore (Str.search_forward re out 0);
+    match  (Str.matched_group 1 out) with
+    | "resourceout" -> Resourceout
+    | _ -> Other
+  with Not_found ->
+    Other
 
 type prover_result_parser = {
   prp_regexps     : (Str.regexp * prover_answer) list;
@@ -112,15 +124,20 @@ type prover_result_parser = {
   prp_model_parser : Model_parser.model_parser;
 }
 
+let print_unknown_reason fmt r =
+  match r with
+  | Some Resourceout -> fprintf fmt " because of resource limit reached "
+  | _ -> ()
+
 let print_prover_answer fmt = function
   | Valid -> fprintf fmt "Valid"
   | Invalid -> fprintf fmt "Invalid"
   | Timeout -> fprintf fmt "Timeout"
   | OutOfMemory -> fprintf fmt "Ouf Of Memory"
   | StepLimitExceeded -> fprintf fmt "Step limit exceeded"
-  | Unknown "" -> fprintf fmt "Unknown"
+  | Unknown ("", r) -> fprintf fmt "Unknown%a" print_unknown_reason r
   | Failure "" -> fprintf fmt "Failure"
-  | Unknown s -> fprintf fmt "Unknown (%s)" s
+  | Unknown (s, r) -> fprintf fmt "Unknown %a(%s)" print_unknown_reason r s
   | Failure s -> fprintf fmt "Failure (%s)" s
   | HighFailure -> fprintf fmt "HighFailure"
 
@@ -151,7 +168,7 @@ let rec grep out l = match l with
         ignore (Str.search_forward re out 0);
         match pa with
         | Valid | Invalid | Timeout | OutOfMemory | StepLimitExceeded -> pa
-        | Unknown s -> Unknown (Str.replace_matched s out)
+        | Unknown (s, ru) -> Unknown ((Str.replace_matched s out), ru)
         | Failure s -> Failure (Str.replace_matched s out)
         | HighFailure -> assert false
       with Not_found -> grep out l end
@@ -188,6 +205,10 @@ let parse_prover_run res_parser time out ret on_timelimit timelimit ~printer_map
   Debug.dprintf debug "Call_provers: prover output:@\n%s@." out;
   let time = Opt.get_def (time) (grep_time out res_parser.prp_timeregexps) in
   let steps = Opt.get_def (-1) (grep_steps out res_parser.prp_stepregexps) in
+  let reason_unknown = grep_reason_unknown out in
+  let ans = match ans with
+    | Unknown (s, _) -> Unknown (s, Some reason_unknown)
+    | _ -> ans in
   let ans = match ans with
     | Unknown _ | HighFailure when on_timelimit && timelimit > 0
       && time >= (0.9 *. float timelimit) -> Timeout

src/driver/call_provers.mli

@@ -15,6 +15,13 @@ open Model_parser
 
 (** {2 data types for prover answers} *)
 
+(** The reason why unknown was reported *)
+type reason_unknown =
+  | Resourceout
+  (** Out of resources  *)
+  | Other
+  (** Other reason *)
+
 type prover_answer =
   | Valid
       (** The task is valid according to the prover *)
@@ -26,7 +33,7 @@ type prover_answer =
       (** the task runs out of memory *)
   | StepLimitExceeded
       (** the task required more steps than the limit provided *)
-  | Unknown of string
+  | Unknown of (string * reason_unknown option)
       (** The prover can't determine if the task is valid *)
   | Failure of string
       (** The prover reports a failure *)
@@ -45,8 +52,8 @@ type prover_result = {
   (** The time taken by the prover *)
   pr_steps  : int;
   (** The number of steps taken by the prover (-1 if not available) *)
-  (** The model produced by a the solver *)
   pr_model  : model;
+  (** The model produced by a the solver *)
 }
 
 val print_prover_answer : Format.formatter -> prover_answer -> unit

src/driver/driver.ml

@@ -92,7 +92,7 @@ let load_driver = let driver_tag = ref (-1) in fun env file extra_files ->
     | RegexpOutOfMemory s -> add_to_list regexps (Str.regexp s, OutOfMemory)
     | RegexpStepLimitExceeded s ->
       add_to_list regexps (Str.regexp s, StepLimitExceeded)
-    | RegexpUnknown (s,t) -> add_to_list regexps (Str.regexp s, Unknown t)
+    | RegexpUnknown (s,t) -> add_to_list regexps (Str.regexp s, Unknown (t, None))
     | RegexpFailure (s,t) -> add_to_list regexps (Str.regexp s, Failure t)
     | TimeRegexp r -> add_to_list timeregexps (Call_provers.timeregexp r)
     | StepRegexp (r,ns) ->
@@ -103,7 +103,7 @@ let load_driver = let driver_tag = ref (-1) in fun env file extra_files ->
     | ExitCodeOutOfMemory s -> add_to_list exitcodes (s, OutOfMemory)
     | ExitCodeStepLimitExceeded s ->
       add_to_list exitcodes (s, StepLimitExceeded)
-    | ExitCodeUnknown (s,t) -> add_to_list exitcodes (s, Unknown t)
+    | ExitCodeUnknown (s,t) -> add_to_list exitcodes (s, Unknown (t, None))
     | ExitCodeFailure (s,t) -> add_to_list exitcodes (s, Failure t)
     | Filename s -> set_or_raise loc filename s "filename"
     | Printer s -> set_or_raise loc printer s "printer"

src/driver/parse_smtv2_model_lexer.mll

@@ -13,6 +13,7 @@ rule token = parse
     { token lexbuf }
   | space+ as space_str
       { SPACE (space_str) }
+  | "mk_t__ref"(num*) { MK_T_REF }
   | "store" { STORE }
   | "const" { CONST }
   | "as" { AS }

src/driver/parse_smtv2_model_parser.mly

@@ -13,6 +13,7 @@
 %token <string * string> DEC_STR
 %token <string * string> MINUS_DEC_STR
 %token LPAREN RPAREN
+%token MK_T_REF
 %token EOF
 %%
 
@@ -53,6 +54,7 @@ text_without_int:
 | AS { "as" }
 
 value:
+| LPAREN MK_T_REF SPACE value RPAREN { $4 }
 | integer { $1 }
 | decimal { $1 }
 | other_val_str { Model_parser.Unparsed $1 }

src/ide/gmain.ml

@@ -1016,7 +1016,7 @@ let prover_on_selected_goals pr =
        M.run_prover
          (env_session()) sched
          ~context_unproved_goals_only:!context_unproved_goals_only
-         ~cntexample ~timelimit ~memlimit
+         ~cntexample ~timelimit ~steplimit:(-1) ~memlimit
          pr a
       with e ->
         eprintf "@[Exception raised while running a prover:@ %a@.@]"
@@ -1541,11 +1541,11 @@ let test_strategy () =
     Whyconf.filter_one_prover config fp
   in
   [|
-    Strategy.Icall_prover(altergo.Whyconf.prover,1,1000);
-    Strategy.Icall_prover(cvc4.Whyconf.prover,1,1000);
+    Strategy.Icall_prover(altergo.Whyconf.prover,1,-1,1000);
+    Strategy.Icall_prover(cvc4.Whyconf.prover,1,0,1000);
     Strategy.Itransform(split_transformation,0); (* goto 0 on success *)
-    Strategy.Icall_prover(altergo.Whyconf.prover,10,4000);
-    Strategy.Icall_prover(cvc4.Whyconf.prover,10,4000);
+    Strategy.Icall_prover(altergo.Whyconf.prover,10,-1,4000);
+    Strategy.Icall_prover(cvc4.Whyconf.prover,10,-1,4000);
   |]
 
 (*

src/printer/smtv2.ml

@@ -176,11 +176,33 @@ let model_label = Ident.create_label "model"
 let model_vc_term_label = Ident.create_label "model_vc"
   (* This label identifies the term that triggers the VC. *)
 
+let add_model_element el info_model =
+(** Add element el (term) to info_model.
+    If an element with the same hash (the same set of labels + the same
+    location) as the element el already exists in info_model, replace it with el.
+
+    The reason is that  we do not want to display two model elements with the same
+    name in the same location and usually it is better to display the last one.
+
+    Note that two model elements can have the same name and location if why is used
+    as an intemediate language and the locations are locations in the source language.
+    Then, more why constructs (terms) can represent a single construct in the source
+    language and more terms have thus the same model name and location. This happens,
+    e.g., if why code is generated from SPARK. There, the first iteration of while
+    cycle is unrolled in some cases. If the task contains both a term representing a
+    variable in the first iteration of unrolled loop and a term representing the variable
+    in the subsequent loop iterations, only the latter is relevant for the counterexample
+    and it is the one that comes after the former one (and that is why we always keep the
+    last term).
+*)
+  let info_model = S.remove el info_model in
+  S.add el info_model
+
 let collect_model_ls info ls =
   if ls.ls_args = [] && Slab.mem model_label ls.ls_name.id_label then
     let t = t_app ls [] ls.ls_value in
     info.info_model <-
-      S.add
+      add_model_element
       (t_label ?loc:ls.ls_name.id_loc ls.ls_name.id_label t) info.info_model
 
 let model_trace_regexp = Str.regexp "model_trace:"
@@ -267,7 +289,7 @@ let rec print_term info fmt t =
   debug_print_term "Printing term: " t;
 
   if Slab.mem model_label t.t_label then
-    info.info_model <- S.add t info.info_model;
+    info.info_model <- add_model_element t info.info_model;
 
   check_enter_vc_term t info;
 
@@ -318,7 +340,7 @@ let rec print_term info fmt t =
 		    model_trace_for_postcondition ~labels:ls.ls_name.id_label info in
 		let _t_check_pos = t_label ~loc labels t in
 		(* TODO: temporarily disable collecting variables inside the term triggering VC *)
-		(*info.info_model <- S.add t_check_pos info.info_model;*)
+		(*info.info_model <- add_model_element t_check_pos info.info_model;*)
 		()
 	    end;
 	    fprintf fmt "@[%a@]" print_ident ls.ls_name
@@ -361,7 +383,7 @@ let rec print_term info fmt t =
 and print_fmla info fmt f =
   debug_print_term "Printing formula: " f;
   if Slab.mem model_label f.t_label then
-    info.info_model <- S.add f info.info_model;
+    info.info_model <- add_model_element f info.info_model;
 
   check_enter_vc_term f info;
 
@@ -560,6 +582,8 @@ let print_prop_decl vc_loc cntexample args info fmt k pr f = match k with
       let model_list = S.elements info.info_model in
       fprintf fmt "@[(check-sat)@]@\n";
       print_info_model cntexample fmt model_list info;
+      (* (get-info :reason-unknown) *)
+      fprintf fmt "@[(get-info :reason-unknown)@]@\n";
 
       args.printer_mapping <- { lsymbol_m = args.printer_mapping.lsymbol_m;
 				vc_term_loc = vc_loc;

src/session/session.ml

@@ -158,6 +158,7 @@ and 'a proof_attempt =
     proof_parent : 'a goal;
     mutable proof_state : proof_attempt_status;
     mutable proof_timelimit : int;
+    mutable proof_steplimit : int;
     mutable proof_memlimit : int;
     mutable proof_obsolete : bool;
     mutable proof_archived : bool;
@@ -490,10 +491,10 @@ let get_used_provers_with_stats session =
     (fun pa ->
       (* record mostly used pa.proof_timelimit pa.proof_memlimit *)
       let prover = pa.proof_prover in
-      let timelimits,memlimits =
+      let timelimits,steplimits,memlimits =
         try PHprover.find prover_table prover
         with Not_found ->
-          let x = (Hashtbl.create 5,Hashtbl.create 5) in
+          let x = (Hashtbl.create 5,Hashtbl.create 5,Hashtbl.create 5) in
           PHprover.add prover_table prover x;
           x
       in
@@ -501,11 +502,16 @@ let get_used_provers_with_stats session =
         try Hashtbl.find timelimits pa.proof_timelimit
         with Not_found -> 0
       in
+      let sf =
+	try Hashtbl.find steplimits pa.proof_steplimit
+	with Not_found -> 0
+      in
       let mf =
         try Hashtbl.find memlimits pa.proof_timelimit
         with Not_found -> 0
       in
       Hashtbl.replace timelimits pa.proof_timelimit (tf+1);
+      Hashtbl.replace steplimits pa.proof_steplimit (sf+1);
       Hashtbl.replace memlimits pa.proof_memlimit (mf+1))
     session;
   prover_table
@@ -578,11 +584,12 @@ let save_int_def name def fmt n =
 
 let opt_string = opt save_string
 
-let save_proof_attempt fmt ((id,tl,ml),a) =
+let save_proof_attempt fmt ((id,tl,sl,ml),a) =
   fprintf fmt
-    "@\n@[<h><proof@ prover=\"%i\"%a%a%a%a%a>"
+    "@\n@[<h><proof@ prover=\"%i\"%a%a%a%a%a%a>"
     id
     (save_int_def "timelimit" tl) a.proof_timelimit
+    (save_int_def "steplimit" sl) a.proof_steplimit
     (save_int_def "memlimit" ml) a.proof_memlimit
     (opt_string "edited") a.proof_edited_as
     (save_bool_def "obsolete" false) a.proof_obsolete
@@ -603,7 +610,7 @@ module Compr = Compress.Compress_z
 
 type save_ctxt = {
   prover_ids : int PHprover.t;
-  provers : (int * int * int) Mprover.t;
+  provers : (int * int * int * int) Mprover.t;
   ch_shapes : Compr.out_channel;
 }
 
@@ -633,7 +640,7 @@ let rec save_goal ctxt fmt g =
   let l = PHprover.fold
     (fun _ a acc -> (Mprover.find a.proof_prover ctxt.provers, a) :: acc)
     g.goal_external_proofs [] in
-  let l = List.sort (fun ((i1,_,_),_) ((i2,_,_),_) -> compare i1 i2) l in
+  let l = List.sort (fun ((i1,_,_,_),_) ((i2,_,_,_),_) -> compare i1 i2) l in
   List.iter (save_proof_attempt fmt) l;
   let l = PHstr.fold (fun _ t acc -> t :: acc) g.goal_transformations [] in
   let l = List.sort (fun t1 t2 -> compare t1.transf_name t2.transf_name) l in
@@ -746,13 +753,19 @@ let save_file ctxt fmt _ f =
   List.iter (save_theory ctxt fmt) f.file_theories;
   fprintf fmt "@]@\n</file>"
 
-let get_prover_to_save prover_ids p (timelimits,memlimits) provers =
+let get_prover_to_save prover_ids p (timelimits,steplimits,memlimits) provers =
   let mostfrequent_timelimit,_ =
     Hashtbl.fold
       (fun t f ((_,f') as t') -> if f > f' then (t,f) else t')
       timelimits
       (0,0)
   in
+  let mostfrequent_steplimit,_ =
+    Hashtbl.fold
+      (fun s f ((_,f') as s') -> if f > f' then (s,f) else s')
+      steplimits
+      (0,0)
+  in
   let mostfrequent_memlimit,_ =
     Hashtbl.fold
       (fun m f ((_,f') as m') -> if f > f' then (m,f) else m')
@@ -778,17 +791,17 @@ let get_prover_to_save prover_ids p (timelimits,memlimits) provers =
         PHprover.add prover_ids p !id;
         !id
   in
-  Mprover.add p (id,mostfrequent_timelimit,mostfrequent_memlimit) provers
+  Mprover.add p (id,mostfrequent_timelimit,mostfrequent_steplimit,mostfrequent_memlimit) provers
 
 
-let save_prover fmt id (p,mostfrequent_timelimit,mostfrequent_memlimit) =
+let save_prover fmt id (p,mostfrequent_timelimit,mostfrequent_steplimit,mostfrequent_memlimit) =
   fprintf fmt "@\n@[<h><prover@ id=\"%i\"@ name=\"%a\"@ \
-               version=\"%a\"%a@ timelimit=\"%d\"@ memlimit=\"%d\"/>@]"
+               version=\"%a\"%a@ timelimit=\"%d\"@ steplimit=\"%d\"@ memlimit=\"%d\"/>@]"
     id save_string p.C.prover_name save_string p.C.prover_version
     (fun fmt s -> if s <> "" then fprintf fmt "@ alternative=\"%a\""
         save_string s)
     p.C.prover_altern
-    mostfrequent_timelimit mostfrequent_memlimit
+    mostfrequent_timelimit mostfrequent_steplimit mostfrequent_memlimit
 
 let save fname shfname _config session =
   let ch = open_out fname in
@@ -811,8 +824,8 @@ let save fname shfname _config session =
   in
   let provers_to_save =
     Mprover.fold
-      (fun p (id,mostfrequent_timelimit,mostfrequent_memlimit) acc ->
-        Mint.add id (p,mostfrequent_timelimit,mostfrequent_memlimit) acc)
+      (fun p (id,mostfrequent_timelimit,mostfrequent_steplimit,mostfrequent_memlimit) acc ->
+        Mint.add id (p,mostfrequent_timelimit,mostfrequent_steplimit,mostfrequent_memlimit) acc)
       provers Mint.empty
   in
   Mint.iter (save_prover fmt) provers_to_save;
@@ -936,7 +949,7 @@ type 'a keygen = ?parent:'a -> unit -> 'a
 let add_external_proof
     ?(notify=notify)
     ~(keygen:'a keygen) ~obsolete
-    ~archived ~timelimit ~memlimit ~edit (g:'a goal) p result =
+    ~archived ~timelimit ~steplimit ~memlimit ~edit (g:'a goal) p result =
   assert (edit <> Some "");
   let key = keygen ~parent:g.goal_key () in
   let a = { proof_prover = p;
@@ -946,6 +959,7 @@ let add_external_proof
             proof_archived = archived;
             proof_state = result;
             proof_timelimit = timelimit;
+	    proof_steplimit = steplimit;
             proof_memlimit = memlimit;
             proof_edited_as = edit;
           }
@@ -1168,7 +1182,7 @@ let load_result r =
           match status with
             | "valid" -> Call_provers.Valid
             | "invalid" -> Call_provers.Invalid
-            | "unknown" -> Call_provers.Unknown ""
+            | "unknown" -> Call_provers.Unknown ("", None)
             | "timeout" -> Call_provers.Timeout
             | "outofmemory" -> Call_provers.OutOfMemory
             | "failure" -> Call_provers.Failure ""
@@ -1194,7 +1208,7 @@ let load_result r =
           Call_provers.pr_output = "";
           Call_provers.pr_status = Unix.WEXITED 0;
 	  Call_provers.pr_steps = steps;
-	  Call_provers.pr_model = Model_parser.default_model
+	  Call_provers.pr_model = Model_parser.default_model;
         }
     | "undone" -> Interrupted
     | "unedited" -> Unedited
@@ -1231,7 +1245,7 @@ let load_ident elt =
   Ident.id_register preid
 
 type 'key load_ctxt = {
-  old_provers : (Whyconf.prover * int * int) Mint.t ;
+  old_provers : (Whyconf.prover * int * int * int) Mint.t ;
   keygen : 'key keygen;
 }
 
@@ -1265,7 +1279,7 @@ and load_proof_or_transf ctxt mg a =
         let prover = string_attribute "prover" a in
         try
           let prover = int_of_string prover in
-          let (p,timelimit,memlimit) =Mint.find prover ctxt.old_provers in
+          let (p,timelimit,steplimit,memlimit) =Mint.find prover ctxt.old_provers in
           let res = match a.Xml.elements with
             | [r] -> load_result r
             | [] -> Interrupted
@@ -1278,6 +1292,7 @@ and load_proof_or_transf ctxt mg a =
           let obsolete = bool_attribute "obsolete" a false in
           let archived = bool_attribute "archived" a false in
           let timelimit = int_attribute_def "timelimit" a timelimit in
+	  let steplimit = int_attribute_def "steplimit" a steplimit in
           let memlimit = int_attribute_def "memlimit" a memlimit in
         (*
           if timelimit < 0 then begin
@@ -1289,7 +1304,7 @@ and load_proof_or_transf ctxt mg a =
         *)
           let (_ : 'a proof_attempt) =
             add_external_proof ~keygen:ctxt.keygen ~archived ~obsolete
-              ~timelimit ~memlimit ~edit mg p res
+              ~timelimit ~steplimit ~memlimit ~edit mg p res
           in
           ()
         with Failure _ | Not_found ->
@@ -1476,11 +1491,12 @@ let load_file ~keygen session old_provers f =
             let version = string_attribute "version" f in
             let altern = string_attribute_def "alternative" f "" in
             let timelimit = int_attribute_def "timelimit" f 5 in
+	    let steplimit = int_attribute_def "steplimit" f 1 in
             let memlimit = int_attribute_def "memlimit" f 1000 in
             let p = {C.prover_name = name;
                      prover_version = version;
                      prover_altern = altern} in
-            Mint.add id (p,timelimit,memlimit) old_provers
+            Mint.add id (p,timelimit,steplimit,memlimit) old_provers
           with Failure _ ->
             Warning.emit "[Warning] Session.load_file: unexpected non-numeric prover id '%s'@." id;
             old_provers
@@ -1500,7 +1516,7 @@ let load_session ~keygen session xml =
         List.fold_left (load_file ~keygen session) Mint.empty xml.Xml.elements
       in
       Mint.iter
-        (fun id (p,_,_) ->
+        (fun id (p,_,_,_) ->
           Debug.dprintf debug "prover %d: %a@." id Whyconf.print_prover p;
           PHprover.replace session.session_prover_ids p id)
         old_provers;
@@ -1909,7 +1925,7 @@ let ft_of_pa a =
     But since it will be perhaps removed...
  *)
 let copy_external_proof
-    ?notify ~keygen ?obsolete ?archived ?timelimit ?memlimit ?edit
+    ?notify ~keygen ?obsolete ?archived ?timelimit ?steplimit ?memlimit ?edit
     ?goal ?prover ?attempt_status ?env_session ?session a =
   let session = match env_session with
     | Some eS -> Some eS.session
@@ -1917,6 +1933,7 @@ let copy_external_proof
   let obsolete = Opt.get_def a.proof_obsolete obsolete in
   let archived = Opt.get_def a.proof_archived archived in
   let timelimit = Opt.get_def a.proof_timelimit timelimit in
+  let steplimit = Opt.get_def a.proof_steplimit steplimit in
   let memlimit = Opt.get_def a.proof_memlimit memlimit in
   let pas = Opt.get_def a.proof_state attempt_status in
   let ngoal = Opt.get_def a.proof_parent goal in
@@ -1964,7 +1981,7 @@ let copy_external_proof
             Some (dst_file)
   in
   add_external_proof ?notify ~keygen
-    ~obsolete ~archived ~timelimit ~memlimit ~edit ngoal nprover pas
+    ~obsolete ~archived ~timelimit ~steplimit ~memlimit ~edit ngoal nprover pas
 
 exception UnloadableProver of Whyconf.prover
 
@@ -2021,10 +2038,10 @@ let print_attempt_status fmt = function
   | InternalFailure _ -> pp_print_string fmt "Failure"
 
 let print_external_proof fmt p =
-  fprintf fmt "%a - %a (%i, %i)%s%s%s"
+  fprintf fmt "%a - %a (%i, %i, %i)%s%s%s"
     Whyconf.print_prover p.proof_prover
     print_attempt_status p.proof_state
-    p.proof_timelimit p.proof_memlimit
+    p.proof_timelimit p.proof_steplimit p.proof_memlimit
     (if p.proof_obsolete then " obsolete" else "")
     (if p.proof_archived then " archived" else "")
     (if p.proof_edited_as <> None then " edited" else "")
@@ -2060,6 +2077,7 @@ let merge_proof ~keygen obsolete to_goal _ from_proof =
        ~obsolete
        ~archived:from_proof.proof_archived
        ~timelimit:from_proof.proof_timelimit
+       ~steplimit:from_proof.proof_steplimit
        ~memlimit:from_proof.proof_memlimit
        ~edit:from_proof.proof_edited_as
        to_goal