Merge PR #79: Let the kernel assume that a (co-)inductive type is positive.

13 files changed, 176 insertions, 122 deletions

diff --git a/kernel/declarations.mli b/kernel/declarations.mli
index 1b77d5b7c..8b42a90e4 100644
--- a/kernel/declarations.mli
+++ b/kernel/declarations.mli
@@ -66,6 +66,15 @@ type constant_def =
 
 type constant_universes = Univ.universe_context
 
+(** The [typing_flags] are instructions to the type-checker which
+    modify its behaviour. The typing flags used in the type-checking
+    of a constant are tracked in their {!constant_body} so that they
+    can be displayed to the user. *)
+type typing_flags = {
+  check_guarded : bool; (** If [false] then fixed points and co-fixed
+                            points are assumed to be total. *)
+}
+
 (* some contraints are in constant_constraints, some other may be in
  * the OpaueDef *)
 type constant_body = {
@@ -76,7 +85,11 @@ type constant_body = {
     const_polymorphic : bool; (** Is it polymorphic or not *)
     const_universes : constant_universes;
     const_proj : projection_body option;
-    const_inline_code : bool }
+    const_inline_code : bool;
+    const_typing_flags : typing_flags; (** The typing options which
+                                           were used for
+                                           type-checking. *)
+}
 
 (** {6 Representation of mutual inductive types in the kernel } *)
 
@@ -178,6 +191,7 @@ type mutual_inductive_body = {
 
     mind_private : bool option; (** allow pattern-matching: Some true ok, Some false blocked *)
   
+    mind_checked_positive : bool; (** [false] when the mutual-inductive was assumed to be well-founded, bypassing the positivity checker.  *)
 }
 
 (** {6 Module declarations } *)
diff --git a/kernel/declareops.ml b/kernel/declareops.ml
index a09a8b786..78e2f386e 100644
--- a/kernel/declareops.ml
+++ b/kernel/declareops.ml
@@ -131,7 +131,8 @@ let subst_const_body sub cb =
           Option.map (Cemitcodes.subst_to_patch_subst sub) cb.const_body_code;
         const_polymorphic = cb.const_polymorphic;
         const_universes = cb.const_universes;
-        const_inline_code = cb.const_inline_code }
+        const_inline_code = cb.const_inline_code;
+        const_typing_flags = cb.const_typing_flags }
 
 (** {7 Hash-consing of constants } *)
 
@@ -254,7 +255,9 @@ let subst_mind_body sub mib =
     mind_packets = Array.smartmap (subst_mind_packet sub) mib.mind_packets ;
     mind_polymorphic = mib.mind_polymorphic;
     mind_universes = mib.mind_universes;
-    mind_private = mib.mind_private }
+    mind_private = mib.mind_private;
+    mind_checked_positive = mib.mind_checked_positive;
+  }
 
 let inductive_instance mib =
   if mib.mind_polymorphic then
diff --git a/kernel/entries.mli b/kernel/entries.mli
index d07ca2103..8b29e3abd 100644
--- a/kernel/entries.mli
+++ b/kernel/entries.mli
@@ -51,7 +51,10 @@ type mutual_inductive_entry = {
   mind_entry_inds : one_inductive_entry list;
   mind_entry_polymorphic : bool; 
   mind_entry_universes : Univ.universe_context;
-  mind_entry_private : bool option }
+  mind_entry_private : bool option;
+  mind_entry_check_positivity : bool;
+  (** [false] if positivity is to be assumed. *)
+}
 
 (** {6 Constants (Definition/Axiom) } *)
 type 'a proof_output = constr Univ.in_universe_context_set * 'a
diff --git a/kernel/fast_typeops.ml b/kernel/fast_typeops.ml
index 7f4ba8ecb..35c162cf3 100644
--- a/kernel/fast_typeops.ml
+++ b/kernel/fast_typeops.ml
@@ -327,7 +327,7 @@ let type_fixpoint env lna lar vdef vdeft =
     (* ATTENTION : faudra faire le typage du contexte des Const,
     Ind et Constructsi un jour cela devient des constructions
     arbitraires et non plus des variables *)
-let rec execute env cstr =
+let rec execute ~flags env cstr =
   let open Context.Rel.Declaration in
   match kind_of_term cstr with
     (* Atomic terms *)
@@ -347,12 +347,12 @@ let rec execute env cstr =
       judge_of_constant env c
 	
     | Proj (p, c) ->
-        let ct = execute env c in
+        let ct = execute ~flags env c in
           judge_of_projection env p c ct
 
     (* Lambda calculus operators *)
     | App (f,args) ->
-        let argst = execute_array env args in
+        let argst = execute_array ~flags env args in
 	let ft =
 	  match kind_of_term f with
 	  | Ind ind when Environ.template_polymorphic_pind ind env ->
@@ -365,7 +365,7 @@ let rec execute env cstr =
 	      judge_of_constant_knowing_parameters env cst args
 	  | _ ->
 	    (* Full or no sort-polymorphism *)
-	    execute env f
+            execute ~flags env f
 	in
 
 	  judge_of_apply env f ft args argst
@@ -373,25 +373,25 @@ let rec execute env cstr =
     | Lambda (name,c1,c2) ->
       let _ = execute_is_type env c1 in
       let env1 = push_rel (LocalAssum (name,c1)) env in
-      let c2t = execute env1 c2 in
+      let c2t = execute ~flags env1 c2 in
         judge_of_abstraction env name c1 c2t
 
     | Prod (name,c1,c2) ->
-      let vars = execute_is_type env c1 in
+      let vars = execute_is_type ~flags env c1 in
       let env1 = push_rel (LocalAssum (name,c1)) env in
-      let vars' = execute_is_type env1 c2 in
+      let vars' = execute_is_type ~flags env1 c2 in
 	judge_of_product env name vars vars'
 
     | LetIn (name,c1,c2,c3) ->
-      let c1t = execute env c1 in
+      let c1t = execute ~flags env c1 in
       let _c2s = execute_is_type env c2 in
       let _ = judge_of_cast env c1 c1t DEFAULTcast c2 in
       let env1 = push_rel (LocalDef (name,c1,c2)) env in
-      let c3t = execute env1 c3 in
+      let c3t = execute ~flags env1 c3 in
 	subst1 c1 c3t
 
     | Cast (c,k,t) ->
-      let ct = execute env c in
+      let ct = execute ~flags env c in
       let _ts = execute_type env t in
       let _ = judge_of_cast env c ct k t in
 	t
@@ -404,20 +404,20 @@ let rec execute env cstr =
       judge_of_constructor env c
 
     | Case (ci,p,c,lf) ->
-        let ct = execute env c in
-        let pt = execute env p in
-        let lft = execute_array env lf in
+        let ct = execute ~flags env c in
+        let pt = execute ~flags env p in
+        let lft = execute_array ~flags env lf in
           judge_of_case env ci p pt c ct lf lft
 
     | Fix ((vn,i as vni),recdef) ->
-      let (fix_ty,recdef') = execute_recdef env recdef i in
+      let (fix_ty,recdef') = execute_recdef ~flags env recdef i in
       let fix = (vni,recdef') in
-        check_fix env fix; fix_ty
+        check_fix env ~flags fix; fix_ty
 	  
     | CoFix (i,recdef) ->
-      let (fix_ty,recdef') = execute_recdef env recdef i in
+      let (fix_ty,recdef') = execute_recdef ~flags env recdef i in
       let cofix = (i,recdef') in
-        check_cofix env cofix; fix_ty
+        check_cofix env ~flags cofix; fix_ty
 	  
     (* Partial proofs: unsupported by the kernel *)
     | Meta _ ->
@@ -426,38 +426,41 @@ let rec execute env cstr =
     | Evar _ ->
 	anomaly (Pp.str "the kernel does not support existential variables")
 
-and execute_is_type env constr =
-  let t = execute env constr in
+and execute_is_type ~flags env constr =
+  let t = execute ~flags env constr in
     check_type env constr t
 
-and execute_type env constr =
-  let t = execute env constr in
+and execute_type ~flags env constr =
+  let t = execute ~flags env constr in
     type_judgment env constr t
 
-and execute_recdef env (names,lar,vdef) i =
-  let lart = execute_array env lar in
+and execute_recdef ~flags env (names,lar,vdef) i =
+  let lart = execute_array ~flags env lar in
   let lara = Array.map2 (assumption_of_judgment env) lar lart in
   let env1 = push_rec_types (names,lara,vdef) env in
-  let vdeft = execute_array env1 vdef in
+  let vdeft = execute_array ~flags env1 vdef in
   let () = type_fixpoint env1 names lara vdef vdeft in
     (lara.(i),(names,lara,vdef))
 
-and execute_array env = Array.map (execute env)
+and execute_array ~flags env = Array.map (execute ~flags env)
 
 (* Derived functions *)
-let infer env constr =
-  let t = execute env constr in
+let infer ~flags env constr =
+  let t = execute ~flags env constr in
     make_judge constr t
 
 let infer = 
   if Flags.profile then
     let infer_key = Profile.declare_profile "Fast_infer" in
-      Profile.profile2 infer_key infer
-  else infer
+      Profile.profile3 infer_key (fun a b c -> infer ~flags:a b c)
+  else (fun a b c -> infer ~flags:a b c)
 
-let infer_type env constr =
-  execute_type env constr
+(* Restores the labels of [infer] lost to profiling. *)
+let infer ~flags env t = infer flags env t
 
-let infer_v env cv =
-  let jv = execute_array env cv in
+let infer_type ~flags env constr =
+  execute_type ~flags env constr
+
+let infer_v ~flags env cv =
+  let jv = execute_array ~flags env cv in
     make_judgev cv jv
diff --git a/kernel/fast_typeops.mli b/kernel/fast_typeops.mli
index 05d52b2d3..45a603038 100644
--- a/kernel/fast_typeops.mli
+++ b/kernel/fast_typeops.mli
@@ -8,6 +8,7 @@
 
 open Term
 open Environ
+open Declarations
 
 (** {6 Typing functions (not yet tagged as safe) }
     
@@ -18,6 +19,6 @@ open Environ
  *)
 
 
-val infer      : env -> constr       -> unsafe_judgment
-val infer_v    : env -> constr array -> unsafe_judgment array
-val infer_type : env -> types        -> unsafe_type_judgment
+val infer      : flags:typing_flags -> env -> constr       -> unsafe_judgment
+val infer_v    : flags:typing_flags -> env -> constr array -> unsafe_judgment array
+val infer_type : flags:typing_flags -> env -> types        -> unsafe_type_judgment
diff --git a/kernel/indtypes.ml b/kernel/indtypes.ml
index edb758f07..b74788d21 100644
--- a/kernel/indtypes.ml
+++ b/kernel/indtypes.ml
@@ -483,8 +483,12 @@ let array_min nmr a = if Int.equal nmr 0 then 0 else
     for use by the guard condition (terms at these positions are
     considered sub-terms) as well as the number of of non-uniform
     arguments (used to generate induction schemes, so a priori less
-    relevant to the kernel). *)
-let check_positivity_one recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as ind) nnonrecargs lcnames indlc =
+    relevant to the kernel).
+
+    If [chkpos] is [false] then positivity is assumed, and
+    [check_positivity_one] computes the subterms occurrences in a
+    best-effort fashion. *)
+let check_positivity_one ~chkpos recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as ind) nnonrecargs lcnames indlc =
   let nparamsctxt = Context.Rel.length paramsctxt in
   let nmr = Context.Rel.nhyps paramsctxt in
   (** Positivity of one argument [c] of a constructor (i.e. the
@@ -501,9 +505,12 @@ let check_positivity_one recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as i
                 recursive call. Occurrences in the right-hand side of
                 the product must be strictly positive.*)
             (match weaker_noccur_between env n ntypes b with
-		None -> failwith_non_pos_list n ntypes [b]
+	      | None when chkpos ->
+                  failwith_non_pos_list n ntypes [b]
+              | None ->
+                  check_pos (ienv_push_var ienv (na, b, mk_norec)) nmr d
               | Some b ->
-	          check_pos (ienv_push_var ienv (na, b, mk_norec)) nmr d)
+                  check_pos (ienv_push_var ienv (na, b, mk_norec)) nmr d)
 	| Rel k ->
             (try let (ra,rarg) = List.nth ra_env (k-1) in
             let largs = List.map (whd_betadeltaiota env) largs in
@@ -515,7 +522,8 @@ let check_positivity_one recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as i
               (** The case where one of the inductives of the mutually
                   inductive block occurs as an argument of another is not
                   known to be safe. So Coq rejects it. *)
-	      if not (List.for_all (noccur_between n ntypes) largs)
+	      if chkpos &&
+                 not (List.for_all (noccur_between n ntypes) largs)
 	      then failwith_non_pos_list n ntypes largs
 	      else (nmr1,rarg)
               with Failure _ | Invalid_argument _ -> (nmr,mk_norec))
@@ -530,8 +538,9 @@ let check_positivity_one recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as i
             (** If an inductive of the mutually inductive block
                 appears in any other way, then the positivy check gives
                 up. *)
-	    if noccur_between n ntypes x &&
-              List.for_all (noccur_between n ntypes) largs
+	    if not chkpos ||
+              (noccur_between n ntypes x &&
+               List.for_all (noccur_between n ntypes) largs)
 	    then (nmr,mk_norec)
 	    else failwith_non_pos_list n ntypes (x::largs)
 
@@ -553,7 +562,7 @@ let check_positivity_one recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as i
       (** Inductives of the inductive block being defined are only
           allowed to appear nested in the parameters of another inductive
           type. Not in the proper indices. *)
-      if not (List.for_all (noccur_between n ntypes) auxnonrecargs) then
+      if chkpos && not (List.for_all (noccur_between n ntypes) auxnonrecargs) then
 	failwith_non_pos_list n ntypes auxnonrecargs;
       (* Nested mutual inductive types are not supported *)
       let auxntyp = mib.mind_ntypes in
@@ -613,7 +622,8 @@ let check_positivity_one recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as i
                 | _ -> raise (IllFormedInd (LocalNotConstructor(paramsctxt,nnonrecargs)))
                 end
               else
-                if not (List.for_all (noccur_between n ntypes) largs)
+                if chkpos &&
+                   not (List.for_all (noccur_between n ntypes) largs)
                 then failwith_non_pos_list n ntypes largs
             in
             (nmr, List.rev lrec)
@@ -633,9 +643,13 @@ let check_positivity_one recursive (env,_,ntypes,_ as ienv) paramsctxt (_,i as i
   and nmr' = array_min nmr irecargs_nmr
   in (nmr', mk_paths (Mrec ind) irecargs)
 
-(** [check_positivity kn env_ar paramsctxt inds] checks that the mutually
-    inductive block [inds] is strictly positive. *)
-let check_positivity kn env_ar_par paramsctxt finite inds =
+(** [check_positivity ~chkpos kn env_ar paramsctxt inds] checks that the mutually
+    inductive block [inds] is strictly positive.
+
+    If [chkpos] is [false] then positivity is assumed, and
+    [check_positivity_one] computes the subterms occurrences in a
+    best-effort fashion. *)
+let check_positivity ~chkpos kn env_ar_par paramsctxt finite inds =
   let ntypes = Array.length inds in
   let recursive = finite != Decl_kinds.BiFinite in
   let rc = Array.mapi (fun j t -> (Mrec (kn,j),t)) (Rtree.mk_rec_calls ntypes) in
@@ -647,7 +661,7 @@ let check_positivity kn env_ar_par paramsctxt finite inds =
       List.init nparamsctxt (fun _ -> (Norec,mk_norec)) @ ra_env_ar in
     let ienv = (env_ar_par, 1+nparamsctxt, ntypes, ra_env_ar_par) in
     let nnonrecargs = Context.Rel.nhyps sign - nmr in
-    check_positivity_one recursive ienv paramsctxt (kn,i) nnonrecargs lcnames lc
+    check_positivity_one ~chkpos recursive ienv paramsctxt (kn,i) nnonrecargs lcnames lc
   in
   let irecargs_nmr = Array.mapi check_one inds in
   let irecargs = Array.map snd irecargs_nmr
@@ -802,7 +816,7 @@ let compute_projections ((kn, _ as ind), u as indu) n x nparamargs params
     Array.of_list (List.rev kns),
     Array.of_list (List.rev pbs)
 
-let build_inductive env p prv ctx env_ar paramsctxt kn isrecord isfinite inds nmr recargs =
+let build_inductive env p prv ctx env_ar paramsctxt kn isrecord isfinite inds nmr recargs is_checked =
   let ntypes = Array.length inds in
   (* Compute the set of used section variables *)
   let hyps = used_section_variables env inds in
@@ -908,6 +922,7 @@ let build_inductive env p prv ctx env_ar paramsctxt kn isrecord isfinite inds nm
       mind_polymorphic = p;
       mind_universes = ctx;
       mind_private = prv;
+      mind_checked_positive = is_checked;
     }
 
 (************************************************************************)
@@ -916,10 +931,11 @@ let build_inductive env p prv ctx env_ar paramsctxt kn isrecord isfinite inds nm
 let check_inductive env kn mie =
   (* First type-check the inductive definition *)
   let (env_ar, env_ar_par, paramsctxt, inds) = typecheck_inductive env mie in
+  let chkpos = mie.mind_entry_check_positivity in
   (* Then check positivity conditions *)
-  let (nmr,recargs) = check_positivity kn env_ar_par paramsctxt mie.mind_entry_finite inds in
+  let (nmr,recargs) = check_positivity ~chkpos kn env_ar_par paramsctxt mie.mind_entry_finite inds in
   (* Build the inductive packets *)
     build_inductive env mie.mind_entry_polymorphic mie.mind_entry_private
       mie.mind_entry_universes
       env_ar paramsctxt kn mie.mind_entry_record mie.mind_entry_finite
-      inds nmr recargs
+      inds nmr recargs chkpos
diff --git a/kernel/inductive.ml b/kernel/inductive.ml
index 499cbf0df..24bdaa5c4 100644
--- a/kernel/inductive.ml
+++ b/kernel/inductive.ml
@@ -1067,21 +1067,24 @@ let inductive_of_mutfix env ((nvect,bodynum),(names,types,bodies as recdef)) =
   (Array.map fst rv, Array.map snd rv)
 
 
-let check_fix env ((nvect,_),(names,_,bodies as recdef) as fix) =
-  let (minds, rdef) = inductive_of_mutfix env fix in
-  let get_tree (kn,i) =
-    let mib = Environ.lookup_mind kn env in
-    mib.mind_packets.(i).mind_recargs
-  in
-  let trees = Array.map (fun (mind,_) -> get_tree mind) minds in
-  for i = 0 to Array.length bodies - 1 do
-    let (fenv,body) = rdef.(i) in
-    let renv = make_renv fenv nvect.(i) trees.(i) in
-    try check_one_fix renv nvect trees body
-    with FixGuardError (fixenv,err) ->
-      error_ill_formed_rec_body fixenv err names i
-	(push_rec_types recdef env) (judgment_of_fixpoint recdef)
-  done
+let check_fix env ~flags ((nvect,_),(names,_,bodies as recdef) as fix) =
+  if flags.check_guarded then
+    let (minds, rdef) = inductive_of_mutfix env fix in
+    let get_tree (kn,i) =
+      let mib = Environ.lookup_mind kn env in
+      mib.mind_packets.(i).mind_recargs
+    in
+    let trees = Array.map (fun (mind,_) -> get_tree mind) minds in
+    for i = 0 to Array.length bodies - 1 do
+      let (fenv,body) = rdef.(i) in
+      let renv = make_renv fenv nvect.(i) trees.(i) in
+      try check_one_fix renv nvect trees body
+      with FixGuardError (fixenv,err) ->
+        error_ill_formed_rec_body fixenv err names i
+	  (push_rec_types recdef env) (judgment_of_fixpoint recdef)
+    done
+  else
+    ()
 
 (*
 let cfkey = Profile.declare_profile "check_fix";;
@@ -1192,12 +1195,15 @@ let check_one_cofix env nbfix def deftype =
 (* The  function which checks that the whole block of definitions
    satisfies the guarded condition *)
 
-let check_cofix env (bodynum,(names,types,bodies as recdef)) =
-  let nbfix = Array.length bodies in
-  for i = 0 to nbfix-1 do
-    let fixenv = push_rec_types recdef env in
-    try check_one_cofix fixenv nbfix bodies.(i) types.(i)
-    with CoFixGuardError (errenv,err) ->
-      error_ill_formed_rec_body errenv err names i
-	fixenv (judgment_of_fixpoint recdef)
-  done
+let check_cofix env ~flags (bodynum,(names,types,bodies as recdef)) =
+  if flags.check_guarded then
+    let nbfix = Array.length bodies in
+    for i = 0 to nbfix-1 do
+      let fixenv = push_rec_types recdef env in
+      try check_one_cofix fixenv nbfix bodies.(i) types.(i)
+      with CoFixGuardError (errenv,err) ->
+        error_ill_formed_rec_body errenv err names i
+	  fixenv (judgment_of_fixpoint recdef)
+    done
+  else
+    ()
diff --git a/kernel/inductive.mli b/kernel/inductive.mli
index c0d18bc6e..25a557472 100644
--- a/kernel/inductive.mli
+++ b/kernel/inductive.mli
@@ -94,8 +94,11 @@ val inductive_sort_family : one_inductive_body -> sorts_family
 val check_case_info : env -> pinductive -> case_info -> unit
 
 (** {6 Guard conditions for fix and cofix-points. } *)
-val check_fix : env -> fixpoint -> unit
-val check_cofix : env -> cofixpoint -> unit
+
+(** When [chk] is false, the guard condition is not actually
+    checked. *)
+val check_fix : env -> flags:typing_flags -> fixpoint -> unit
+val check_cofix : env -> flags:typing_flags -> cofixpoint -> unit
 
 (** {6 Support for sort-polymorphic inductive types } *)
 
diff --git a/kernel/safe_typing.ml b/kernel/safe_typing.ml
index ce05190b6..72d6ee518 100644
--- a/kernel/safe_typing.ml
+++ b/kernel/safe_typing.ml
@@ -373,8 +373,8 @@ let safe_push_named d env =
   Environ.push_named d env
 
 
-let push_named_def (id,de) senv =
-  let c,typ,univs = Term_typing.translate_local_def senv.revstruct senv.env id de in
+let push_named_def ~flags (id,de) senv =
+  let c,typ,univs = Term_typing.translate_local_def ~flags senv.revstruct senv.env id de in
   let poly = de.Entries.const_entry_polymorphic in
   let univs = Univ.ContextSet.of_context univs in
   let c, univs = match c with
@@ -388,9 +388,9 @@ let push_named_def (id,de) senv =
   let env'' = safe_push_named (LocalDef (id,c,typ)) senv'.env in
     univs, {senv' with env=env''}
 
-let push_named_assum ((id,t,poly),ctx) senv =
+let push_named_assum ~flags ((id,t,poly),ctx) senv =
   let senv' = push_context_set poly ctx senv in
-  let t = Term_typing.translate_local_assum senv'.env t in
+  let t = Term_typing.translate_local_assum ~flags senv'.env t in
   let env'' = safe_push_named (LocalAssum (id,t)) senv'.env in
     {senv' with env=env''}
 
@@ -479,7 +479,7 @@ let update_resolver f senv = { senv with modresolver = f senv.modresolver }
 
 (** Insertion of constants and parameters in environment *)
 type global_declaration =
-  | ConstantEntry of bool * private_constants Entries.constant_entry
+  | ConstantEntry of bool * private_constants Entries.constant_entry * Declarations.typing_flags
   | GlobalRecipe of Cooking.recipe
 
 type exported_private_constant = 
@@ -512,10 +512,10 @@ let add_constant dir l decl senv =
   let no_section = DirPath.is_empty dir in
   let seff_to_export, decl =
     match decl with
-    | ConstantEntry (true, ce) ->
+    | ConstantEntry (true, ce, flags) ->
         let exports, ce =
-          Term_typing.export_side_effects senv.revstruct senv.env ce in
-        exports, ConstantEntry (false, ce)
+          Term_typing.export_side_effects ~flags senv.revstruct senv.env ce in
+        exports, ConstantEntry (false, ce, flags)
     | _ -> [], decl
   in
   let senv =
@@ -524,8 +524,8 @@ let add_constant dir l decl senv =
   let senv =
     let cb = 
       match decl with
-      | ConstantEntry (export_seff,ce) ->
-        Term_typing.translate_constant senv.revstruct senv.env kn ce
+      | ConstantEntry (export_seff,ce,flags) ->
+        Term_typing.translate_constant ~flags senv.revstruct senv.env kn ce
       | GlobalRecipe r ->
         let cb = Term_typing.translate_recipe senv.env kn r in
         if no_section then Declareops.hcons_const_body cb else cb in
diff --git a/kernel/safe_typing.mli b/kernel/safe_typing.mli
index 71dac321f..b614a368c 100644
--- a/kernel/safe_typing.mli
+++ b/kernel/safe_typing.mli
@@ -77,19 +77,21 @@ val is_joined_environment : safe_environment -> bool
 (** Insertion of local declarations (Local or Variables) *)
 
 val push_named_assum :
+  flags:Declarations.typing_flags ->
   (Id.t * Term.types * bool (* polymorphic *))
     Univ.in_universe_context_set -> safe_transformer0
 
 (** Returns the full universe context necessary to typecheck the definition
   (futures are forced) *)
 val push_named_def :
+  flags:Declarations.typing_flags ->
   Id.t * private_constants Entries.definition_entry -> Univ.universe_context_set safe_transformer
 
 (** Insertion of global axioms or definitions *)
 
 type global_declaration =
                   (* bool: export private constants *)
-  | ConstantEntry of bool * private_constants Entries.constant_entry
+  | ConstantEntry of bool * private_constants Entries.constant_entry * Declarations.typing_flags
   | GlobalRecipe of Cooking.recipe
 
 type exported_private_constant = 
diff --git a/kernel/term_typing.ml b/kernel/term_typing.ml
index 6bfd2457a..8d74dc390 100644
--- a/kernel/term_typing.ml
+++ b/kernel/term_typing.ml
@@ -22,18 +22,18 @@ open Entries
 open Typeops
 open Fast_typeops
 
-let constrain_type env j poly subst = function
+let constrain_type ~flags env j poly subst = function
   | `None -> 
     if not poly then (* Old-style polymorphism *)
       make_polymorphic_if_constant_for_ind env j
     else RegularArity (Vars.subst_univs_level_constr subst j.uj_type)
   | `Some t ->
-      let tj = infer_type env t in
+      let tj = infer_type ~flags env t in
       let _ = judge_of_cast env j DEFAULTcast tj in
 	assert (eq_constr t tj.utj_val);
 	RegularArity (Vars.subst_univs_level_constr subst t)
   | `SomeWJ (t, tj) ->
-      let tj = infer_type env t in
+      let tj = infer_type ~flags env t in
       let _ = judge_of_cast env j DEFAULTcast tj in
 	assert (eq_constr t tj.utj_val);
 	RegularArity (Vars.subst_univs_level_constr subst t)
@@ -171,11 +171,11 @@ let feedback_completion_typecheck =
   Option.iter (fun state_id ->
       feedback ~id:(State state_id) Feedback.Complete)
 
-let infer_declaration ~trust env kn dcl =
+let infer_declaration ~flags ~trust env kn dcl =
   match dcl with
   | ParameterEntry (ctx,poly,(t,uctx),nl) ->
       let env = push_context ~strict:(not poly) uctx env in
-      let j = infer env t in
+      let j = infer ~flags env t in
       let abstract = poly && not (Option.is_empty kn) in
       let usubst, univs = Univ.abstract_universes abstract uctx in
       let c = Typeops.assumption_of_judgment env j in
@@ -196,7 +196,7 @@ let infer_declaration ~trust env kn dcl =
 	  let env' = push_context_set uctx env in
           let j =
             let body,env',ectx = skip_trusted_seff valid_signatures body env' in
-            let j = infer env' body in
+            let j = infer ~flags env' body in
             unzip ectx j in
           let j = hcons_j j in
 	  let subst = Univ.LMap.empty in
@@ -220,8 +220,8 @@ let infer_declaration ~trust env kn dcl =
       let abstract = c.const_entry_polymorphic && not (Option.is_empty kn) in
       let usubst, univs =
 	Univ.abstract_universes abstract (Univ.ContextSet.to_context ctx) in      
-      let j = infer env body in
-      let typ = constrain_type env j c.const_entry_polymorphic usubst (map_option_typ typ) in
+      let j = infer ~flags env body in
+      let typ = constrain_type ~flags env j c.const_entry_polymorphic usubst (map_option_typ typ) in
       let def = hcons_constr (Vars.subst_univs_level_constr usubst j.uj_val) in
       let def = 
 	if opaque then OpaqueDef (Opaqueproof.create (Future.from_val (def, Univ.ContextSet.empty)))
@@ -268,7 +268,7 @@ let record_aux env s_ty s_bo suggested_expr =
 let suggest_proof_using = ref (fun _ _ _ _ _ -> "")
 let set_suggest_proof_using f = suggest_proof_using := f
 
-let build_constant_declaration kn env (def,typ,proj,poly,univs,inline_code,ctx) =
+let build_constant_declaration ~flags kn env (def,typ,proj,poly,univs,inline_code,ctx) =
   let open Context.Named.Declaration in
   let check declared inferred =
     let mk_set l = List.fold_right Id.Set.add (List.map get_id l) Id.Set.empty in
@@ -352,7 +352,9 @@ let build_constant_declaration kn env (def,typ,proj,poly,univs,inline_code,ctx)
 	    const_body_code = None;
 	    const_polymorphic = poly;
 	    const_universes = univs;
-	    const_inline_code = inline_code }
+	    const_inline_code = inline_code;
+	    const_typing_flags = flags;
+	    }
 	in
 	let env = add_constant kn cb env in
 	compile_constant_body env comp_univs def
@@ -365,13 +367,14 @@ let build_constant_declaration kn env (def,typ,proj,poly,univs,inline_code,ctx)
     const_body_code = tps;
     const_polymorphic = poly;
     const_universes = univs;
-    const_inline_code = inline_code }
+    const_inline_code = inline_code;
+    const_typing_flags = flags }
 
 (*s Global and local constant declaration. *)
 
-let translate_constant mb env kn ce =
-  build_constant_declaration kn env
-    (infer_declaration ~trust:mb env (Some kn) ce)
+let translate_constant ~flags mb env kn ce =
+  build_constant_declaration ~flags kn env
+    (infer_declaration ~flags ~trust:mb env (Some kn) ce)
 
 let constant_entry_of_side_effect cb u =
   let pt =
@@ -406,7 +409,7 @@ type side_effect_role =
 type exported_side_effect = 
   constant * constant_body * side_effects constant_entry * side_effect_role
 
-let export_side_effects mb env ce =
+let export_side_effects ~flags mb env ce =
   match ce with
   | ParameterEntry _ | ProjectionEntry _ -> [], ce
   | DefinitionEntry c ->
@@ -447,7 +450,7 @@ let export_side_effects mb env ce =
            let env, cbs =
              List.fold_left (fun (env,cbs) (kn, ocb, u, r) ->
                let ce = constant_entry_of_side_effect ocb u in
-               let cb = translate_constant mb env kn ce in
+               let cb = translate_constant ~flags mb env kn ce in
                (push_seff env (kn, cb,`Nothing, Subproof),(kn,cb,ce,r) :: cbs)) 
              (env,[]) cbs in
            translate_seff sl rest (cbs @ acc) env
@@ -462,17 +465,17 @@ let export_side_effects mb env ce =
        translate_seff trusted seff [] env
 ;;
 
-let translate_local_assum env t =
-  let j = infer env t in
+let translate_local_assum ~flags env t =
+  let j = infer ~flags env t in
   let t = Typeops.assumption_of_judgment env j in
     t
 
 let translate_recipe env kn r =
-  build_constant_declaration kn env (Cooking.cook_constant env r)
+  build_constant_declaration ~flags:{check_guarded=true} kn env (Cooking.cook_constant env r)
 
-let translate_local_def mb env id centry =
+let translate_local_def ~flags mb env id centry =
   let def,typ,proj,poly,univs,inline_code,ctx =
-    infer_declaration ~trust:mb env None (DefinitionEntry centry) in
+    infer_declaration ~flags ~trust:mb env None (DefinitionEntry centry) in
   let typ = type_of_constant_type env typ in
   if ctx = None && !Flags.compilation_mode = Flags.BuildVo then begin
     match def with
diff --git a/kernel/term_typing.mli b/kernel/term_typing.mli
index fcd95576c..b635f2d31 100644
--- a/kernel/term_typing.mli
+++ b/kernel/term_typing.mli
@@ -12,10 +12,10 @@ open Environ
 open Declarations
 open Entries
 
-val translate_local_def : structure_body -> env -> Id.t -> side_effects definition_entry ->
+val translate_local_def : flags:typing_flags -> structure_body -> env -> Id.t -> side_effects definition_entry ->
   constant_def * types * constant_universes
 
-val translate_local_assum : env -> types -> types
+val translate_local_assum : flags:typing_flags -> env -> types -> types
 
 val mk_pure_proof : constr -> side_effects proof_output
 
@@ -32,7 +32,7 @@ val inline_entry_side_effects :
 val uniq_seff : side_effects -> side_effects
 
 val translate_constant :
-  structure_body -> env -> constant -> side_effects constant_entry ->
+  flags:typing_flags -> structure_body -> env -> constant -> side_effects constant_entry ->
     constant_body
 
 type side_effect_role =
@@ -47,7 +47,7 @@ type exported_side_effect =
  * be pushed in the safe_env by safe typing.  The main constant entry
  * needs to be translated as usual after this step. *)
 val export_side_effects :
-  structure_body -> env -> side_effects constant_entry ->
+  flags:typing_flags -> structure_body -> env -> side_effects constant_entry ->
     exported_side_effect list * side_effects constant_entry
 
 val constant_entry_of_side_effect :
@@ -60,11 +60,11 @@ val translate_recipe : env -> constant -> Cooking.recipe -> constant_body
 
 (** Internal functions, mentioned here for debug purpose only *)
 
-val infer_declaration : trust:structure_body -> env -> constant option -> 
+val infer_declaration : flags:typing_flags -> trust:structure_body -> env -> constant option -> 
   side_effects constant_entry -> Cooking.result
 
 val build_constant_declaration :
-  constant -> env -> Cooking.result -> constant_body
+  flags:typing_flags -> constant -> env -> Cooking.result -> constant_body
 
 val set_suggest_proof_using :
   (string -> env -> Id.Set.t -> Id.Set.t -> Id.t list -> string) -> unit
diff --git a/kernel/typeops.ml b/kernel/typeops.ml
index 0ea68e2bc..a94a049df 100644
--- a/kernel/typeops.ml
+++ b/kernel/typeops.ml
@@ -500,13 +500,13 @@ let rec execute env cstr =
     | Fix ((vn,i as vni),recdef) ->
       let (fix_ty,recdef') = execute_recdef env recdef i in
       let fix = (vni,recdef') in
-        check_fix env fix;
+        check_fix ~flags:{check_guarded=true} env fix;
 	make_judge (mkFix fix) fix_ty
 	  
     | CoFix (i,recdef) ->
       let (fix_ty,recdef') = execute_recdef env recdef i in
       let cofix = (i,recdef') in
-        check_cofix env cofix;
+        check_cofix ~flags:{check_guarded=true} env cofix;
 	(make_judge (mkCoFix cofix) fix_ty)
 	  
     (* Partial proofs: unsupported by the kernel *)