(************************************************************************) (* v * The Coq Proof Assistant / The Coq Development Team *) (* 1=List.length l) possible_indexes then let indexes = Array.of_list (List.map List.hd possible_indexes) in let fix = ((indexes, 0),fixdefs) in (try check_fix env fix with | e -> if loc = dummy_loc then raise e else Stdpp.raise_with_loc loc e); indexes else (* we now search recursively amoungst all combinations *) (try List.iter (fun l -> let indexes = Array.of_list l in let fix = ((indexes, 0),fixdefs) in try check_fix env fix; raise (Found indexes) with TypeError _ -> ()) (list_combinations possible_indexes); let errmsg = "Cannot guess decreasing argument of fix." in if loc = dummy_loc then error errmsg else user_err_loc (loc,"search_guard", Pp.str errmsg) with Found indexes -> indexes) (* To embed constr in rawconstr *) let ((constr_in : constr -> Dyn.t), (constr_out : Dyn.t -> constr)) = create "constr" (** Miscellaneous interpretation functions *) let interp_sort = function | RProp c -> Prop c | RType _ -> new_Type_sort () let interp_elimination_sort = function | RProp Null -> InProp | RProp Pos -> InSet | RType _ -> InType module type S = sig module Cases : Cases.S (* Allow references to syntaxically inexistent variables (i.e., if applied on an inductive) *) val allow_anonymous_refs : bool ref (* Generic call to the interpreter from rawconstr to open_constr, leaving unresolved holes as evars and returning the typing contexts of these evars. Work as [understand_gen] for the rest. *) val understand_tcc : ?resolve_classes:bool -> evar_map -> env -> ?expected_type:types -> rawconstr -> open_constr val understand_tcc_evars : evar_defs ref -> env -> typing_constraint -> rawconstr -> constr (* More general entry point with evars from ltac *) (* Generic call to the interpreter from rawconstr to constr, failing unresolved holes in the rawterm cannot be instantiated. In [understand_ltac sigma env ltac_env constraint c], sigma : initial set of existential variables (typically dependent subgoals) ltac_env : partial substitution of variables (used for the tactic language) constraint : tell if interpreted as a possibly constrained term or a type *) val understand_ltac : evar_map -> env -> var_map * unbound_ltac_var_map -> typing_constraint -> rawconstr -> evar_defs * constr (* Standard call to get a constr from a rawconstr, resolving implicit args *) val understand : evar_map -> env -> ?expected_type:Term.types -> rawconstr -> constr (* Idem but the rawconstr is intended to be a type *) val understand_type : evar_map -> env -> rawconstr -> constr (* A generalization of the two previous case *) val understand_gen : typing_constraint -> evar_map -> env -> rawconstr -> constr (* Idem but returns the judgment of the understood term *) val understand_judgment : evar_map -> env -> rawconstr -> unsafe_judgment (* Idem but do not fail on unresolved evars *) val understand_judgment_tcc : evar_defs ref -> env -> rawconstr -> unsafe_judgment (*i*) (* Internal of Pretyping... * Unused outside, but useful for debugging *) val pretype : type_constraint -> env -> evar_defs ref -> var_map * (identifier * identifier option) list -> rawconstr -> unsafe_judgment val pretype_type : val_constraint -> env -> evar_defs ref -> var_map * (identifier * identifier option) list -> rawconstr -> unsafe_type_judgment val pretype_gen : evar_defs ref -> env -> var_map * (identifier * identifier option) list -> typing_constraint -> rawconstr -> constr (*i*) end module Pretyping_F (Coercion : Coercion.S) = struct module Cases = Cases.Cases_F(Coercion) (* Allow references to syntaxically inexistent variables (i.e., if applied on an inductive) *) let allow_anonymous_refs = ref false let evd_comb0 f evdref = let (evd',x) = f !evdref in evdref := evd'; x let evd_comb1 f evdref x = let (evd',y) = f !evdref x in evdref := evd'; y let evd_comb2 f evdref x y = let (evd',z) = f !evdref x y in evdref := evd'; z let evd_comb3 f evdref x y z = let (evd',t) = f !evdref x y z in evdref := evd'; t let mt_evd = Evd.empty (* Utilisé pour inférer le prédicat des Cases *) (* Semble exagérement fort *) (* Faudra préférer une unification entre les types de toutes les clauses *) (* et autoriser des ? à rester dans le résultat de l'unification *) let evar_type_fixpoint loc env evdref lna lar vdefj = let lt = Array.length vdefj in if Array.length lar = lt then for i = 0 to lt-1 do if not (e_cumul env evdref (vdefj.(i)).uj_type (lift lt lar.(i))) then error_ill_typed_rec_body_loc loc env (evars_of !evdref) i lna vdefj lar done let check_branches_message loc env evdref c (explft,lft) = for i = 0 to Array.length explft - 1 do if not (e_cumul env evdref lft.(i) explft.(i)) then let sigma = evars_of !evdref in error_ill_formed_branch_loc loc env sigma c i lft.(i) explft.(i) done (* coerce to tycon if any *) let inh_conv_coerce_to_tycon loc env evdref j = function | None -> j | Some t -> evd_comb2 (Coercion.inh_conv_coerce_to loc env) evdref j t let push_rels vars env = List.fold_right push_rel vars env (* used to enforce a name in Lambda when the type constraints itself is named, hence possibly dependent *) let orelse_name name name' = match name with | Anonymous -> name' | _ -> name let pretype_id loc env (lvar,unbndltacvars) id = try let (n,typ) = lookup_rel_id id (rel_context env) in { uj_val = mkRel n; uj_type = lift n typ } with Not_found -> try List.assoc id lvar with Not_found -> try let (_,_,typ) = lookup_named id env in { uj_val = mkVar id; uj_type = typ } with Not_found -> try (* To build a nicer ltac error message *) match List.assoc id unbndltacvars with | None -> user_err_loc (loc,"", str "Variable " ++ pr_id id ++ str " should be bound to a term.") | Some id0 -> Pretype_errors.error_var_not_found_loc loc id0 with Not_found -> error_var_not_found_loc loc id (* make a dependent predicate from an undependent one *) let make_dep_of_undep env (IndType (indf,realargs)) pj = let n = List.length realargs in let rec decomp n p = if n=0 then p else match kind_of_term p with | Lambda (_,_,c) -> decomp (n-1) c | _ -> decomp (n-1) (applist (lift 1 p, [mkRel 1])) in let sign,s = decompose_prod_n n pj.uj_type in let ind = build_dependent_inductive env indf in let s' = mkProd (Anonymous, ind, s) in let ccl = lift 1 (decomp n pj.uj_val) in let ccl' = mkLambda (Anonymous, ind, ccl) in {uj_val=lam_it ccl' sign; uj_type=prod_it s' sign} let evar_kind_of_term sigma c = kind_of_term (whd_evar (Evd.evars_of sigma) c) (*************************************************************************) (* Main pretyping function *) let pretype_ref evdref env ref = let c = constr_of_global ref in make_judge c (Retyping.get_type_of env Evd.empty c) let pretype_sort = function | RProp c -> judge_of_prop_contents c | RType _ -> judge_of_new_Type () exception Found of fixpoint (* [pretype tycon env evdref lvar lmeta cstr] attempts to type [cstr] *) (* in environment [env], with existential variables [evdref] and *) (* the type constraint tycon *) let rec pretype (tycon : type_constraint) env evdref lvar = function | RRef (loc,ref) -> inh_conv_coerce_to_tycon loc env evdref (pretype_ref evdref env ref) tycon | RVar (loc, id) -> inh_conv_coerce_to_tycon loc env evdref (pretype_id loc env lvar id) tycon | REvar (loc, evk, instopt) -> (* Ne faudrait-il pas s'assurer que hyps est bien un sous-contexte du contexte courant, et qu'il n'y a pas de Rel "caché" *) let hyps = evar_filtered_context (Evd.find (evars_of !evdref) evk) in let args = match instopt with | None -> instance_from_named_context hyps | Some inst -> failwith "Evar subtitutions not implemented" in let c = mkEvar (evk, args) in let j = (Retyping.get_judgment_of env (evars_of !evdref) c) in inh_conv_coerce_to_tycon loc env evdref j tycon | RPatVar (loc,(someta,n)) -> anomaly "Found a pattern variable in a rawterm to type" | RHole (loc,k) -> let ty = match tycon with | Some (None, ty) -> ty | None | Some _ -> e_new_evar evdref env ~src:(loc,InternalHole) (new_Type ()) in { uj_val = e_new_evar evdref env ~src:(loc,k) ty; uj_type = ty } | RRec (loc,fixkind,names,bl,lar,vdef) -> let rec type_bl env ctxt = function [] -> ctxt | (na,bk,None,ty)::bl -> let ty' = pretype_type empty_valcon env evdref lvar ty in let dcl = (na,None,ty'.utj_val) in type_bl (push_rel dcl env) (add_rel_decl dcl ctxt) bl | (na,bk,Some bd,ty)::bl -> let ty' = pretype_type empty_valcon env evdref lvar ty in let bd' = pretype (mk_tycon ty'.utj_val) env evdref lvar ty in let dcl = (na,Some bd'.uj_val,ty'.utj_val) in type_bl (push_rel dcl env) (add_rel_decl dcl ctxt) bl in let ctxtv = Array.map (type_bl env empty_rel_context) bl in let larj = array_map2 (fun e ar -> pretype_type empty_valcon (push_rel_context e env) evdref lvar ar) ctxtv lar in let lara = Array.map (fun a -> a.utj_val) larj in let ftys = array_map2 (fun e a -> it_mkProd_or_LetIn a e) ctxtv lara in let nbfix = Array.length lar in let names = Array.map (fun id -> Name id) names in (* Note: bodies are not used by push_rec_types, so [||] is safe *) let newenv = push_rec_types (names,ftys,[||]) env in let vdefj = array_map2_i (fun i ctxt def -> (* we lift nbfix times the type in tycon, because of * the nbfix variables pushed to newenv *) let (ctxt,ty) = decompose_prod_n_assum (rel_context_length ctxt) (lift nbfix ftys.(i)) in let nenv = push_rel_context ctxt newenv in let j = pretype (mk_tycon ty) nenv evdref lvar def in { uj_val = it_mkLambda_or_LetIn j.uj_val ctxt; uj_type = it_mkProd_or_LetIn j.uj_type ctxt }) ctxtv vdef in evar_type_fixpoint loc env evdref names ftys vdefj; let ftys = Array.map (nf_evar (evars_of !evdref)) ftys in let fdefs = Array.map (fun x -> nf_evar (evars_of !evdref) (j_val x)) vdefj in let fixj = match fixkind with | RFix (vn,i) -> (* First, let's find the guard indexes. *) (* If recursive argument was not given by user, we try all args. An earlier approach was to look only for inductive arguments, but doing it properly involves delta-reduction, and it finally doesn't seem worth the effort (except for huge mutual fixpoints ?) *) let possible_indexes = Array.to_list (Array.mapi (fun i (n,_) -> match n with | Some n -> [n] | None -> list_map_i (fun i _ -> i) 0 ctxtv.(i)) vn) in let fixdecls = (names,ftys,fdefs) in let indexes = search_guard loc env possible_indexes fixdecls in make_judge (mkFix ((indexes,i),fixdecls)) ftys.(i) | RCoFix i -> let cofix = (i,(names,ftys,fdefs)) in (try check_cofix env cofix with e -> Stdpp.raise_with_loc loc e); make_judge (mkCoFix cofix) ftys.(i) in inh_conv_coerce_to_tycon loc env evdref fixj tycon | RSort (loc,s) -> inh_conv_coerce_to_tycon loc env evdref (pretype_sort s) tycon | RApp (loc,f,args) -> let fj = pretype empty_tycon env evdref lvar f in let floc = loc_of_rawconstr f in let rec apply_rec env n resj = function | [] -> resj | c::rest -> let argloc = loc_of_rawconstr c in let resj = evd_comb1 (Coercion.inh_app_fun env) evdref resj in let resty = whd_betadeltaiota env (evars_of !evdref) resj.uj_type in match kind_of_term resty with | Prod (na,c1,c2) -> let hj = pretype (mk_tycon c1) env evdref lvar c in let value, typ = applist (j_val resj, [j_val hj]), subst1 hj.uj_val c2 in apply_rec env (n+1) { uj_val = value; uj_type = typ } rest | _ -> let hj = pretype empty_tycon env evdref lvar c in error_cant_apply_not_functional_loc (join_loc floc argloc) env (evars_of !evdref) resj [hj] in let resj = apply_rec env 1 fj args in let resj = match evar_kind_of_term !evdref resj.uj_val with | App (f,args) -> let f = whd_evar (Evd.evars_of !evdref) f in begin match kind_of_term f with | Ind _ | Const _ when isInd f or has_polymorphic_type (destConst f) -> let sigma = evars_of !evdref in let c = mkApp (f,Array.map (whd_evar sigma) args) in let t = Retyping.get_type_of env sigma c in make_judge c t | _ -> resj end | _ -> resj in inh_conv_coerce_to_tycon loc env evdref resj tycon | RLambda(loc,name,bk,c1,c2) -> let (name',dom,rng) = evd_comb1 (split_tycon loc env) evdref tycon in let dom_valcon = valcon_of_tycon dom in let j = pretype_type dom_valcon env evdref lvar c1 in let var = (name,None,j.utj_val) in let j' = pretype rng (push_rel var env) evdref lvar c2 in judge_of_abstraction env (orelse_name name name') j j' | RProd(loc,name,bk,c1,c2) -> let j = pretype_type empty_valcon env evdref lvar c1 in let var = (name,j.utj_val) in let env' = push_rel_assum var env in let j' = pretype_type empty_valcon env' evdref lvar c2 in let resj = try judge_of_product env name j j' with TypeError _ as e -> Stdpp.raise_with_loc loc e in inh_conv_coerce_to_tycon loc env evdref resj tycon | RLetIn(loc,name,c1,c2) -> let j = pretype empty_tycon env evdref lvar c1 in let t = refresh_universes j.uj_type in let var = (name,Some j.uj_val,t) in let tycon = lift_tycon 1 tycon in let j' = pretype tycon (push_rel var env) evdref lvar c2 in { uj_val = mkLetIn (name, j.uj_val, t, j'.uj_val) ; uj_type = subst1 j.uj_val j'.uj_type } | RLetTuple (loc,nal,(na,po),c,d) -> let cj = pretype empty_tycon env evdref lvar c in let (IndType (indf,realargs)) = try find_rectype env (evars_of !evdref) cj.uj_type with Not_found -> let cloc = loc_of_rawconstr c in error_case_not_inductive_loc cloc env (evars_of !evdref) cj in let cstrs = get_constructors env indf in if Array.length cstrs <> 1 then user_err_loc (loc,"",str "Destructing let is only for inductive types with one constructor."); let cs = cstrs.(0) in if List.length nal <> cs.cs_nargs then user_err_loc (loc,"", str "Destructing let on this type expects " ++ int cs.cs_nargs ++ str " variables."); let fsign = List.map2 (fun na (_,c,t) -> (na,c,t)) (List.rev nal) cs.cs_args in let env_f = push_rels fsign env in (* Make dependencies from arity signature impossible *) let arsgn = let arsgn,_ = get_arity env indf in if not !allow_anonymous_refs then List.map (fun (_,b,t) -> (Anonymous,b,t)) arsgn else arsgn in let psign = (na,None,build_dependent_inductive env indf)::arsgn in let nar = List.length arsgn in (match po with | Some p -> let env_p = push_rels psign env in let pj = pretype_type empty_valcon env_p evdref lvar p in let ccl = nf_isevar !evdref pj.utj_val in let psign = make_arity_signature env true indf in (* with names *) let p = it_mkLambda_or_LetIn ccl psign in let inst = (Array.to_list cs.cs_concl_realargs) @[build_dependent_constructor cs] in let lp = lift cs.cs_nargs p in let fty = hnf_lam_applist env (evars_of !evdref) lp inst in let fj = pretype (mk_tycon fty) env_f evdref lvar d in let f = it_mkLambda_or_LetIn fj.uj_val fsign in let v = let mis,_ = dest_ind_family indf in let ci = make_case_info env mis LetStyle in mkCase (ci, p, cj.uj_val,[|f|]) in { uj_val = v; uj_type = substl (realargs@[cj.uj_val]) ccl } | None -> let tycon = lift_tycon cs.cs_nargs tycon in let fj = pretype tycon env_f evdref lvar d in let f = it_mkLambda_or_LetIn fj.uj_val fsign in let ccl = nf_isevar !evdref fj.uj_type in let ccl = if noccur_between 1 cs.cs_nargs ccl then lift (- cs.cs_nargs) ccl else error_cant_find_case_type_loc loc env (evars_of !evdref) cj.uj_val in let ccl = refresh_universes ccl in let p = it_mkLambda_or_LetIn (lift (nar+1) ccl) psign in let v = let mis,_ = dest_ind_family indf in let ci = make_case_info env mis LetStyle in mkCase (ci, p, cj.uj_val,[|f|] ) in { uj_val = v; uj_type = ccl }) | RIf (loc,c,(na,po),b1,b2) -> let cj = pretype empty_tycon env evdref lvar c in let (IndType (indf,realargs)) = try find_rectype env (evars_of !evdref) cj.uj_type with Not_found -> let cloc = loc_of_rawconstr c in error_case_not_inductive_loc cloc env (evars_of !evdref) cj in let cstrs = get_constructors env indf in if Array.length cstrs <> 2 then user_err_loc (loc,"", str "If is only for inductive types with two constructors."); let arsgn = let arsgn,_ = get_arity env indf in if not !allow_anonymous_refs then (* Make dependencies from arity signature impossible *) List.map (fun (_,b,t) -> (Anonymous,b,t)) arsgn else arsgn in let nar = List.length arsgn in let psign = (na,None,build_dependent_inductive env indf)::arsgn in let pred,p = match po with | Some p -> let env_p = push_rels psign env in let pj = pretype_type empty_valcon env_p evdref lvar p in let ccl = nf_evar (evars_of !evdref) pj.utj_val in let pred = it_mkLambda_or_LetIn ccl psign in let typ = lift (- nar) (beta_applist (pred,[cj.uj_val])) in let jtyp = inh_conv_coerce_to_tycon loc env evdref {uj_val = pred; uj_type = typ} tycon in jtyp.uj_val, jtyp.uj_type | None -> let p = match tycon with | Some (None, ty) -> ty | None | Some _ -> e_new_evar evdref env ~src:(loc,InternalHole) (new_Type ()) in it_mkLambda_or_LetIn (lift (nar+1) p) psign, p in let pred = nf_evar (evars_of !evdref) pred in let p = nf_evar (evars_of !evdref) p in (* msgnl (str "Pred is: " ++ Termops.print_constr_env env pred);*) let f cs b = let n = rel_context_length cs.cs_args in let pi = lift n pred in (* liftn n 2 pred ? *) let pi = beta_applist (pi, [build_dependent_constructor cs]) in let csgn = if not !allow_anonymous_refs then List.map (fun (_,b,t) -> (Anonymous,b,t)) cs.cs_args else List.map (fun (n, b, t) -> match n with Name _ -> (n, b, t) | Anonymous -> (Name (id_of_string "H"), b, t)) cs.cs_args in let env_c = push_rels csgn env in (* msgnl (str "Pi is: " ++ Termops.print_constr_env env_c pi); *) let bj = pretype (mk_tycon pi) env_c evdref lvar b in it_mkLambda_or_LetIn bj.uj_val cs.cs_args in let b1 = f cstrs.(0) b1 in let b2 = f cstrs.(1) b2 in let v = let mis,_ = dest_ind_family indf in let ci = make_case_info env mis IfStyle in mkCase (ci, pred, cj.uj_val, [|b1;b2|]) in { uj_val = v; uj_type = p } | RCases (loc,sty,po,tml,eqns) -> Cases.compile_cases loc sty ((fun vtyc env evdref -> pretype vtyc env evdref lvar),evdref) tycon env (* loc *) (po,tml,eqns) | RCast (loc,c,k) -> let cj = match k with CastCoerce -> let cj = pretype empty_tycon env evdref lvar c in evd_comb1 (Coercion.inh_coerce_to_base loc env) evdref cj | CastConv (k,t) -> let tj = pretype_type empty_valcon env evdref lvar t in let cj = pretype (mk_tycon tj.utj_val) env evdref lvar c in (* User Casts are for helping pretyping, experimentally not to be kept*) (* ... except for Correctness *) let v = mkCast (cj.uj_val, k, tj.utj_val) in { uj_val = v; uj_type = tj.utj_val } in inh_conv_coerce_to_tycon loc env evdref cj tycon | RDynamic (loc,d) -> if (tag d) = "constr" then let c = constr_out d in let j = (Retyping.get_judgment_of env (evars_of !evdref) c) in j (*inh_conv_coerce_to_tycon loc env evdref j tycon*) else user_err_loc (loc,"pretype",(str "Not a constr tagged Dynamic.")) (* [pretype_type valcon env evdref lvar c] coerces [c] into a type *) and pretype_type valcon env evdref lvar = function | RHole loc -> (match valcon with | Some v -> let s = let sigma = evars_of !evdref in let t = Retyping.get_type_of env sigma v in match kind_of_term (whd_betadeltaiota env sigma t) with | Sort s -> s | Evar ev when is_Type (existential_type sigma ev) -> evd_comb1 (define_evar_as_sort) evdref ev | _ -> anomaly "Found a type constraint which is not a type" in { utj_val = v; utj_type = s } | None -> let s = new_Type_sort () in { utj_val = e_new_evar evdref env ~src:loc (mkSort s); utj_type = s}) | c -> let j = pretype empty_tycon env evdref lvar c in let loc = loc_of_rawconstr c in let tj = evd_comb1 (Coercion.inh_coerce_to_sort loc env) evdref j in match valcon with | None -> tj | Some v -> if e_cumul env evdref v tj.utj_val then tj else error_unexpected_type_loc (loc_of_rawconstr c) env (evars_of !evdref) tj.utj_val v let pretype_gen_aux evdref env lvar kind c = let c' = match kind with | OfType exptyp -> let tycon = match exptyp with None -> empty_tycon | Some t -> mk_tycon t in (pretype tycon env evdref lvar c).uj_val | IsType -> (pretype_type empty_valcon env evdref lvar c).utj_val in let evd,_ = consider_remaining_unif_problems env !evdref in evdref := evd; c' let pretype_gen evdref env lvar kind c = let c = pretype_gen_aux evdref env lvar kind c in evdref := Typeclasses.resolve_typeclasses ~onlyargs:true ~fail:false env !evdref; nf_evar (evars_of !evdref) c (* TODO: comment faire remonter l'information si le typage a resolu des variables du sigma original. il faudrait que la fonction de typage retourne aussi le nouveau sigma... *) let understand_judgment sigma env c = let evdref = ref (create_evar_defs sigma) in let j = pretype empty_tycon env evdref ([],[]) c in let evd,_ = consider_remaining_unif_problems env !evdref in let j = j_nf_evar (evars_of evd) j in let evd = Typeclasses.resolve_typeclasses ~onlyargs:true ~fail:true env evd in let j = j_nf_evar (evars_of evd) j in check_evars env sigma evd (mkCast(j.uj_val,DEFAULTcast, j.uj_type)); j let understand_judgment_tcc evdref env c = let j = pretype empty_tycon env evdref ([],[]) c in let sigma = evars_of !evdref in let j = j_nf_evar sigma j in j (* Raw calls to the unsafe inference machine: boolean says if we must fail on unresolved evars; the unsafe_judgment list allows us to extend env with some bindings *) let ise_pretype_gen fail_evar sigma env lvar kind c = let evdref = ref (Evd.create_evar_defs sigma) in let c = pretype_gen evdref env lvar kind c in let evd,_ = consider_remaining_unif_problems env !evdref in if fail_evar then let evd = Typeclasses.resolve_typeclasses ~onlyargs:false ~fail:true env evd in let c = Evarutil.nf_isevar evd c in check_evars env Evd.empty evd c; evd, c else evd, c (** Entry points of the high-level type synthesis algorithm *) let understand_gen kind sigma env c = snd (ise_pretype_gen true sigma env ([],[]) kind c) let understand sigma env ?expected_type:exptyp c = snd (ise_pretype_gen true sigma env ([],[]) (OfType exptyp) c) let understand_type sigma env c = snd (ise_pretype_gen true sigma env ([],[]) IsType c) let understand_ltac sigma env lvar kind c = ise_pretype_gen false sigma env lvar kind c let understand_tcc_evars evdref env kind c = pretype_gen evdref env ([],[]) kind c let understand_tcc ?(resolve_classes=true) sigma env ?expected_type:exptyp c = let evd, t = if resolve_classes then ise_pretype_gen false sigma env ([],[]) (OfType exptyp) c else let evdref = ref (Evd.create_evar_defs sigma) in let c = pretype_gen_aux evdref env ([],[]) (OfType exptyp) c in !evdref, nf_isevar !evdref c in Evd.evars_of evd, t end module Default : S = Pretyping_F(Coercion.Default)