path: root/compiler/Translate.ml

open Interpreter
open Types
open Values
open LlbcAst
open Contexts
open Errors
module SA = SymbolicAst
module Micro = PureMicroPasses
open TranslateCore

(** The local logger *)
let log = TranslateCore.log

(** The result of running the symbolic interpreter on a function:
    - the list of symbolic values used for the input values
    - the generated symbolic AST
*)
type symbolic_fun_translation = symbolic_value list * SA.expression

(** Execute the symbolic interpreter on a function to generate a list of symbolic ASTs,
    for the forward function and the backward functions.
*)
let translate_function_to_symbolics (trans_ctx : trans_ctx) (fdef : fun_decl) :
    symbolic_fun_translation option =
  (* Debug *)
  log#ldebug
    (lazy
      ("translate_function_to_symbolics: " ^ name_to_string trans_ctx fdef.name));

  match fdef.body with
  | None -> None
  | Some _ ->
      (* Evaluate *)
      let synthesize = true in
      let inputs, symb = evaluate_function_symbolic synthesize trans_ctx fdef in
      Some (inputs, Option.get symb)

(** Translate a function, by generating its forward and backward translations.

    [fun_sigs]: maps the forward/backward functions to their signatures. In case
    of backward functions, we also provide names for the outputs.
    TODO: maybe we should introduce a record for this.
*)
let translate_function_to_pure_aux (trans_ctx : trans_ctx)
    (pure_type_decls : Pure.type_decl Pure.TypeDeclId.Map.t)
    (fun_dsigs : Pure.decomposed_fun_sig FunDeclId.Map.t) (fdef : fun_decl) :
    pure_fun_translation_no_loops =
  (* Debug *)
  log#ldebug
    (lazy ("translate_function_to_pure: " ^ name_to_string trans_ctx fdef.name));

  (* Compute the symbolic ASTs, if the function is transparent *)
  let symbolic_trans = translate_function_to_symbolics trans_ctx fdef in

  (* Convert the symbolic ASTs to pure ASTs: *)

  (* Initialize the context *)
  let sv_to_var = SymbolicValueId.Map.empty in
  let var_counter = Pure.VarId.generator_zero in
  let state_var, var_counter = Pure.VarId.fresh var_counter in
  let fuel0, var_counter = Pure.VarId.fresh var_counter in
  let fuel, var_counter = Pure.VarId.fresh var_counter in
  let calls = FunCallId.Map.empty in
  let abstractions = AbstractionId.Map.empty in
  let recursive_type_decls =
    TypeDeclId.Set.of_list
      (List.filter_map
         (fun (tid, g) ->
           match g with
           | Charon.GAst.NonRecGroup _ -> None
           | RecGroup _ -> Some tid)
         (TypeDeclId.Map.bindings trans_ctx.type_ctx.type_decls_groups))
  in
  let type_ctx =
    {
      SymbolicToPure.type_infos = trans_ctx.type_ctx.type_infos;
      llbc_type_decls = trans_ctx.type_ctx.type_decls;
      type_decls = pure_type_decls;
      recursive_decls = recursive_type_decls;
    }
  in
  let fun_ctx =
    {
      SymbolicToPure.llbc_fun_decls = trans_ctx.fun_ctx.fun_decls;
      fun_infos = trans_ctx.fun_ctx.fun_infos;
      regions_hierarchies = trans_ctx.fun_ctx.regions_hierarchies;
    }
  in
  let global_ctx =
    { SymbolicToPure.llbc_global_decls = trans_ctx.global_ctx.global_decls }
  in

  (* Compute the set of loops, and find better ids for them (starting at 0).
     Note that we only need to explore the forward function: the backward
     functions should contain the same set of loops.
  *)
  let loop_ids_map =
    match symbolic_trans with
    | None -> LoopId.Map.empty
    | Some (_, ast) ->
        let m = ref LoopId.Map.empty in
        let _, fresh_loop_id = Pure.LoopId.fresh_stateful_generator () in

        let visitor =
          object
            inherit [_] SA.iter_expression as super

            method! visit_loop env loop =
              let _ =
                match LoopId.Map.find_opt loop.loop_id !m with
                | Some _ -> ()
                | None -> m := LoopId.Map.add loop.loop_id (fresh_loop_id ()) !m
              in
              super#visit_loop env loop
          end
        in
        visitor#visit_expression () ast;
        !m
  in

  let sg =
    SymbolicToPure.translate_fun_sig_from_decl_to_decomposed trans_ctx fdef
  in

  let var_counter, back_state_vars = (var_counter, []) in
  let back_state_vars = RegionGroupId.Map.of_list back_state_vars in

  let ctx =
    {
      span = fdef.item_meta.span;
      decls_ctx = trans_ctx;
      SymbolicToPure.bid = None;
      sg;
      fun_dsigs;
      (* Will need to be updated for the backward functions *)
      sv_to_var;
      var_counter = ref var_counter;
      state_var;
      back_state_vars;
      fuel0;
      fuel;
      type_ctx;
      fun_ctx;
      global_ctx;
      trait_decls_ctx = trans_ctx.trait_decls_ctx.trait_decls;
      trait_impls_ctx = trans_ctx.trait_impls_ctx.trait_impls;
      fun_decl = fdef;
      forward_inputs = [];
      (* Initialized just below *)
      backward_inputs_no_state = RegionGroupId.Map.empty;
      (* Initialized just below *)
      backward_inputs_with_state = RegionGroupId.Map.empty;
      backward_outputs = None;
      (* Empty for now *)
      calls;
      abstractions;
      loop_id = None;
      inside_loop = false;
      loop_ids_map;
      loops = Pure.LoopId.Map.empty;
      mk_return = None;
      mk_panic = None;
    }
  in

  (* Add the forward inputs (the initialized input variables for the forward
     function)
  *)
  let ctx =
    match (fdef.body, symbolic_trans) with
    | None, None -> ctx
    | Some body, Some (input_svs, _) ->
        let forward_input_vars = LlbcAstUtils.fun_body_get_input_vars body in
        let forward_input_varnames =
          List.map (fun (v : var) -> v.name) forward_input_vars
        in
        let input_svs = List.combine forward_input_varnames input_svs in
        let ctx, forward_inputs =
          SymbolicToPure.fresh_named_vars_for_symbolic_values input_svs ctx
        in
        { ctx with forward_inputs }
    | _ -> craise __FILE__ __LINE__ fdef.item_meta.span "Unreachable"
  in

  (* Add the backward inputs *)
  let backward_inputs_no_state, backward_inputs_with_state = ([], []) in
  let backward_inputs_no_state =
    RegionGroupId.Map.of_list backward_inputs_no_state
  in
  let backward_inputs_with_state =
    RegionGroupId.Map.of_list backward_inputs_with_state
  in
  let ctx = { ctx with backward_inputs_no_state; backward_inputs_with_state } in

  (* Translate the function *)
  match symbolic_trans with
  | None -> SymbolicToPure.translate_fun_decl ctx None
  | Some (_, ast) -> SymbolicToPure.translate_fun_decl ctx (Some ast)

let translate_function_to_pure (trans_ctx : trans_ctx)
    (pure_type_decls : Pure.type_decl Pure.TypeDeclId.Map.t)
    (fun_dsigs : Pure.decomposed_fun_sig FunDeclId.Map.t) (fdef : fun_decl) :
    pure_fun_translation_no_loops option =
  try
    Some
      (translate_function_to_pure_aux trans_ctx pure_type_decls fun_dsigs fdef)
  with CFailure (span, _) ->
    let name = name_to_string trans_ctx fdef.name in
    let name_pattern = name_to_pattern_string trans_ctx fdef.name in
    save_error __FILE__ __LINE__ span
      ("Could not translate the function '" ^ name
     ^ " because of previous error\nName pattern: '" ^ name_pattern ^ "'");
    None

(* TODO: factor out the return type *)
let translate_crate_to_pure (crate : crate) :
    trans_ctx
    * Pure.type_decl list
    * pure_fun_translation list
    * Pure.trait_decl list
    * Pure.trait_impl list =
  (* Debug *)
  log#ldebug (lazy "translate_crate_to_pure");

  (* Compute the translation context *)
  let trans_ctx = compute_contexts crate in

  (* Translate all the type definitions *)
  let type_decls = SymbolicToPure.translate_type_decls trans_ctx in

  (* Compute the type definition map *)
  let type_decls_map =
    Pure.TypeDeclId.Map.of_list
      (List.map (fun (def : Pure.type_decl) -> (def.def_id, def)) type_decls)
  in

  (* Compute the decomposed fun sigs for the whole crate *)
  let fun_dsigs =
    FunDeclId.Map.of_list
      (List.filter_map
         (fun (fdef : LlbcAst.fun_decl) ->
           try
             Some
               ( fdef.def_id,
                 SymbolicToPure.translate_fun_sig_from_decl_to_decomposed
                   trans_ctx fdef )
           with CFailure (span, _) ->
             let name = name_to_string trans_ctx fdef.name in
             let name_pattern = name_to_pattern_string trans_ctx fdef.name in
             save_error __FILE__ __LINE__ span
               ("Could not translate the function signature of '" ^ name
              ^ " because of previous error\nName pattern: '" ^ name_pattern
              ^ "'");
             None)
         (FunDeclId.Map.values crate.fun_decls))
  in

  (* Translate all the *transparent* functions *)
  let pure_translations =
    List.filter_map
      (translate_function_to_pure trans_ctx type_decls_map fun_dsigs)
      (FunDeclId.Map.values crate.fun_decls)
  in

  (* Translate the trait declarations *)
  let trait_decls =
    List.filter_map
      (fun d ->
        try Some (SymbolicToPure.translate_trait_decl trans_ctx d)
        with CFailure (span, _) ->
          let name = name_to_string trans_ctx d.name in
          let name_pattern = name_to_pattern_string trans_ctx d.name in
          save_error __FILE__ __LINE__ span
            ("Could not translate the trait declaration '" ^ name
           ^ " because of previous error\nName pattern: '" ^ name_pattern ^ "'"
            );
          None)
      (TraitDeclId.Map.values trans_ctx.trait_decls_ctx.trait_decls)
  in

  (* Translate the trait implementations *)
  let trait_impls =
    List.filter_map
      (fun d ->
        try Some (SymbolicToPure.translate_trait_impl trans_ctx d)
        with CFailure (span, _) ->
          let name = name_to_string trans_ctx d.name in
          let name_pattern = name_to_pattern_string trans_ctx d.name in
          save_error __FILE__ __LINE__ span
            ("Could not translate the trait instance '" ^ name
           ^ " because of previous error\nName pattern: '" ^ name_pattern ^ "'"
            );
          None)
      (TraitImplId.Map.values trans_ctx.trait_impls_ctx.trait_impls)
  in

  (* Apply the micro-passes *)
  let pure_translations =
    Micro.apply_passes_to_pure_fun_translations trans_ctx pure_translations
  in

  (* Return *)
  (trans_ctx, type_decls, pure_translations, trait_decls, trait_impls)

type gen_ctx = ExtractBase.extraction_ctx

type gen_config = {
  extract_types : bool;
  extract_decreases_clauses : bool;
  extract_template_decreases_clauses : bool;
  extract_fun_decls : bool;
  extract_trait_decls : bool;
  extract_trait_impls : bool;
  extract_transparent : bool;
      (** If [true], extract the transparent declarations, otherwise ignore. *)
  extract_opaque : bool;
      (** If [true], extract the opaque declarations, otherwise ignore.

          For now, this controls only the opaque *functions*, not the opaque
          globals or types.
          TODO: update this. This is not trivial if we want to extract the opaque
          types in an opaque module, because some non-opaque types may refer
          to opaque types and vice-versa.
       *)
  extract_state_type : bool;
      (** If [true], generate a definition/declaration for the state type *)
  extract_globals : bool;
      (** If [true], generate a definition/declaration for top-level (global)
          declarations *)
  interface : bool;
      (** [true] if we generate an interface file, [false] otherwise.
          For now, this only impacts whether we use [val] or [assume val] for the
          opaque definitions. In the future, we might want to extract all the
          declarations in an interface file, together with an implementation file
          if needed.
       *)
  test_trans_unit_functions : bool;
}

(** Returns the pair: (has opaque type decls, has opaque fun decls).

    [filter_assumed]: if [true], do not consider as opaque the external definitions
    that we will map to definitions from the standard library.
 *)
let crate_has_opaque_non_builtin_decls (ctx : gen_ctx) (filter_assumed : bool) :
    bool * bool =
  let types, funs =
    LlbcAstUtils.crate_get_opaque_non_builtin_decls ctx.crate filter_assumed
  in
  log#ldebug
    (lazy
      ("Opaque decls:" ^ "\n- types:\n"
      ^ String.concat ",\n" (List.map show_type_decl types)
      ^ "\n- functions:\n"
      ^ String.concat ",\n" (List.map show_fun_decl funs)));
  (types <> [], funs <> [])

(** Export a type declaration.

    It may happen that we have to extract extra information/instructions.
    For instance, we might need to define some projector notations. This is
    why we have the two booleans [extract_decl] and [extract_extra_info].
    If [extract_decl] is [true], then we extract the type declaration. If
    [extract_extra_info] is [true], we extract this extra information (after
    the declaration, if both booleans are [true]).
 *)
let export_type (fmt : Format.formatter) (config : gen_config) (ctx : gen_ctx)
    (type_decl_group : Pure.TypeDeclId.Set.t) (kind : ExtractBase.decl_kind)
    (def : Pure.type_decl) (extract_decl : bool) (extract_extra_info : bool) :
    unit =
  (* Update the kind, if the type is opaque *)
  let is_opaque, kind =
    match def.kind with
    | Enum _ | Struct _ -> (false, kind)
    | Opaque ->
        let kind =
          if config.interface then ExtractBase.Declared else ExtractBase.Assumed
        in
        (true, kind)
  in
  (* Extract, if the config instructs to do so (depending on whether the type
     is opaque or not). Remark: we don't check if the definitions are builtin
     here but in the function [export_types_group]: the reason is that if one
     definition in the group is builtin, then we must check that all the
     definitions are marked builtin *)
  let extract =
    (is_opaque && config.extract_opaque)
    || ((not is_opaque) && config.extract_transparent)
  in
  if extract then (
    if extract_decl then
      Extract.extract_type_decl ctx fmt type_decl_group kind def;
    if extract_extra_info then
      Extract.extract_type_decl_extra_info ctx fmt kind def)

(** Export a group of types.

    [is_rec]: [true] if the types are recursive. Necessarily [true] if there is
    > 1 type to extract.
 *)
let export_types_group (fmt : Format.formatter) (config : gen_config)
    (ctx : gen_ctx) (is_rec : bool) (ids : Pure.TypeDeclId.id list) : unit =
  assert (ids <> []);
  let export_type = export_type fmt config ctx in
  let ids_set = Pure.TypeDeclId.Set.of_list ids in
  let export_type_decl kind id = export_type ids_set kind id true false in
  let export_type_extra_info kind id = export_type ids_set kind id false true in

  (* Rem.: we shouldn't have (mutually) recursive opaque types *)
  let num_decls = List.length ids in
  let is_mut_rec = num_decls > 1 in
  let kind_from_index i =
    if not is_mut_rec then
      if is_rec then ExtractBase.SingleRec else ExtractBase.SingleNonRec
    else if i = 0 then ExtractBase.MutRecFirst
    else if i = num_decls - 1 then ExtractBase.MutRecLast
    else ExtractBase.MutRecInner
  in

  (* Retrieve the declarations - note that some of them might have been ignored in
     case of errors *)
  let defs =
    List.filter_map
      (fun id -> Pure.TypeDeclId.Map.find_opt id ctx.trans_types)
      ids
  in

  (* Check if the definition are builtin - if yes they must be ignored.
     Note that if one definition in the group is builtin, then all the
     definitions must be builtin *)
  let builtin =
    let open ExtractBuiltin in
    let types_map = builtin_types_map () in
    List.map
      (fun (def : Pure.type_decl) ->
        match_name_find_opt ctx.trans_ctx def.llbc_name types_map <> None)
      defs
  in

  let dont_extract (d : Pure.type_decl) : bool =
    match d.kind with
    | Enum _ | Struct _ -> not config.extract_transparent
    | Opaque -> not config.extract_opaque
  in

  if List.exists (fun b -> b) builtin then
    (* Sanity check *)
    assert (List.for_all (fun b -> b) builtin)
  else if List.exists dont_extract defs then
    (* Check if we have to ignore declarations *)
    (* Sanity check *)
    assert (List.for_all dont_extract defs)
  else (
    (* Extract the type declarations.

       Because some declaration groups are delimited, we wrap the declarations
       between [{start,end}_type_decl_group].

       Ex.:
       ====
       When targeting HOL4, the calls to [{start,end}_type_decl_group] would generate
       the [Datatype] and [End] delimiters in the snippet of code below:

       {[
         Datatype:
           tree =
             TLeaf 'a
           | TNode node ;

           node =
             Node (tree list)
         End
       ]}
    *)
    Extract.start_type_decl_group ctx fmt is_rec defs;
    List.iteri
      (fun i def ->
        let kind = kind_from_index i in
        export_type_decl kind def)
      defs;
    Extract.end_type_decl_group fmt is_rec defs;

    (* Export the extra information (ex.: [Arguments] instructions in Coq) *)
    List.iteri
      (fun i def ->
        let kind = kind_from_index i in
        export_type_extra_info kind def)
      defs)

(** Export a global declaration.

    TODO: check correct behavior with opaque globals.
 *)
let export_global (fmt : Format.formatter) (config : gen_config) (ctx : gen_ctx)
    (id : GlobalDeclId.id) : unit =
  let global_decls = ctx.trans_ctx.global_ctx.global_decls in
  let global = GlobalDeclId.Map.find id global_decls in
  let trans = FunDeclId.Map.find global.body ctx.trans_funs in
  sanity_check __FILE__ __LINE__ (trans.loops = []) global.item_meta.span;
  let body = trans.f in

  let is_opaque = Option.is_none body.Pure.body in
  (* Check if we extract the global *)
  let extract =
    config.extract_globals
    && (((not is_opaque) && config.extract_transparent)
       || (is_opaque && config.extract_opaque))
  in
  (* Check if it is a builtin global - if yes, we ignore it because we
     map the definition to one in the standard library *)
  let open ExtractBuiltin in
  let extract =
    extract
    && match_name_find_opt ctx.trans_ctx global.name builtin_globals_map = None
  in
  if extract then
    (* We don't wrap global declaration groups between calls to functions
       [{start, end}_global_decl_group] (which don't exist): global declaration
       groups are always singletons, so the [extract_global_decl] function
       takes care of generating the delimiters.
    *)
    let global =
      try Some (SymbolicToPure.translate_global ctx.trans_ctx global)
      with CFailure (span, _) ->
        let name = name_to_string ctx.trans_ctx global.name in
        let name_pattern = name_to_pattern_string ctx.trans_ctx global.name in
        save_error __FILE__ __LINE__ span
          ("Could not translate the global declaration '" ^ name
         ^ " because of previous error\nName pattern: '" ^ name_pattern ^ "'");
        None
    in
    Extract.extract_global_decl ctx fmt global body config.interface

(** Utility.

    Export a group of functions, used by {!export_functions_group}.

    We need this because for every function in Rust we may generate several functions
    in the translation (a forward function, several backward functions, loop
    functions, etc.). Those functions might call each other in different
    ways. In particular, they may be mutually recursive, in which case we might
    be able to group them into several groups of mutually recursive definitions,
    etc. For this reason, {!export_functions_group} computes the dependency
    graph of the functions as well as their strongly connected components, and
    gives each SCC at a time to {!export_functions_group_scc}.

    Rem.: this function only extracts the function *declarations*. It doesn't
    extract the decrease clauses, nor does it extract the unit tests.

    Rem.: this function doesn't check [config.extract_fun_decls]: it should have
    been checked by the caller.
 *)
let export_functions_group_scc (fmt : Format.formatter) (config : gen_config)
    (ctx : gen_ctx) (is_rec : bool) (decls : Pure.fun_decl list) : unit =
  (* Utility to check a function has a decrease clause *)
  let has_decreases_clause (def : Pure.fun_decl) : bool =
    PureUtils.FunLoopIdSet.mem (def.def_id, def.loop_id)
      ctx.functions_with_decreases_clause
  in

  (* Extract the function declarations *)
  (* Check if the functions are mutually recursive *)
  let is_mut_rec = List.length decls > 1 in
  assert ((not is_mut_rec) || is_rec);
  let decls_length = List.length decls in
  (* We open and close the declaration group with [{start, end}_fun_decl_group].

     Some backends require the groups to be delimited. For instance, if we target
     HOL4, the calls to [{start, end}_fun_decl_group] would generate the
     [val ... = Define `] and [`] delimiters in the snippet of code below:

     {[
       val ... = Define `
         (even (i : num) : bool result = if i = 0 then Return T else odd (i - 1)) /\
         (odd (i : num) : bool result = if i = 0 then Return F else even (i - 1))
       `
     ]}

     TODO: in practice splitting the code this way doesn't work so well: merge
     the start/end decl group functions with the extract_fun_decl function?
  *)
  (* Filter the definitions - we generate a list of continuations *)
  let extract_defs =
    List.mapi
      (fun i def ->
        let is_opaque = Option.is_none def.Pure.body in
        let kind =
          if is_opaque then
            if config.interface then ExtractBase.Declared
            else ExtractBase.Assumed
          else if not is_rec then ExtractBase.SingleNonRec
          else if is_mut_rec then
            (* If the functions are mutually recursive, we need to distinguish:
             * - the first of the group
             * - the last of the group
             * - the inner functions
             *)
            if i = 0 then ExtractBase.MutRecFirst
            else if i = decls_length - 1 then ExtractBase.MutRecLast
            else ExtractBase.MutRecInner
          else ExtractBase.SingleRec
        in
        let has_decr_clause =
          has_decreases_clause def && config.extract_decreases_clauses
        in
        (* Check if the definition needs to be filtered or not *)
        if
          ((not is_opaque) && config.extract_transparent)
          || (is_opaque && config.extract_opaque)
        then
          Some
            (fun () ->
              Extract.extract_fun_decl ctx fmt kind has_decr_clause def)
        else None)
      decls
  in
  let extract_defs = List.filter_map (fun x -> x) extract_defs in
  if extract_defs <> [] then (
    Extract.start_fun_decl_group ctx fmt is_rec decls;
    List.iter (fun f -> f ()) extract_defs;
    Extract.end_fun_decl_group fmt is_rec decls)

(** Export a group of function declarations.

    In case of (non-mutually) recursive functions, we use a simple procedure to
    check if the forward and backward functions are mutually recursive.
 *)
let export_functions_group (fmt : Format.formatter) (config : gen_config)
    (ctx : gen_ctx) (pure_ls : pure_fun_translation list) : unit =
  (* Check if the definition are builtin - if yes they must be ignored.
     Note that if one definition in the group is builtin, then all the
     definitions must be builtin *)
  let builtin =
    let open ExtractBuiltin in
    let funs_map = builtin_funs_map () in
    List.map
      (fun (trans : pure_fun_translation) ->
        match_name_find_opt ctx.trans_ctx trans.f.llbc_name funs_map <> None)
      pure_ls
  in

  if List.exists (fun b -> b) builtin then
    (* Sanity check *)
    assert (List.for_all (fun b -> b) builtin)
  else
    (* Utility to check a function has a decrease clause *)
    let has_decreases_clause (def : Pure.fun_decl) : bool =
      PureUtils.FunLoopIdSet.mem (def.def_id, def.loop_id)
        ctx.functions_with_decreases_clause
    in

    (* Extract the decrease clauses template bodies *)
    if config.extract_template_decreases_clauses then
      List.iter
        (fun f ->
          (* We only generate decreases clauses for the forward functions, because
             the termination argument should only depend on the forward inputs.
             The backward functions thus use the same decreases clauses as the
             forward function.

             Rem.: we might filter backward functions in {!PureMicroPasses}, but
             we don't remove forward functions. Instead, we remember if we should
             filter those functions at extraction time with a boolean (see the
             type of the [pure_ls] input parameter).
          *)
          let extract_decrease decl =
            let has_decr_clause = has_decreases_clause decl in
            if has_decr_clause then
              match Config.backend () with
              | Lean ->
                  Extract.extract_template_lean_termination_and_decreasing ctx
                    fmt decl
              | FStar ->
                  Extract.extract_template_fstar_decreases_clause ctx fmt decl
              | Coq ->
                  raise
                    (Failure "Coq doesn't have decreases/termination clauses")
              | HOL4 ->
                  raise
                    (Failure "HOL4 doesn't have decreases/termination clauses")
          in
          extract_decrease f.f;
          List.iter extract_decrease f.loops)
        pure_ls;

    (* Flatten the translated functions (concatenate the functions with
       the declarations introduced for the loops) *)
    let decls =
      List.concat (List.map (fun f -> List.append f.loops [ f.f ]) pure_ls)
    in

    (* Extract the function definitions *)
    (if config.extract_fun_decls then
       (* Group the mutually recursive definitions *)
       let subgroups = ReorderDecls.group_reorder_fun_decls decls in

       (* Extract the subgroups *)
       let export_subgroup (is_rec : bool) (decls : Pure.fun_decl list) : unit =
         export_functions_group_scc fmt config ctx is_rec decls
       in
       List.iter (fun (is_rec, decls) -> export_subgroup is_rec decls) subgroups);

    (* Insert unit tests if necessary *)
    if config.test_trans_unit_functions then
      List.iter
        (fun trans -> Extract.extract_unit_test_if_unit_fun ctx fmt trans.f)
        pure_ls

(** Export a trait declaration. *)
let export_trait_decl (fmt : Format.formatter) (_config : gen_config)
    (ctx : gen_ctx) (trait_decl_id : Pure.trait_decl_id) (extract_decl : bool)
    (extract_extra_info : bool) : unit =
  let trait_decl = TraitDeclId.Map.find trait_decl_id ctx.trans_trait_decls in
  (* Check if the trait declaration is builtin, in which case we ignore it *)
  let open ExtractBuiltin in
  if
    match_name_find_opt ctx.trans_ctx trait_decl.llbc_name
      (builtin_trait_decls_map ())
    = None
  then (
    let ctx = { ctx with trait_decl_id = Some trait_decl.def_id } in
    if extract_decl then Extract.extract_trait_decl ctx fmt trait_decl;
    if extract_extra_info then
      Extract.extract_trait_decl_extra_info ctx fmt trait_decl)
  else ()

(** Export a trait implementation. *)
let export_trait_impl (fmt : Format.formatter) (_config : gen_config)
    (ctx : gen_ctx) (trait_impl_id : Pure.trait_impl_id) : unit =
  (* Lookup the definition *)
  let trait_impl = TraitImplId.Map.find trait_impl_id ctx.trans_trait_impls in
  let trait_decl =
    Pure.TraitDeclId.Map.find trait_impl.impl_trait.trait_decl_id
      ctx.trans_trait_decls
  in
  (* Check if the trait implementation is builtin *)
  let builtin_info =
    let open ExtractBuiltin in
    let trait_impl =
      TraitImplId.Map.find trait_impl.def_id ctx.crate.trait_impls
    in
    match_name_with_generics_find_opt ctx.trans_ctx trait_decl.llbc_name
      trait_impl.impl_trait.decl_generics
      (builtin_trait_impls_map ())
  in
  match builtin_info with
  | None -> Extract.extract_trait_impl ctx fmt trait_impl
  | Some _ -> ()

(** A generic utility to generate the extracted definitions: as we may want to
    split the definitions between different files (or not), we can control
    what is precisely extracted.
 *)
let extract_definitions (fmt : Format.formatter) (config : gen_config)
    (ctx : gen_ctx) : unit =
  (* Export the definition groups to the file, in the proper order.
     - [extract_decl]: extract the type declaration (if not filtered)
     - [extract_extra_info]: extra the extra type information (e.g.,
       the [Arguments] information in Coq).
  *)
  let export_functions_group = export_functions_group fmt config ctx in
  let export_global = export_global fmt config ctx in
  let export_types_group = export_types_group fmt config ctx in
  let export_trait_decl_group id =
    export_trait_decl fmt config ctx id true false
  in
  let export_trait_decl_group_extra_info id =
    export_trait_decl fmt config ctx id false true
  in
  let export_trait_impl = export_trait_impl fmt config ctx in

  let export_state_type () : unit =
    let kind =
      if config.interface then ExtractBase.Declared else ExtractBase.Assumed
    in
    Extract.extract_state_type fmt ctx kind
  in

  let export_decl_group (dg : declaration_group) : unit =
    match dg with
    | TypeGroup (NonRecGroup id) ->
        if config.extract_types then export_types_group false [ id ]
    | TypeGroup (RecGroup ids) ->
        if config.extract_types then export_types_group true ids
    | FunGroup (NonRecGroup id) -> (
        (* Lookup - the translated function may not be in the map if we had
           to ignore it because of errors *)
        let pure_fun = FunDeclId.Map.find_opt id ctx.trans_funs in
        (* Special case: we skip trait method *declarations* (we will
           extract their type directly in the records we generate for
           the trait declarations themselves, there is no point in having
           separate type definitions) *)
        match pure_fun with
        | Some pure_fun -> (
            match pure_fun.f.Pure.kind with
            | TraitItemDecl _ -> ()
            | _ ->
                (* Translate *)
                export_functions_group [ pure_fun ])
        | None -> ())
    | FunGroup (RecGroup ids) ->
        (* General case of mutually recursive functions *)
        (* Lookup *)
        let pure_funs =
          List.filter_map
            (fun id -> FunDeclId.Map.find_opt id ctx.trans_funs)
            ids
        in
        (* Translate *)
        export_functions_group pure_funs
    | GlobalGroup id -> export_global id
    | TraitDeclGroup (RecGroup _ids) ->
        craise_opt_span __FILE__ __LINE__ None
          "Mutually recursive trait declarations are not supported"
    | TraitDeclGroup (NonRecGroup id) ->
        (* TODO: update to extract groups *)
        if config.extract_trait_decls && config.extract_transparent then (
          export_trait_decl_group id;
          export_trait_decl_group_extra_info id)
    | TraitImplGroup id ->
        if config.extract_trait_impls && config.extract_transparent then
          export_trait_impl id
  in

  (* If we need to export the state type: we try to export it after we defined
   * the type definitions, because if the user wants to define a model for the
   * type, they might want to reuse those in the state type.
   * More specifically: if we extract functions in the same file as the type,
   * we have no choice but to define the state type before the functions,
   * because they may reuse this state type: in this case, we define/declare
   * it at the very beginning. Otherwise, we define/declare it at the very end.
   *)
  if config.extract_state_type && config.extract_fun_decls then
    export_state_type ();

  List.iter export_decl_group ctx.crate.declarations;

  if config.extract_state_type && not config.extract_fun_decls then
    export_state_type ()

type extract_file_info = {
  filename : string;
  namespace : string;
  in_namespace : bool;
  open_namespace : bool;
  crate_name : string;
  rust_module_name : string;
  module_name : string;
  custom_msg : string;
  custom_imports : string list;
  custom_includes : string list;
}

let extract_file (config : gen_config) (ctx : gen_ctx) (fi : extract_file_info)
    : unit =
  (* Open the file and create the formatter *)
  let out = open_out fi.filename in
  let fmt = Format.formatter_of_out_channel out in

  (* Print the headers.
   * Note that we don't use the OCaml formatter for purpose: we want to control
   * line insertion (we have to make sure that some instructions like [open MODULE]
   * are printed on one line!).
   * This is ok as long as we end up with a line break, so that the formatter's
   * internal count is consistent with the state of the file.
   *)
  (* Create the header *)
  (match Config.backend () with
  | Lean ->
      Printf.fprintf out "-- THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS\n";
      Printf.fprintf out "-- [%s]%s\n" fi.rust_module_name fi.custom_msg
  | Coq | FStar | HOL4 ->
      Printf.fprintf out
        "(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)\n";
      Printf.fprintf out "(** [%s]%s *)\n" fi.rust_module_name fi.custom_msg);
  (* Generate the imports *)
  (match Config.backend () with
  | FStar ->
      Printf.fprintf out "module %s\n" fi.module_name;
      Printf.fprintf out "open Primitives\n";
      (* Add the custom imports *)
      List.iter (fun m -> Printf.fprintf out "open %s\n" m) fi.custom_imports;
      (* Add the custom includes *)
      List.iter
        (fun m -> Printf.fprintf out "include %s\n" m)
        fi.custom_includes;
      (* Z3 options - note that we use fuel 1 because it its useful for the decrease clauses *)
      Printf.fprintf out "\n#set-options \"--z3rlimit 50 --fuel 1 --ifuel 1\"\n"
  | Coq ->
      Printf.fprintf out "Require Import Primitives.\n";
      Printf.fprintf out "Import Primitives.\n";
      Printf.fprintf out "Require Import Coq.ZArith.ZArith.\n";
      Printf.fprintf out "Require Import List.\n";
      Printf.fprintf out "Import ListNotations.\n";
      Printf.fprintf out "Local Open Scope Primitives_scope.\n";

      (* Add the custom imports *)
      List.iter
        (fun m -> Printf.fprintf out "Require Import %s.\n" m)
        fi.custom_imports;
      (* Add the custom includes *)
      List.iter
        (fun m ->
          (* TODO: I don't really understand how the "Require Export",
             "Require Import", "Include" work.
             I used to have:
             {[
               Require Export %s.
               Import %s.
             ]}

             I now have:
             {[
               Require Import %s.
               Include %s.
             ]}
          *)
          Printf.fprintf out "Require Import %s.\n" m;
          Printf.fprintf out "Include %s.\n" m)
        fi.custom_includes;
      Printf.fprintf out "Module %s.\n" fi.module_name
  | Lean ->
      Printf.fprintf out "import Base\n";
      (* Add the custom imports *)
      List.iter (fun m -> Printf.fprintf out "import %s\n" m) fi.custom_imports;
      (* Add the custom includes *)
      List.iter (fun m -> Printf.fprintf out "import %s\n" m) fi.custom_includes;
      (* Always open the Primitives namespace *)
      Printf.fprintf out "open Primitives\n";
      (* It happens that we generate duplicated namespaces, like `betree.betree`.
         We deactivate the linter for this, because otherwise it leads to too much
         noise. *)
      Printf.fprintf out "set_option linter.dupNamespace false\n";
      (* The mathlib linter generates warnings when we use hash commands like `#assert`:
         we deactivate this linter. *)
      Printf.fprintf out "set_option linter.hashCommand false\n";
      (* Definitions often contain unused variables: deactivate the corresponding linter *)
      Printf.fprintf out "set_option linter.unusedVariables false\n";
      (* If we are inside the namespace: declare it *)
      if fi.in_namespace then Printf.fprintf out "\nnamespace %s\n" fi.namespace;
      (* We might need to open the namespace *)
      if fi.open_namespace then Printf.fprintf out "open %s\n" fi.namespace
  | HOL4 ->
      Printf.fprintf out "open primitivesLib divDefLib\n";
      (* Add the custom imports and includes *)
      let imports = fi.custom_imports @ fi.custom_includes in
      (* The imports are a list of module names: we need to add a "Theory" suffix *)
      let imports = List.map (fun s -> s ^ "Theory") imports in
      if imports <> [] then
        let imports = String.concat " " imports in
        Printf.fprintf out "open %s\n\n" imports
      else Printf.fprintf out "\n";
      (* Initialize the theory *)
      Printf.fprintf out "val _ = new_theory \"%s\"\n\n" fi.module_name);
  (* From now onwards, we use the formatter *)
  (* Set the margin *)
  Format.pp_set_margin fmt 80;

  (* Create a vertical box *)
  Format.pp_open_vbox fmt 0;

  (* Extract the definitions *)
  extract_definitions fmt config ctx;

  (* Close the box and end the formatting *)
  Format.pp_close_box fmt ();
  Format.pp_print_newline fmt ();

  (* Close the module *)
  (match Config.backend () with
  | FStar -> ()
  | Lean -> if fi.in_namespace then Printf.fprintf out "end %s\n" fi.namespace
  | HOL4 -> Printf.fprintf out "val _ = export_theory ()\n"
  | Coq -> Printf.fprintf out "End %s.\n" fi.module_name);

  (* Some logging *)
  if !Errors.error_list <> [] then
    log#linfo
      (lazy ("Generated the partial file (because of errors): " ^ fi.filename))
  else log#linfo (lazy ("Generated: " ^ fi.filename));

  (* Flush and close the file *)
  close_out out

(** Translate a crate and write the synthesized code to an output file. *)
let translate_crate (filename : string) (dest_dir : string) (crate : crate) :
    unit =
  (* Translate the module to the pure AST *)
  let trans_ctx, trans_types, trans_funs, trans_trait_decls, trans_trait_impls =
    translate_crate_to_pure crate
  in

  (* Initialize the names map by registering the keywords used in the
     language, as well as some primitive names ("u32", etc.).
     We insert the names of the local declarations later. *)
  let names_maps = Extract.initialize_names_maps () in

  (* We need to compute which functions are recursive, in order to know
   * whether we should generate a decrease clause or not. *)
  let rec_functions =
    List.map
      (fun trans ->
        let f =
          if trans.f.Pure.signature.fwd_info.effect_info.is_rec then
            [ (trans.f.def_id, None) ]
          else []
        in
        let loops =
          List.map
            (fun (def : Pure.fun_decl) -> [ (def.def_id, def.loop_id) ])
            trans.loops
        in
        f :: loops)
      trans_funs
  in
  let rec_functions : PureUtils.fun_loop_id list =
    List.concat (List.concat rec_functions)
  in
  let rec_functions = PureUtils.FunLoopIdSet.of_list rec_functions in

  (* Put the translated definitions in maps *)
  let trans_types =
    Pure.TypeDeclId.Map.of_list
      (List.map (fun (d : Pure.type_decl) -> (d.def_id, d)) trans_types)
  in
  let trans_funs : pure_fun_translation FunDeclId.Map.t =
    FunDeclId.Map.of_list
      (List.map
         (fun (trans : pure_fun_translation) -> (trans.f.def_id, trans))
         trans_funs)
  in

  (* Put everything in the context *)
  let ctx =
    let trans_trait_decls =
      TraitDeclId.Map.of_list
        (List.map
           (fun (d : Pure.trait_decl) -> (d.def_id, d))
           trans_trait_decls)
    in
    let trans_trait_impls =
      TraitImplId.Map.of_list
        (List.map
           (fun (d : Pure.trait_impl) -> (d.def_id, d))
           trans_trait_impls)
    in
    {
      ExtractBase.crate;
      trans_ctx;
      names_maps;
      indent_incr = 2;
      use_dep_ite =
        Config.backend () = Lean && !Config.extract_decreases_clauses;
      trait_decl_id = None (* None by default *);
      is_provided_method = false (* false by default *);
      trans_trait_decls;
      trans_trait_impls;
      trans_types;
      trans_funs;
      functions_with_decreases_clause = rec_functions;
      types_filter_type_args_map = Pure.TypeDeclId.Map.empty;
      funs_filter_type_args_map = Pure.FunDeclId.Map.empty;
      trait_impls_filter_type_args_map = Pure.TraitImplId.Map.empty;
    }
  in

  (* Register unique names for all the top-level types, globals, functions...
   * Note that the order in which we generate the names doesn't matter:
   * we just need to generate a mapping from identifier to name, and make
   * sure there are no name clashes. *)
  let ctx =
    List.fold_left
      (fun ctx def -> Extract.extract_type_decl_register_names ctx def)
      ctx
      (Pure.TypeDeclId.Map.values trans_types)
  in

  let ctx =
    List.fold_left
      (fun ctx (trans : pure_fun_translation) ->
        (* If requested by the user, register termination measures and decreases
           proofs for all the recursive functions *)
        let gen_decr_clause (def : Pure.fun_decl) =
          !Config.extract_decreases_clauses
          && PureUtils.FunLoopIdSet.mem
               (def.Pure.def_id, def.Pure.loop_id)
               rec_functions
        in
        (* Register the names, only if the function is not a global body -
         * those are handled later *)
        let is_global = trans.f.Pure.is_global_decl_body in
        if is_global then ctx
        else Extract.extract_fun_decl_register_names ctx gen_decr_clause trans)
      ctx
      (FunDeclId.Map.values trans_funs)
  in

  let ctx =
    List.fold_left Extract.extract_global_decl_register_names ctx
      (GlobalDeclId.Map.values crate.global_decls)
  in

  let ctx =
    List.fold_left Extract.extract_trait_decl_register_names ctx
      trans_trait_decls
  in

  let ctx =
    List.fold_left Extract.extract_trait_impl_register_names ctx
      trans_trait_impls
  in

  (* Open the output file *)
  (* First compute the filename by replacing the extension and converting the
   * case (rust module names are snake case) *)
  let namespace, crate_name, extract_filebasename =
    match Filename.chop_suffix_opt ~suffix:".llbc" filename with
    | None ->
        (* Note that we already checked the suffix upon opening the file *)
        raise (Failure "Unreachable")
    | Some filename ->
        (* Retrieve the file basename *)
        let basename = Filename.basename filename in
        (* Convert the case *)
        let crate_name = StringUtils.to_camel_case basename in
        let crate_name =
          if Config.backend () = HOL4 then
            StringUtils.lowercase_first_letter crate_name
          else crate_name
        in
        (* We use the raw crate name for the namespaces *)
        let namespace =
          match Config.backend () with
          | FStar | Coq | HOL4 -> crate.name
          | Lean -> crate.name
        in
        (* Concatenate *)
        (namespace, crate_name, Filename.concat dest_dir crate_name)
  in

  let mkdir_if dest_dir =
    if not (Sys.file_exists dest_dir) then (
      log#linfo (lazy ("Creating missing directory: " ^ dest_dir));
      (* Create a directory with *default* permissions *)
      Core_unix.mkdir_p dest_dir)
  in

  (* Create the directory, if necessary *)
  mkdir_if dest_dir;

  let needs_clauses_module =
    !Config.extract_decreases_clauses
    && not (PureUtils.FunLoopIdSet.is_empty rec_functions)
  in

  (* Lean reflects the module hierarchy within the filesystem, so we need to
     create more directories *)
  if Config.backend () = Lean then (
    let ( ^^ ) = Filename.concat in
    if !Config.split_files then mkdir_if (dest_dir ^^ crate_name);
    if needs_clauses_module then (
      assert !Config.split_files;
      mkdir_if (dest_dir ^^ crate_name ^^ "Clauses")));

  (* Copy the "Primitives" file, if necessary *)
  let _ =
    (* Retrieve the executable's directory *)
    let exe_dir = Filename.dirname Sys.argv.(0) in
    let primitives_src_dest =
      match Config.backend () with
      | FStar -> Some ("/backends/fstar/Primitives.fst", "Primitives.fst")
      | Coq -> Some ("/backends/coq/Primitives.v", "Primitives.v")
      | Lean -> None
      | HOL4 -> None
    in
    match primitives_src_dest with
    | None -> ()
    | Some (primitives_src, primitives_destname) -> (
        try
          (* TODO: stop copying the primitives file *)
          let src = open_in (exe_dir ^ primitives_src) in
          let tgt_filename = Filename.concat dest_dir primitives_destname in
          let tgt = open_out tgt_filename in
          (* Very annoying: I couldn't find a "cp" function in the OCaml libraries... *)
          try
            while true do
              (* We copy line by line *)
              let line = input_line src in
              Printf.fprintf tgt "%s\n" line
            done
          with End_of_file ->
            close_in src;
            close_out tgt;
            log#linfo (lazy ("Copied:    " ^ tgt_filename))
        with Sys_error _ ->
          log#error
            "Could not copy the primitives file: %s.\n\
             You will have to copy it/set up the project by hand."
            primitives_src)
  in

  (* Extract the file(s) *)
  let module_delimiter =
    match Config.backend () with
    | FStar -> "."
    | Coq -> "_"
    | Lean -> "."
    | HOL4 -> "_"
  in
  let file_delimiter =
    if Config.backend () = Lean then "/" else module_delimiter
  in
  (* File extension for the "regular" modules *)
  let ext =
    match Config.backend () with
    | FStar -> ".fst"
    | Coq -> ".v"
    | Lean -> ".lean"
    | HOL4 -> "Script.sml"
  in
  (* File extension for the opaque module *)
  let opaque_ext =
    match Config.backend () with
    | FStar -> ".fsti"
    | Coq -> ".v"
    | Lean -> ".lean"
    | HOL4 -> "Script.sml"
  in

  (* Extract one or several files, depending on the configuration *)
  (if !Config.split_files then (
     let base_gen_config =
       {
         extract_types = false;
         extract_decreases_clauses = !Config.extract_decreases_clauses;
         extract_template_decreases_clauses = false;
         extract_fun_decls = false;
         extract_trait_decls = false;
         extract_trait_impls = false;
         extract_transparent = true;
         extract_opaque = false;
         extract_state_type = false;
         extract_globals = false;
         interface = false;
         test_trans_unit_functions = false;
       }
     in

     (* Check if there are opaque types and functions - in which case we need
      * to split *)
     let has_opaque_types, has_opaque_funs =
       crate_has_opaque_non_builtin_decls ctx true
     in
     let has_opaque_types = has_opaque_types || !Config.use_state in

     (*
      * Extract the types
      *)
     (* If there are opaque types, we extract in an interface *)
     (* Extract the opaque type declarations, if needed *)
     let opaque_types_module =
       if has_opaque_types then (
         (* For F*, we generate an .fsti, and let the user write the .fst.
            For the other backends, we generate a template file as a model
            for the file the user has to provide. *)
         let module_suffix, opaque_imported_suffix, custom_msg =
           match Config.backend () with
           | FStar ->
               ("TypesExternal", "TypesExternal", ": external type declarations")
           | HOL4 | Coq | Lean ->
               ( (* The name of the file we generate *)
                 "TypesExternal_Template",
                 (* The name of the file that will be imported by the Types
                    module, and that the user has to provide. *)
                 "TypesExternal",
                 ": external types.\n\
                  -- This is a template file: rename it to \
                  \"TypesExternal.lean\" and fill the holes." )
         in
         let opaque_filename =
           extract_filebasename ^ file_delimiter ^ module_suffix ^ opaque_ext
         in
         let opaque_module = crate_name ^ module_delimiter ^ module_suffix in
         let opaque_imported_module =
           crate_name ^ module_delimiter ^ opaque_imported_suffix
         in
         let opaque_config =
           {
             base_gen_config with
             extract_opaque = true;
             extract_transparent = false;
             extract_types = true;
             extract_trait_decls = true;
             extract_state_type = !Config.use_state;
             interface = true;
           }
         in
         let file_info =
           {
             filename = opaque_filename;
             namespace;
             in_namespace = false;
             open_namespace = false;
             crate_name;
             rust_module_name = crate.name;
             module_name = opaque_module;
             custom_msg;
             custom_imports = [];
             custom_includes = [];
           }
         in
         extract_file opaque_config ctx file_info;
         (* Return the additional dependencies *)
         [ opaque_imported_module ])
       else []
     in

     (* Extract the non opaque types *)
     let types_filename_ext =
       match Config.backend () with
       | FStar -> ".fst"
       | Coq -> ".v"
       | Lean -> ".lean"
       | HOL4 -> "Script.sml"
     in
     let types_filename =
       extract_filebasename ^ file_delimiter ^ "Types" ^ types_filename_ext
     in
     let types_module = crate_name ^ module_delimiter ^ "Types" in
     let types_config =
       {
         base_gen_config with
         extract_types = true;
         extract_trait_decls = true;
         extract_opaque = false;
         interface = has_opaque_types;
       }
     in
     let file_info =
       {
         filename = types_filename;
         namespace;
         in_namespace = true;
         open_namespace = false;
         crate_name;
         rust_module_name = crate.name;
         module_name = types_module;
         custom_msg = ": type definitions";
         custom_imports = [];
         custom_includes = opaque_types_module;
       }
     in
     extract_file types_config ctx file_info;

     (* Extract the template clauses *)
     (if needs_clauses_module && !Config.extract_template_decreases_clauses then
        let template_clauses_filename =
          extract_filebasename ^ file_delimiter ^ "Clauses" ^ file_delimiter
          ^ "Template" ^ ext
        in
        let template_clauses_module =
          crate_name ^ module_delimiter ^ "Clauses" ^ module_delimiter
          ^ "Template"
        in
        let template_clauses_config =
          { base_gen_config with extract_template_decreases_clauses = true }
        in
        let file_info =
          {
            filename = template_clauses_filename;
            namespace;
            in_namespace = true;
            open_namespace = false;
            crate_name;
            rust_module_name = crate.name;
            module_name = template_clauses_module;
            custom_msg = ": templates for the decreases clauses";
            custom_imports = [ types_module ];
            custom_includes = [];
          }
        in
        extract_file template_clauses_config ctx file_info);

     (* Extract the opaque fun declarations, if needed *)
     let opaque_funs_module =
       if has_opaque_funs then (
         (* For F*, we generate an .fsti, and let the user write the .fst.
            For the other backends, we generate a template file as a model
            for the file the user has to provide. *)
         let module_suffix, opaque_imported_suffix, custom_msg =
           match Config.backend () with
           | FStar ->
               ( "FunsExternal",
                 "FunsExternal",
                 ": external function declarations" )
           | HOL4 | Coq | Lean ->
               ( (* The name of the file we generate *)
                 "FunsExternal_Template",
                 (* The name of the file that will be imported by the Funs
                    module, and that the user has to provide. *)
                 "FunsExternal",
                 ": external functions.\n\
                  -- This is a template file: rename it to \
                  \"FunsExternal.lean\" and fill the holes." )
         in
         let opaque_filename =
           extract_filebasename ^ file_delimiter ^ module_suffix ^ opaque_ext
         in
         let opaque_module = crate_name ^ module_delimiter ^ module_suffix in
         let opaque_imported_module =
           crate_name ^ module_delimiter ^ opaque_imported_suffix
         in
         let opaque_config =
           {
             base_gen_config with
             extract_fun_decls = true;
             extract_trait_impls = true;
             extract_globals = true;
             extract_transparent = false;
             extract_opaque = true;
             interface = true;
           }
         in
         let file_info =
           {
             filename = opaque_filename;
             namespace;
             in_namespace = false;
             open_namespace = true;
             crate_name;
             rust_module_name = crate.name;
             module_name = opaque_module;
             custom_msg;
             custom_imports = [];
             custom_includes = [ types_module ];
           }
         in
         extract_file opaque_config ctx file_info;
         (* Return the additional dependencies *)
         [ opaque_imported_module ])
       else []
     in

     (* Extract the functions *)
     let fun_filename = extract_filebasename ^ file_delimiter ^ "Funs" ^ ext in
     let fun_module = crate_name ^ module_delimiter ^ "Funs" in
     let fun_config =
       {
         base_gen_config with
         extract_fun_decls = true;
         extract_trait_impls = true;
         extract_globals = true;
         test_trans_unit_functions = !Config.test_trans_unit_functions;
       }
     in
     let clauses_module =
       if needs_clauses_module then
         let clauses_submodule =
           if Config.backend () = Lean then module_delimiter ^ "Clauses" else ""
         in
         [ crate_name ^ clauses_submodule ^ module_delimiter ^ "Clauses" ]
       else []
     in
     let file_info =
       {
         filename = fun_filename;
         namespace;
         in_namespace = true;
         open_namespace = false;
         crate_name;
         rust_module_name = crate.name;
         module_name = fun_module;
         custom_msg = ": function definitions";
         custom_imports = [];
         custom_includes =
           [ types_module ] @ opaque_funs_module @ clauses_module;
       }
     in
     extract_file fun_config ctx file_info)
   else
     let gen_config =
       {
         extract_types = true;
         extract_decreases_clauses = !Config.extract_decreases_clauses;
         extract_template_decreases_clauses =
           !Config.extract_template_decreases_clauses;
         extract_fun_decls = true;
         extract_trait_decls = true;
         extract_trait_impls = true;
         extract_transparent = true;
         extract_opaque = true;
         extract_state_type = !Config.use_state;
         extract_globals = true;
         interface = false;
         test_trans_unit_functions = !Config.test_trans_unit_functions;
       }
     in
     let file_info =
       {
         filename = extract_filebasename ^ ext;
         namespace;
         in_namespace = true;
         open_namespace = false;
         crate_name;
         rust_module_name = crate.name;
         module_name = crate_name;
         custom_msg = "";
         custom_imports = [];
         custom_includes = [];
       }
     in
     extract_file gen_config ctx file_info);

  (* Generate the build file *)
  match Config.backend () with
  | Coq | FStar | HOL4 ->
      ()
      (* Nothing to do - TODO: we might want to generate the _CoqProject file for Coq.
         But then we can't modify it if we want to add more files for the proofs
         for instance. But we might want to put the proofs elsewhere anyway.
         Remark: there is the same problem for Lean actually.
         Maybe generate it if the user asks for it?
      *)
  | Lean ->
      (*
       * Generate the library entry point, if the crate is split between
       * different files.
       *)
      if !Config.split_files && !Config.generate_lib_entry_point then (
        let filename = Filename.concat dest_dir (crate_name ^ ".lean") in
        let out = open_out filename in
        (* Write *)
        Printf.fprintf out "import %s.Funs\n" crate_name;
        (* Flush and close the file, log *)
        close_out out;
        log#linfo (lazy ("Generated: " ^ filename)));

      (*
       * Generate the lakefile.lean file, if the user asks for it
       *)
      if !Config.lean_gen_lakefile then (
        (* Open the file *)
        let filename = Filename.concat dest_dir "lakefile.lean" in
        let out = open_out filename in

        (* Generate the content *)
        Printf.fprintf out "import Lake\nopen Lake DSL\n\n";
        Printf.fprintf out "require mathlib from git\n";
        Printf.fprintf out
          "  \"https://github.com/leanprover-community/mathlib4.git\"\n\n";

        let package_name = StringUtils.to_snake_case crate_name in
        Printf.fprintf out "package «%s» {}\n\n" package_name;

        Printf.fprintf out "@[default_target]\nlean_lib «%s» {}\n" crate_name;

        (* No default target for now.
           Format would be:
           {[
             @[default_target]
               lean_exe «package_name» {
               root := `Main
             }
           ]}
        *)

        (* Flush and close the file *)
        close_out out;

        (* Logging *)
        log#linfo (lazy ("Generated: " ^ filename)))