Release coccinelle-0.2.4rc6

[bpt/coccinelle.git] / engine / transformation_c.ml

(*
 * Copyright 2010, INRIA, University of Copenhagen
 * Julia Lawall, Rene Rydhof Hansen, Gilles Muller, Nicolas Palix
 * Copyright 2005-2009, Ecole des Mines de Nantes, University of Copenhagen
 * Yoann Padioleau, Julia Lawall, Rene Rydhof Hansen, Henrik Stuart, Gilles Muller, Nicolas Palix
 * This file is part of Coccinelle.
 *
 * Coccinelle is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, according to version 2 of the License.
 *
 * Coccinelle is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Coccinelle.  If not, see <http://www.gnu.org/licenses/>.
 *
 * The authors reserve the right to distribute this or future versions of
 * Coccinelle under other licenses.
 *)


1(* Yoann Padioleau
 *
 * Copyright (C) 2006, 2007 Ecole des Mines de Nantes
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License (GPL)
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * file license.txt for more details.
 *
 * This file was part of Coccinelle.
 *)
open Common

module F = Control_flow_c

(*****************************************************************************)
(* The functor argument  *)
(*****************************************************************************)

(* info passed recursively in monad in addition to binding *)
type xinfo = {
  optional_storage_iso : bool;
  optional_qualifier_iso : bool;
  value_format_iso : bool;
  current_rule_name : string; (* used for errors *)
  index : int list (* witness tree indices *)
}

module XTRANS = struct

  (* ------------------------------------------------------------------------*)
  (* Combinators history *)
  (* ------------------------------------------------------------------------*)
  (*
   * version0:
   *  type ('a, 'b) transformer =
   *    'a -> 'b -> Lib_engine.metavars_binding -> 'b
   *  exception NoMatch
   *
   * version1:
   *   type ('a, 'b) transformer =
   *    'a -> 'b -> Lib_engine.metavars_binding -> 'b option
   * use an exception monad
   *
   * version2:
   *    type tin = Lib_engine.metavars_binding
   *)

  (* ------------------------------------------------------------------------*)
  (* Standard type and operators  *)
  (* ------------------------------------------------------------------------*)

  type tin = {
    extra: xinfo;
    binding: Lib_engine.metavars_binding;
    binding0: Lib_engine.metavars_binding; (* inherited variable *)
  }
  type 'x tout = 'x option

  type ('a, 'b) matcher = 'a -> 'b  -> tin -> ('a * 'b) tout

  let (>>=) m f = fun tin ->
     match m tin with
     | None -> None
     | Some (a,b) -> f a b tin

  let return = fun x -> fun tin ->
    Some x

  (* can have fail in transform now that the process is deterministic ? *)
  let fail = fun tin ->
    None

  let (>||>) m1 m2 = fun tin ->
    match m1 tin with
    | None -> m2 tin
    | Some x -> Some x (* stop as soon as have found something *)

  let (>|+|>) m1 m2 = m1 >||> m2

  let (>&&>) f m = fun tin ->
    if f tin then m tin else fail tin

  let optional_storage_flag f = fun tin ->
    f (tin.extra.optional_storage_iso) tin

  let optional_qualifier_flag f = fun tin ->
    f (tin.extra.optional_qualifier_iso) tin

  let value_format_flag f = fun tin ->
    f (tin.extra.value_format_iso) tin

  let mode = Cocci_vs_c.TransformMode

  (* ------------------------------------------------------------------------*)
  (* Exp  *)
  (* ------------------------------------------------------------------------*)
  let cocciExp = fun expf expa node -> fun tin ->

    let bigf = {
      Visitor_c.default_visitor_c_s with
      Visitor_c.kexpr_s = (fun (k, bigf) expb ->
	match expf expa expb tin with
	| None -> (* failed *) k expb
	| Some (x, expb) -> expb);
    }
    in
    Some (expa, Visitor_c.vk_node_s bigf node)


  (* same as cocciExp, but for expressions in an expression, not expressions
     in a node *)
  let cocciExpExp = fun expf expa expb -> fun tin ->

    let bigf = {
      Visitor_c.default_visitor_c_s with
      Visitor_c.kexpr_s = (fun (k, bigf) expb ->
	match expf expa expb tin with
	| None -> (* failed *) k expb
	| Some (x, expb) -> expb);
    }
    in
    Some (expa, Visitor_c.vk_expr_s bigf expb)


  let cocciTy = fun expf expa node -> fun tin ->

    let bigf = {
      Visitor_c.default_visitor_c_s with
      Visitor_c.ktype_s = (fun (k, bigf) expb ->
	match expf expa expb tin with
	| None -> (* failed *) k expb
	| Some (x, expb) -> expb);
    }
    in
    Some (expa, Visitor_c.vk_node_s bigf node)

  let cocciInit = fun expf expa node -> fun tin ->

    let bigf = {
      Visitor_c.default_visitor_c_s with
      Visitor_c.kini_s = (fun (k, bigf) expb ->
	match expf expa expb tin with
	| None -> (* failed *) k expb
	| Some (x, expb) -> expb);
    }
    in
    Some (expa, Visitor_c.vk_node_s bigf node)


  (* ------------------------------------------------------------------------*)
  (* Tokens *)
  (* ------------------------------------------------------------------------*)
   let check_pos info mck pos =
     match mck with
     | Ast_cocci.PLUS _ -> raise Impossible
     | Ast_cocci.CONTEXT (Ast_cocci.FixPos (i1,i2),_)
     | Ast_cocci.MINUS   (Ast_cocci.FixPos (i1,i2),_,_,_) ->
         pos <= i2 && pos >= i1
     | Ast_cocci.CONTEXT (Ast_cocci.DontCarePos,_)
     | Ast_cocci.MINUS   (Ast_cocci.DontCarePos,_,_,_) ->
         true
     | _ ->
	 match info with
	   Some info ->
	     failwith
	       (Printf.sprintf
		  "weird: dont have position info for the mcodekind in line %d column %d"
		  info.Ast_cocci.line info.Ast_cocci.column)
	 | None ->
	     failwith "weird: dont have position info for the mcodekind"


  let tag_with_mck mck ib = fun tin ->

    let cocciinforef = ib.Ast_c.cocci_tag in
    let (oldmcode, oldenvs) = Ast_c.mcode_and_env_of_cocciref cocciinforef in

    let mck =
      (* coccionly:
      if !Flag_parsing_cocci.sgrep_mode
      then Sgrep.process_sgrep ib mck
      else
      *)
        mck
    in
    (match mck, Ast_c.pinfo_of_info ib with
    | _,                  Ast_c.AbstractLineTok _ -> raise Impossible
    | Ast_cocci.MINUS(_), Ast_c.ExpandedTok _ ->
        failwith ("try to delete an expanded token: " ^ (Ast_c.str_of_info ib))
    | _ -> ()
    );

    let many_count = function
	Ast_cocci.BEFORE(_,Ast_cocci.MANY) | Ast_cocci.AFTER(_,Ast_cocci.MANY)
      |	 Ast_cocci.BEFOREAFTER(_,_,Ast_cocci.MANY) -> true
      |	_ -> false in

    (match (oldmcode,mck) with
    | (Ast_cocci.CONTEXT(_,Ast_cocci.NOTHING),      _) ->
	(* nothing there, so take the new stuff *)
	let update_inst inst = function
	    Ast_cocci.MINUS (pos,_,adj,any_xxs) ->
	      Ast_cocci.MINUS (pos,inst,adj,any_xxs)
	  | mck -> mck in
        cocciinforef := Some (update_inst tin.extra.index mck, [tin.binding])
    | (_,   Ast_cocci.CONTEXT(_,Ast_cocci.NOTHING)) ->
	(* can this case occur? stay with the old stuff *)
	()
    | (Ast_cocci.MINUS(old_pos,old_inst,old_adj,[]),
       Ast_cocci.MINUS(new_pos,new_inst,new_adj,[]))
	when old_pos = new_pos &&
	  (List.mem tin.binding oldenvs or !Flag.sgrep_mode2)
	    (* no way to combine adjacency information, just drop one *)
      ->
        cocciinforef := Some
	  (Ast_cocci.MINUS
	     (old_pos,Common.union_set old_inst new_inst,old_adj,[]),
	   [tin.binding]);
        (if !Flag_matcher.show_misc
        then pr2 "already tagged but only removed, so safe")

    | (Ast_cocci.CONTEXT(old_pos,old_modif),
       Ast_cocci.CONTEXT(new_pos,new_modif))
	when old_pos = new_pos &&
	  old_modif = new_modif && many_count old_modif ->
	    (* iteration only allowed on context; no way to replace something
	       more than once; now no need for iterable; just check a flag *)

          cocciinforef :=
	    Some(Ast_cocci.CONTEXT(old_pos,old_modif),tin.binding::oldenvs)

    | _ ->
          (* coccionly:
          if !Flag.sgrep_mode2
          then ib (* safe *)
          else
          *)
             begin
            (* coccionly:
               pad: if dont want cocci write:
                failwith
	        (match Ast_c.pinfo_of_info ib with
		  Ast_c.FakeTok _ -> "already tagged fake token"
             *)
	       let pm str mcode env =
		 Printf.sprintf
		   "%s modification:\n%s\nAccording to environment %d:\n%s\n"
		   str
		   (Common.format_to_string
		      (function _ ->
			Pretty_print_cocci.print_mcodekind mcode))
		   (List.length env)
		   (String.concat "\n"
		      (List.map
			 (function ((r,vr),vl) ->
			   Printf.sprintf "   %s.%s -> %s" r vr
			     (Common.format_to_string
				(function _ ->
				  Pretty_print_engine.pp_binding_kind vl)))
			 env)) in
	       flush stdout; flush stderr;
	       Common.pr2
		 ("\n"^ (String.concat "\n"
			   (List.map (pm "previous" oldmcode) oldenvs)) ^ "\n"
		  ^ (pm "current" mck tin.binding));
               failwith
	         (match Ast_c.pinfo_of_info ib with
		   Ast_c.FakeTok _ ->
		     Common.sprintf "%s: already tagged fake token\n"
		       tin.extra.current_rule_name
		| _ ->
		    Printf.sprintf
		      "%s: already tagged token:\nC code context\n%s"
		      tin.extra.current_rule_name
	              (Common.error_message (Ast_c.file_of_info ib)
			 (Ast_c.str_of_info ib, Ast_c.opos_of_info ib)))
            end);
    ib

  let tokenf ia ib = fun tin ->
    let (_,i,mck,_) = ia in
    let pos = Ast_c.info_to_fixpos ib in
    if check_pos (Some i) mck pos
    then return (ia, tag_with_mck mck ib tin) tin
    else fail tin

  let tokenf_mck mck ib = fun tin ->
    let pos = Ast_c.info_to_fixpos ib in
    if check_pos None mck pos
    then return (mck, tag_with_mck mck ib tin) tin
    else fail tin


  (* ------------------------------------------------------------------------*)
  (* Distribute mcode *)
  (* ------------------------------------------------------------------------*)

  (* When in the SP we attach something to a metavariable, or delete it, as in
   * - S
   * + foo();
   * we have to minusize all the token that compose S in the C code, and
   * attach the 'foo();'  to the right token, the one at the very right.
   *)

  type 'a distributer =
      (Ast_c.info -> Ast_c.info) *  (* what to do on left *)
      (Ast_c.info -> Ast_c.info) *  (* what to do on middle *)
      (Ast_c.info -> Ast_c.info) *  (* what to do on right *)
      (Ast_c.info -> Ast_c.info) -> (* what to do on both *)
      'a -> 'a

  let distribute_mck mcodekind distributef expr tin =
    match mcodekind with
    | Ast_cocci.MINUS (pos,_,adj,any_xxs) ->
	let inst = tin.extra.index in
        distributef (
          (fun ib ->
	    tag_with_mck (Ast_cocci.MINUS (pos,inst,adj,any_xxs)) ib tin),
          (fun ib ->
	    tag_with_mck (Ast_cocci.MINUS (pos,inst,adj,[])) ib tin),
          (fun ib ->
	    tag_with_mck (Ast_cocci.MINUS (pos,inst,adj,[])) ib tin),
          (fun ib ->
	    tag_with_mck (Ast_cocci.MINUS (pos,inst,adj,any_xxs)) ib tin)
        ) expr
    | Ast_cocci.CONTEXT (pos,any_befaft) ->
        (match any_befaft with
        | Ast_cocci.NOTHING -> expr

        | Ast_cocci.BEFORE (xxs,c) ->
            distributef (
              (fun ib -> tag_with_mck
                (Ast_cocci.CONTEXT (pos,Ast_cocci.BEFORE (xxs,c))) ib tin),
              (fun x -> x),
              (fun x -> x),
              (fun ib -> tag_with_mck
                (Ast_cocci.CONTEXT (pos,Ast_cocci.BEFORE (xxs,c))) ib tin)
            ) expr
        | Ast_cocci.AFTER (xxs,c) ->
            distributef (
              (fun x -> x),
              (fun x -> x),
              (fun ib -> tag_with_mck
                (Ast_cocci.CONTEXT (pos,Ast_cocci.AFTER (xxs,c))) ib tin),
              (fun ib -> tag_with_mck
                (Ast_cocci.CONTEXT (pos,Ast_cocci.AFTER (xxs,c))) ib tin)
            ) expr

        | Ast_cocci.BEFOREAFTER (xxs, yys, c) ->
            distributef (
              (fun ib -> tag_with_mck
                (Ast_cocci.CONTEXT (pos,Ast_cocci.BEFORE (xxs,c))) ib tin),
              (fun x -> x),
              (fun ib -> tag_with_mck
                (Ast_cocci.CONTEXT (pos,Ast_cocci.AFTER (yys,c))) ib tin),
              (fun ib -> tag_with_mck
                (Ast_cocci.CONTEXT (pos,Ast_cocci.BEFOREAFTER (xxs,yys,c)))
                ib tin)
            ) expr

        )
    | Ast_cocci.PLUS _ -> raise Impossible


  (* use new strategy, collect ii, sort, recollect and tag *)

  let mk_bigf (maxpos, minpos) (lop,mop,rop,bop) =
    let bigf = {
      Visitor_c.default_visitor_c_s with
        Visitor_c.kinfo_s = (fun (k,bigf) i ->
          let pos = Ast_c.info_to_fixpos i in
          match () with
          | _ when Ast_cocci.equal_pos pos maxpos &&
	      Ast_cocci.equal_pos pos minpos -> bop i
          | _ when Ast_cocci.equal_pos pos maxpos -> rop i
          | _ when Ast_cocci.equal_pos pos minpos -> lop i
          | _ -> mop i
        )
    } in
    bigf

  let distribute_mck_expr (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_expr_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_args (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_args_splitted_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_type (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_type_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_decl (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_decl_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_field (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_struct_field_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_ini (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_ini_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_inis (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_inis_splitted_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_param (maxpos, minpos) = fun (lop,mop,rop,bop) -> fun x ->
    Visitor_c.vk_param_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop)) x

  let distribute_mck_params (maxpos, minpos) = fun (lop,mop,rop,bop) ->fun x ->
    Visitor_c.vk_params_splitted_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop))
      x

  let distribute_mck_node (maxpos, minpos) = fun (lop,mop,rop,bop) ->fun x ->
    Visitor_c.vk_node_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop))
      x

  let distribute_mck_enum_fields (maxpos, minpos) =
    fun (lop,mop,rop,bop) ->fun x ->
      Visitor_c.vk_enum_fields_splitted_s
	(mk_bigf (maxpos, minpos) (lop,mop,rop,bop))
        x

  let distribute_mck_struct_fields (maxpos, minpos) =
    fun (lop,mop,rop,bop) ->fun x ->
      Visitor_c.vk_struct_fields_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop))
        x

  let distribute_mck_cst (maxpos, minpos) =
    fun (lop,mop,rop,bop) ->fun x ->
      Visitor_c.vk_cst_s (mk_bigf (maxpos, minpos) (lop,mop,rop,bop))
        x


  let distribute_mck_define_params (maxpos, minpos) = fun (lop,mop,rop,bop) ->
   fun x ->
    Visitor_c.vk_define_params_splitted_s
      (mk_bigf (maxpos, minpos) (lop,mop,rop,bop))
      x

   let get_pos mck =
     match mck with
     | Ast_cocci.PLUS _ -> raise Impossible
     | Ast_cocci.CONTEXT (Ast_cocci.FixPos (i1,i2),_)
     | Ast_cocci.MINUS   (Ast_cocci.FixPos (i1,i2),_,_,_) ->
         Ast_cocci.FixPos (i1,i2)
     | Ast_cocci.CONTEXT (Ast_cocci.DontCarePos,_)
     | Ast_cocci.MINUS   (Ast_cocci.DontCarePos,_,_,_) ->
         Ast_cocci.DontCarePos
     | _ -> failwith "weird: dont have position info for the mcodekind 2"

  let distrf (ii_of_x_f, distribute_mck_x_f) =
    fun ia x -> fun tin ->
    let mck = Ast_cocci.get_mcodekind ia in
    let (max, min) = Lib_parsing_c.max_min_by_pos (ii_of_x_f x)
    in
    if
      (* bug: check_pos mck max && check_pos mck min
       *
       * if do that then if have - f(...); and in C f(1,2); then we
       * would get a "already tagged" because the '...' would sucess in
       * transformaing both '1' and '1,2'. So being in the range is not
       * enough. We must be equal exactly to the range!
       *)
      (match get_pos mck with
      | Ast_cocci.DontCarePos -> true
      | Ast_cocci.FixPos (i1, i2) ->
          i1 =*= min && i2 =*= max
      | _ -> raise Impossible
      )

    then
      return (
        ia,
        distribute_mck mck (distribute_mck_x_f (max,min))  x tin
      ) tin
    else fail tin


  let distrf_e    = distrf (Lib_parsing_c.ii_of_expr,  distribute_mck_expr)
  let distrf_args = distrf (Lib_parsing_c.ii_of_args,  distribute_mck_args)
  let distrf_type = distrf (Lib_parsing_c.ii_of_type,  distribute_mck_type)
  let distrf_param  = distrf (Lib_parsing_c.ii_of_param, distribute_mck_param)
  let distrf_params = distrf (Lib_parsing_c.ii_of_params,distribute_mck_params)
  let distrf_ini = distrf (Lib_parsing_c.ii_of_ini,distribute_mck_ini)
  let distrf_inis = distrf (Lib_parsing_c.ii_of_inis,distribute_mck_inis)
  let distrf_decl = distrf (Lib_parsing_c.ii_of_decl,distribute_mck_decl)
  let distrf_field = distrf (Lib_parsing_c.ii_of_field,distribute_mck_field)
  let distrf_node = distrf (Lib_parsing_c.ii_of_node,distribute_mck_node)
  let distrf_enum_fields =
    distrf (Lib_parsing_c.ii_of_enum_fields, distribute_mck_enum_fields)
  let distrf_struct_fields =
    distrf (Lib_parsing_c.ii_of_struct_fields, distribute_mck_struct_fields)
  let distrf_cst =
    distrf (Lib_parsing_c.ii_of_cst, distribute_mck_cst)
  let distrf_define_params =
    distrf (Lib_parsing_c.ii_of_define_params,distribute_mck_define_params)


  (* ------------------------------------------------------------------------*)
  (* Environment *)
  (* ------------------------------------------------------------------------*)
  let meta_name_to_str (s1, s2) = s1 ^ "." ^ s2

  let envf keep inherited = fun (s, value, _) f tin ->
    let s = Ast_cocci.unwrap_mcode s in
    let v =
      if keep =*= Type_cocci.Saved
      then (
        try Some (List.assoc s tin.binding)
        with Not_found ->
          pr2(sprintf
		"Don't find value for metavariable %s in the environment"
                (meta_name_to_str s));
          None)
      else
        (* not raise Impossible! *)
        Some (value)
    in
    match v with
    | None -> fail tin
    | Some (value') ->

        (* Ex: in cocci_vs_c someone wants to add a binding. Here in
         * transformation3 the value for this var may be already in the
         * env, because for instance its value were fixed in a previous
         * SmPL rule. So here we want to check that this is the same value.
         * If forget to do the check, what can happen ? Because of Exp
         * and other disjunctive feature of cocci_vs_c (>||>), we
         * may accept a match at a wrong position. Maybe later this
         * will be detected via the pos system on tokens, but maybe
         * not. So safer to keep the check.
         *)

        (*f () tin*)
	let equal =
	  if inherited
	  then Cocci_vs_c.equal_inh_metavarval
	  else Cocci_vs_c.equal_metavarval in
        if equal value value'
        then f () tin
        else fail tin


  let check_idconstraint matcher c id = fun f tin -> f () tin
  let check_constraints_ne matcher constraints exp = fun f tin -> f () tin

  (* ------------------------------------------------------------------------*)
  (* Environment, allbounds *)
  (* ------------------------------------------------------------------------*)
  let (all_bound : Ast_cocci.meta_name list -> tin -> bool) = fun l tin ->
    true (* in transform we don't care ? *)

end

(*****************************************************************************)
(* Entry point  *)
(*****************************************************************************)
module TRANS  = Cocci_vs_c.COCCI_VS_C (XTRANS)


let transform_re_node a b tin =
  match TRANS.rule_elem_node a b tin with
  | None -> raise Impossible
  | Some (_sp, b') -> b'

let (transform2: string (* rule name *) -> string list (* dropped_isos *) ->
  Lib_engine.metavars_binding (* inherited bindings *) ->
  Lib_engine.numbered_transformation_info -> F.cflow -> F.cflow) =
 fun rule_name dropped_isos binding0 xs cflow ->

   let extra = {
     optional_storage_iso   = not(List.mem "optional_storage" dropped_isos);
     optional_qualifier_iso = not(List.mem "optional_qualifier" dropped_isos);
     value_format_iso = not(List.mem "value_format" dropped_isos);
     current_rule_name = rule_name;
     index = [];
   } in

  (* find the node, transform, update the node,  and iter for all elements *)

   xs +> List.fold_left (fun acc (index, (nodei, binding, rule_elem)) ->
      (* subtil: not cflow#nodes but acc#nodes *)
      let node  = acc#nodes#assoc nodei in

      if !Flag.show_transinfo
      then pr2 "transform one node";

      let tin = {
        XTRANS.extra = {extra with index = index};
        XTRANS.binding = binding0@binding;
        XTRANS.binding0 = []; (* not used - everything constant for trans *)
      } in

      let node' = transform_re_node rule_elem node tin in

      (* assert that have done something. But with metaruleElem sometimes
         dont modify fake nodes. So special case before on Fake nodes. *)
      (match F.unwrap node with
      | F.Enter | F.Exit | F.ErrorExit
      | F.EndStatement _ | F.CaseNode _
      | F.Fake
      | F.TrueNode | F.FalseNode | F.AfterNode | F.FallThroughNode
          -> ()
      | _ -> () (* assert (not (node =*= node')); *)
      );

      (* useless, we dont go back from flow to ast now *)
      (* let node' = lastfix_comma_struct node' in *)

      acc#replace_node (nodei, node');
      acc
   ) cflow



let transform a b c d e =
  Common.profile_code "Transformation3.transform"
    (fun () -> transform2 a b c d e)