builtin_attributes.ml

(***********************************************************************)
(*                                                                     *)
(*                                OCaml                                *)
(*                                                                     *)
(*                        Alain Frisch, LexiFi                         *)
(*                                                                     *)
(*  Copyright 2012 Institut National de Recherche en Informatique et   *)
(*  en Automatique.  All rights reserved.  This file is distributed    *)
(*  under the terms of the Q Public License version 1.0.               *)
(*                                                                     *)
(***********************************************************************)

open Asttypes
open Parsetree

let string_of_cst = function
  | Pconst_string(s, _) -> Some s
  | _ -> None

let string_of_payload = function
  | PStr[{pstr_desc=Pstr_eval({pexp_desc=Pexp_constant c},_)}] ->
      string_of_cst c
  | _ -> None

let rec error_of_extension ext =
  match ext with
  | ({txt = ("ocaml.error"|"error") as txt; loc}, p) ->
    let rec sub_from inner =
      match inner with
      | {pstr_desc=Pstr_extension (ext, _)} :: rest ->
          error_of_extension ext :: sub_from rest
      | {pstr_loc} :: rest ->
          (Location.errorf ~loc
             "Invalid syntax for sub-error of extension '%s'." txt) ::
            sub_from rest
      | [] -> []
    in
    begin match p with
    | PStr({pstr_desc=Pstr_eval
              ({pexp_desc=Pexp_constant(Pconst_string(msg,_))}, _)}::
           {pstr_desc=Pstr_eval
              ({pexp_desc=Pexp_constant(Pconst_string(if_highlight,_))}, _)}::
           inner) ->
        Location.error ~loc ~if_highlight ~sub:(sub_from inner) msg
    | PStr({pstr_desc=Pstr_eval
              ({pexp_desc=Pexp_constant(Pconst_string(msg,_))}, _)}::inner) ->
        Location.error ~loc ~sub:(sub_from inner) msg
    | _ -> Location.errorf ~loc "Invalid syntax for extension '%s'." txt
    end
  | ({txt; loc}, _) ->
      Location.errorf ~loc "Uninterpreted extension '%s'." txt

let rec deprecated_of_attrs = function
  | [] -> None
  | ({txt = "ocaml.deprecated"|"deprecated"; _}, p) :: _ ->
      begin match string_of_payload p with
      | Some txt ->  Some txt
      | None -> Some ""
      end
  | _ :: tl -> deprecated_of_attrs tl

let check_deprecated loc attrs s =
  match deprecated_of_attrs attrs with
  | None -> ()
  | Some "" -> Location.prerr_warning loc (Warnings.Deprecated s)
  | Some txt ->
      Location.prerr_warning loc (Warnings.Deprecated (s ^ "\n" ^ txt))

let rec check_deprecated_mutable loc attrs s =
  match attrs with
  | [] -> ()
  | ({txt = "ocaml.deprecated_mutable"|"deprecated_mutable"; _}, p) :: _ ->
      let txt =
        match string_of_payload p with
        | Some txt -> "\n" ^ txt
        | None -> ""
      in
      Location.prerr_warning loc
        (Warnings.Deprecated (Printf.sprintf "mutating field %s%s"
           s txt))
  | _ :: tl -> check_deprecated_mutable loc tl s

let rec deprecated_of_sig = function
  | {psig_desc = Psig_attribute a} :: tl ->
      begin match deprecated_of_attrs [a] with
      | None -> deprecated_of_sig tl
      | Some _ as r -> r
      end
  | _ -> None


let rec deprecated_of_str = function
  | {pstr_desc = Pstr_attribute a} :: tl ->
      begin match deprecated_of_attrs [a] with
      | None -> deprecated_of_str tl
      | Some _ as r -> r
      end
  | _ -> None


let emit_external_warnings =
  (* Note: this is run as a preliminary pass when type-checking an
     interface or implementation.  This allows to cover all kinds of
     attributes, but the drawback is that it doesn't take local
     configuration of warnings (with '@@warning'/'@@warnerror'
     attributes) into account.  We should rather check for
     'ppwarning' attributes during the actual type-checking, making
     sure to cover all contexts (easier and more ugly alternative:
     duplicate here the logic which control warnings locally). *)
  let open Ast_iterator in
  {
    default_iterator with
    attribute = (fun _ a ->
        match a with
        | {txt="ocaml.ppwarning"|"ppwarning"},
          PStr[{pstr_desc=Pstr_eval({pexp_desc=Pexp_constant
                                         (Pconst_string (s, _))},_);
                pstr_loc}] ->
            Location.prerr_warning pstr_loc (Warnings.Preprocessor s)
        | _ -> ()
      )
  }


let warning_scope = ref []

let warning_enter_scope () =
  warning_scope := (Warnings.backup ()) :: !warning_scope
let warning_leave_scope () =
  match !warning_scope with
  | [] -> assert false
  | hd :: tl ->
      Warnings.restore hd;
      warning_scope := tl

let warning_attribute attrs =
  let process loc txt errflag payload =
    match string_of_payload payload with
    | Some s ->
        begin try Warnings.parse_options errflag s
        with Arg.Bad _ ->
          Location.prerr_warning loc
            (Warnings.Attribute_payload
               (txt, "Ill-formed list of warnings"))
        end
    | None ->
        Location.prerr_warning loc
          (Warnings.Attribute_payload
             (txt, "A single string literal is expected"))
  in
  List.iter
    (function
      | ({txt = ("ocaml.warning"|"warning") as txt; loc}, payload) ->
          process loc txt false payload
      | ({txt = ("ocaml.warnerror"|"warnerror") as txt; loc}, payload) ->
          process loc txt true payload
      | _ ->
          ()
    )
    attrs

let with_warning_attribute attrs f =
  try
    warning_enter_scope ();
    warning_attribute attrs;
    let ret = f () in
    warning_leave_scope ();
    ret
  with exn ->
    warning_leave_scope ();
    raise exn


let warn_on_literal_pattern =
  List.exists
    (function
      | ({txt="ocaml.warn_on_literal_pattern"|"warn_on_literal_pattern"; _}, _)
        -> true
      | _ -> false
    )

let explicit_arity =
  List.exists
    (function
      | ({txt="ocaml.explicit_arity"|"explicit_arity"; _}, _) -> true
      | _ -> false
    )