dev-ml/js_of_ocaml: fix build with ocaml 4.03

Package-Manager: portage-2.2.28
Signed-off-by: Alexis Ballier <aballier@gentoo.org>

2 files changed, 1422 insertions, 0 deletions

diff --git a/dev-ml/js_of_ocaml/files/oc43.patch b/dev-ml/js_of_ocaml/files/oc43.patch
new file mode 100644
index 000000000000..face8101603f
--- /dev/null
+++ b/dev-ml/js_of_ocaml/files/oc43.patch
@@ -0,0 +1,1418 @@
+commit 3e4d39ece5a67bfc17f47c3da8a95ccca789abd5
+Author: Hugo Heuzard <hugo.heuzard@gmail.com>
+Date:   Mon Mar 28 23:35:47 2016 +0100
+
+    Deriving_json for ocaml 4.03
+    
+    move
+
+diff --git a/.gitignore b/.gitignore
+index 71e4ccf..ccbb796 100644
+--- a/.gitignore
++++ b/.gitignore
+@@ -58,6 +58,7 @@ benchmarks/results
+ benchmarks/config
+ lib/deriving_json/deriving_Json_lexer.ml
+ lib/ppx/ppx_js.ml
++lib/ppx/ppx_deriving_json.ml
+ lib/ppx/ppx_js
+ Makefile.local
+ 
+diff --git a/lib/ppx/ppx_deriving_json.cppo.ml b/lib/ppx/ppx_deriving_json.cppo.ml
+new file mode 100644
+index 0000000..814ed99
+--- /dev/null
++++ b/lib/ppx/ppx_deriving_json.cppo.ml
+@@ -0,0 +1,711 @@
++(* Js_of_ocaml
++ * http://www.ocsigen.org
++ * Copyright Vasilis Papavasileiou 2015
++ *
++ * This program is free software; you can redistribute it and/or modify
++ * it under the terms of the GNU Lesser General Public License as published by
++ * the Free Software Foundation, with linking exception;
++ * either version 2.1 of the License, or (at your option) any later version.
++ *
++ * 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
++ * GNU Lesser General Public License for more details.
++ *
++ * You should have received a copy of the GNU Lesser General Public License
++ * along with this program; if not, write to the Free Software
++ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
++ *)
++
++let deriver = "json"
++
++(* Copied (and adapted) this from ppx_deriving repo (commit
++   e2079fa8f3460055bf990461f295c6c4b391fafc) ; we get an empty set of
++   let bindings with ppx_deriving 3.0 *)
++let sanitize expr = [%expr
++  (let open! Ppx_deriving_runtime in [%e expr]) [@ocaml.warning "-A"]]
++
++let var_ptuple l =
++  List.map Ast_convenience.pvar l |> Ast_helper.Pat.tuple
++
++let map_loc f {Location.txt; loc} =
++  {Location.txt = f txt; loc}
++
++let suffix_lid {Location.txt; loc} ~suffix =
++  let txt = Ppx_deriving.mangle_lid (`Suffix suffix) txt in
++  Ast_helper.Exp.ident {txt; loc} ~loc
++
++let suffix_decl ({Parsetree.ptype_loc = loc} as d) ~suffix =
++  (let s =
++     Ppx_deriving.mangle_type_decl (`Suffix suffix) d |>
++     Longident.parse
++   in
++   Location.mkloc s loc) |> Ast_helper.Exp.ident ~loc
++
++let suffix_decl_p ({Parsetree.ptype_loc = loc} as d) ~suffix =
++  (let s = Ppx_deriving.mangle_type_decl (`Suffix suffix) d in
++   Location.mkloc s loc) |> Ast_helper.Pat.var ~loc
++
++let rec fresh_vars ?(acc = []) n =
++  if n <= 0 then
++    List.rev acc
++  else
++    let acc = Ppx_deriving.fresh_var acc :: acc in
++    fresh_vars ~acc (n - 1)
++
++let unreachable_case () =
++  Ast_helper.Exp.case [%pat? _ ] [%expr assert false]
++
++let label_of_constructor = map_loc (fun c -> Longident.Lident c)
++
++let wrap_write r ~pattern = [%expr fun buf [%p pattern] -> [%e r]]
++
++let buf_expand r = [%expr fun buf -> [%e r]]
++
++let seqlist = function
++  | h :: l ->
++    let f acc e = [%expr [%e acc]; [%e e]] in
++    List.fold_left f h l
++  | [] ->
++    [%expr ()]
++
++let check_record_fields =
++  List.iter @@ function
++  | {Parsetree.pld_mutable = Mutable} ->
++    Location.raise_errorf
++      "%s cannot be derived for mutable records" deriver
++  | {pld_type = {ptyp_desc = Ptyp_poly _}} ->
++    Location.raise_errorf
++      "%s cannot be derived for polymorphic records" deriver
++  | _ ->
++    ()
++
++let maybe_tuple_type = function
++  | [y] -> y
++  | l -> Ast_helper.Typ.tuple l
++
++let rec write_tuple_contents l ly ~tag ~poly =
++  let e =
++    let f v y =
++      let arg = Ast_convenience.evar v in
++      let e = write_body_of_type y ~arg ~poly in
++      [%expr Buffer.add_string buf ","; [%e e]]
++    in
++    List.map2 f l ly |> seqlist
++  and s = Ast_convenience.str ("[" ^ string_of_int tag) in [%expr
++    Buffer.add_string buf [%e s];
++    [%e e];
++    Buffer.add_string buf "]"]
++
++and write_body_of_tuple_type l ~arg ~poly ~tag =
++  let n = List.length l in
++  let vars = fresh_vars n in
++  let e = write_tuple_contents vars l ~tag ~poly
++  and p = var_ptuple vars in
++  [%expr let [%p p] = [%e arg] in [%e e]]
++
++and write_poly_case r ~arg ~poly =
++  match r with
++  | Parsetree.Rtag (label, _, _, l) ->
++    let i = Ppx_deriving.hash_variant label
++    and n = List.length l in
++    let v = Ppx_deriving.fresh_var [] in
++    let lhs =
++      (if n = 0 then None else Some (Ast_convenience.pvar v)) |>
++      Ast_helper.Pat.variant label
++    and rhs =
++      match l with
++      | [] ->
++        let e = Ast_convenience.int i in
++        [%expr Deriving_Json.Json_int.write buf [%e e]]
++      | _ ->
++        let l = [[%type: int]; maybe_tuple_type l]
++        and arg = Ast_helper.Exp.tuple Ast_convenience.[int i; evar v] in
++        write_body_of_tuple_type l ~arg ~poly ~tag:0
++    in
++    Ast_helper.Exp.case lhs rhs
++  | Rinherit ({ptyp_desc = Ptyp_constr (lid, _)} as y) ->
++    Ast_helper.Exp.case (Ast_helper.Pat.type_ lid)
++      (write_body_of_type y ~arg ~poly)
++  | Rinherit {ptyp_loc} ->
++    Location.raise_errorf ~loc:ptyp_loc
++      "%s write case cannot be derived" deriver
++
++and write_body_of_type y ~arg ~poly =
++  match y with
++  | [%type: unit] ->
++    [%expr Deriving_Json.Json_unit.write buf [%e arg]]
++  | [%type: int] ->
++    [%expr Deriving_Json.Json_int.write buf [%e arg]]
++  | [%type: int32] | [%type: Int32.t] ->
++    [%expr Deriving_Json.Json_int32.write buf [%e arg]]
++  | [%type: int64] | [%type: Int64.t] ->
++    [%expr Deriving_Json.Json_int64.write buf [%e arg]]
++  | [%type: nativeint] | [%type: Nativeint.t] ->
++    [%expr Deriving_Json.Json_nativeint.write buf [%e arg]]
++  | [%type: float] ->
++    [%expr Deriving_Json.Json_float.write buf [%e arg]]
++  | [%type: bool] ->
++    [%expr Deriving_Json.Json_bool.write buf [%e arg]]
++  | [%type: char] ->
++    [%expr Deriving_Json.Json_char.write buf [%e arg]]
++  | [%type: string] ->
++    [%expr Deriving_Json.Json_string.write buf [%e arg]]
++  | [%type: bytes] ->
++    [%expr Deriving_Json.Json_bytes.write buf [%e arg]]
++  | [%type: [%t? y] list] ->
++    let e = write_of_type y ~poly in
++    [%expr Deriving_Json.write_list [%e e] buf [%e arg]]
++  | [%type: [%t? y] ref] ->
++    let e = write_of_type y ~poly in
++    [%expr Deriving_Json.write_ref [%e e] buf [%e arg]]
++  | [%type: [%t? y] option] ->
++    let e = write_of_type y ~poly in
++    [%expr Deriving_Json.write_option [%e e] buf [%e arg]]
++  | [%type: [%t? y] array] ->
++    let e = write_of_type y ~poly in
++    [%expr Deriving_Json.write_array [%e e] buf [%e arg]]
++  | { Parsetree.ptyp_desc = Ptyp_var v } when poly ->
++    [%expr [%e Ast_convenience.evar ("poly_" ^ v)] buf [%e arg]]
++  | { Parsetree.ptyp_desc = Ptyp_tuple l } ->
++    write_body_of_tuple_type l ~arg ~poly ~tag:0
++  | { Parsetree.ptyp_desc = Ptyp_variant (l, _, _); ptyp_loc = loc } ->
++    List.map (write_poly_case ~arg ~poly) l @ [unreachable_case ()] |>
++    Ast_helper.Exp.match_ arg
++  | { Parsetree.ptyp_desc = Ptyp_constr (lid, l) } ->
++    let e = suffix_lid lid ~suffix:"to_json"
++    and l = List.map (write_of_type ~poly) l in
++    [%expr [%e Ast_convenience.app e l] buf [%e arg]]
++  | { Parsetree.ptyp_loc } ->
++    Location.raise_errorf ~loc:ptyp_loc
++      "%s_write cannot be derived for %s"
++      deriver (Ppx_deriving.string_of_core_type y)
++
++and write_of_type y ~poly =
++  let v = "a" in
++  let arg = Ast_convenience.evar v
++  and pattern = Ast_convenience.pvar v in
++  wrap_write (write_body_of_type y ~arg ~poly) ~pattern
++
++and write_of_record ?(tag=0) d l =
++  let pattern =
++    let l =
++      let f {Parsetree.pld_name} =
++        label_of_constructor pld_name,
++        Ast_helper.Pat.var pld_name
++      in
++      List.map f l
++    in
++    Ast_helper.Pat.record l Asttypes.Closed
++  and e =
++    let l =
++      let f {Parsetree.pld_name = {txt}} = txt in
++      List.map f l
++    and ly =
++      let f {Parsetree.pld_type} = pld_type in
++      List.map f l
++    in
++    write_tuple_contents l ly ~tag ~poly:true
++  in
++  wrap_write e ~pattern
++
++let recognize_case_of_constructor i l =
++  let lhs =
++    match l with
++    | [] -> [%pat? `Cst  [%p Ast_convenience.pint i]]
++    | _  -> [%pat? `NCst [%p Ast_convenience.pint i]]
++  in
++  Ast_helper.Exp.case lhs [%expr true]
++
++let recognize_body_of_poly_variant l ~loc =
++  let l =
++    let f = function
++      | Parsetree.Rtag (label, _, _, l) ->
++        let i = Ppx_deriving.hash_variant label in
++        recognize_case_of_constructor i l
++      | Rinherit {ptyp_desc = Ptyp_constr (lid, _)} ->
++        let guard = [%expr [%e suffix_lid lid ~suffix:"recognize"] x] in
++        Ast_helper.Exp.case ~guard [%pat? x] [%expr true]
++      | _ ->
++        Location.raise_errorf ~loc
++          "%s_recognize cannot be derived" deriver
++    and default = Ast_helper.Exp.case [%pat? _] [%expr false] in
++    List.map f l @ [default]
++  in
++  Ast_helper.Exp.function_ l
++
++let tag_error_case ?(typename="") () =
++  let y = Ast_convenience.str typename in
++  Ast_helper.Exp.case
++    [%pat? _]
++    [%expr Deriving_Json_lexer.tag_error ~typename:[%e y] buf]
++
++let maybe_tuple_type = function
++  | [y] -> y
++  | l -> Ast_helper.Typ.tuple l
++
++let rec read_poly_case ?decl y = function
++  | Parsetree.Rtag (label, _, _, l) ->
++    let i = Ppx_deriving.hash_variant label |> Ast_convenience.pint in
++    (match l with
++     | [] ->
++       Ast_helper.Exp.case [%pat? `Cst [%p i]]
++         (Ast_helper.Exp.variant label None)
++     | l ->
++       Ast_helper.Exp.case [%pat? `NCst [%p i]] [%expr
++         Deriving_Json_lexer.read_comma buf;
++         let v = [%e read_body_of_type ?decl (maybe_tuple_type l)] in
++         Deriving_Json_lexer.read_rbracket buf;
++         [%e Ast_helper.Exp.variant label (Some [%expr v])]])
++  | Rinherit {ptyp_desc = Ptyp_constr (lid, l)} ->
++    let guard = [%expr [%e suffix_lid lid ~suffix:"recognize"] x]
++    and e =
++      let e = suffix_lid lid ~suffix:"of_json_with_tag"
++      and l = List.map (read_of_type ?decl) l in
++      [%expr ([%e Ast_convenience.app e l] buf x :> [%t y])]
++    in
++    Ast_helper.Exp.case ~guard [%pat? x] e
++  | Rinherit {ptyp_loc} ->
++    Location.raise_errorf ~loc:ptyp_loc
++      "%s read case cannot be derived" deriver
++
++and read_of_poly_variant ?decl l y ~loc =
++  List.map (read_poly_case ?decl y) l @ [tag_error_case ()] |>
++  Ast_helper.Exp.function_ |>
++  buf_expand
++
++and read_tuple_contents ?decl l ~f =
++  let n = List.length l in
++  let lv = fresh_vars n in
++  let f v y acc =
++    let e = read_body_of_type ?decl y in [%expr
++      Deriving_Json_lexer.read_comma buf;
++      let [%p Ast_convenience.pvar v] = [%e e] in
++      [%e acc]]
++  and acc = List.map Ast_convenience.evar lv |> f in
++  let acc = [%expr Deriving_Json_lexer.read_rbracket buf; [%e acc]] in
++  List.fold_right2 f lv l acc
++
++and read_body_of_tuple_type ?decl l = [%expr
++  Deriving_Json_lexer.read_lbracket buf;
++  ignore (Deriving_Json_lexer.read_tag_1 0 buf);
++  [%e read_tuple_contents ?decl l ~f:Ast_helper.Exp.tuple]]
++
++and read_of_record_raw ?decl l =
++  let f =
++    let f {Parsetree.pld_name} e = label_of_constructor pld_name, e in
++    fun l' -> Ast_helper.Exp.record (List.map2 f l l') None
++  and l =
++    let f {Parsetree.pld_type} = pld_type in
++    List.map f l
++  in
++  read_tuple_contents l ?decl ~f
++
++and read_of_record decl l =
++  let e = read_of_record_raw ~decl l in
++  [%expr
++      Deriving_Json_lexer.read_lbracket buf;
++      ignore (Deriving_Json_lexer.read_tag_2 0 254 buf);
++      [%e e]] |> buf_expand
++
++and read_body_of_type ?decl y =
++  let poly = match decl with Some _ -> true | _ -> false in
++  match y with
++  | [%type: unit] ->
++    [%expr Deriving_Json.Json_unit.read buf]
++  | [%type: int] ->
++    [%expr Deriving_Json.Json_int.read buf]
++  | [%type: int32] | [%type: Int32.t] ->
++    [%expr Deriving_Json.Json_int32.read buf]
++  | [%type: int64] | [%type: Int64.t] ->
++    [%expr Deriving_Json.Json_int64.read buf]
++  | [%type: nativeint] | [%type: Nativeint.t] ->
++    [%expr Deriving_Json.Json_nativeint.read buf]
++  | [%type: float] ->
++    [%expr Deriving_Json.Json_float.read buf]
++  | [%type: bool] ->
++    [%expr Deriving_Json.Json_bool.read buf]
++  | [%type: char] ->
++    [%expr Deriving_Json.Json_char.read buf]
++  | [%type: string] ->
++    [%expr Deriving_Json.Json_string.read buf]
++  | [%type: bytes] ->
++    [%expr Deriving_Json.Json_bytes.read buf]
++  | [%type: [%t? y] list] ->
++    [%expr Deriving_Json.read_list [%e read_of_type ?decl y] buf]
++  | [%type: [%t? y] ref] ->
++    [%expr Deriving_Json.read_ref [%e read_of_type ?decl y] buf]
++  | [%type: [%t? y] option] ->
++    [%expr Deriving_Json.read_option [%e read_of_type ?decl y] buf]
++  | [%type: [%t? y] array] ->
++    [%expr Deriving_Json.read_array [%e read_of_type ?decl y] buf]
++  | { Parsetree.ptyp_desc = Ptyp_tuple l } ->
++    read_body_of_tuple_type l ?decl
++  | { Parsetree.ptyp_desc = Ptyp_variant (l, _, _); ptyp_loc = loc } ->
++    let e =
++      (match decl with
++       | Some decl ->
++         let e = suffix_decl decl ~suffix:"of_json_with_tag"
++         and l =
++           let {Parsetree.ptype_params = l} = decl
++           and f (y, _) = read_of_type y ~decl in
++           List.map f l
++         in
++         Ast_convenience.app e l
++       | None ->
++         read_of_poly_variant l y ~loc)
++    and tag = [%expr Deriving_Json_lexer.read_vcase buf] in
++    [%expr [%e e] buf [%e tag]]
++  | { Parsetree.ptyp_desc = Ptyp_var v } when poly ->
++    [%expr [%e Ast_convenience.evar ("poly_" ^ v)] buf]
++  | { Parsetree.ptyp_desc = Ptyp_constr (lid, l) } ->
++    let e = suffix_lid lid ~suffix:"of_json"
++    and l = List.map (read_of_type ?decl) l in
++    [%expr [%e Ast_convenience.app e l] buf]
++  | { Parsetree.ptyp_loc } ->
++    Location.raise_errorf ~loc:ptyp_loc
++      "%s_read cannot be derived for %s" deriver
++      (Ppx_deriving.string_of_core_type y)
++
++and read_of_type ?decl y =
++  read_body_of_type ?decl y |> buf_expand
++
++let json_of_type ?decl y =
++  let read = read_of_type ?decl y
++  and write =
++    let poly = match decl with Some _ -> true | _ -> false in
++    write_of_type y ~poly in
++  [%expr Deriving_Json.make [%e write] [%e read]]
++
++let fun_str_wrap d e y ~f ~suffix =
++  let e = Ppx_deriving.poly_fun_of_type_decl d e |> sanitize
++  and v = suffix_decl_p d ~suffix
++  and y = Ppx_deriving.poly_arrow_of_type_decl f d y in
++  Ast_helper.(Vb.mk (Pat.constraint_ v y) e)
++
++let read_str_wrap d e =
++  let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]]
++  and suffix = "of_json" in
++  let y = f (Ppx_deriving.core_type_of_type_decl d) in
++  fun_str_wrap d e y ~f ~suffix
++
++let read_tag_str_wrap d e =
++  let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]]
++  and suffix = "of_json_with_tag"
++  and y =
++    let y = Ppx_deriving.core_type_of_type_decl d in
++    [%type: Deriving_Json_lexer.lexbuf ->
++          [`NCst of int | `Cst of int] -> [%t y]]
++  in
++  fun_str_wrap d e y ~f ~suffix
++
++let write_str_wrap d e =
++  let f y = [%type: Buffer.t -> [%t y] -> unit]
++  and suffix = "to_json" in
++  let y =
++    let y = Ppx_deriving.core_type_of_type_decl d in
++    (match d with
++     | {ptype_manifest =
++          Some {ptyp_desc = Parsetree.Ptyp_variant (_, _, _)}} ->
++       [%type: [> [%t y]]]
++     | _ ->
++       y) |> f
++  in
++  fun_str_wrap d e y ~f ~suffix
++
++let recognize_str_wrap d e =
++  let v = suffix_decl_p d ~suffix:"recognize"
++  and y = [%type: [`NCst of int | `Cst of int] -> bool] in
++  Ast_helper.(Vb.mk (Pat.constraint_ v y) e)
++
++let json_poly_type d =
++  let f y = [%type: [%t y] Deriving_Json.t] in
++  let y = f (Ppx_deriving.core_type_of_type_decl d) in
++  Ppx_deriving.poly_arrow_of_type_decl f d y
++
++let json_str_wrap d e =
++  let v = suffix_decl_p d ~suffix:"json"
++  and e = Ppx_deriving.(poly_fun_of_type_decl d e)
++  and y = json_poly_type d in
++  Ast_helper.(Vb.mk (Pat.constraint_ v y) e)
++
++let json_str d =
++  let write =
++    let f acc id =
++      let poly = Ast_convenience.evar ("poly_" ^ id) in
++      [%expr [%e acc] (Deriving_Json.write [%e poly])]
++    and acc = suffix_decl d ~suffix:"to_json" in
++    Ppx_deriving.fold_left_type_decl f acc d
++  and read =
++    let f acc id =
++      let poly = Ast_convenience.evar ("poly_" ^ id) in
++      [%expr [%e acc] (Deriving_Json.read [%e poly])]
++    and acc = suffix_decl d ~suffix:"of_json" in
++    Ppx_deriving.fold_left_type_decl f acc d
++  in
++  [%expr Deriving_Json.make [%e write] [%e read]] |>
++  json_str_wrap d
++
++let write_decl_of_type d y =
++  (let e =
++     let arg = Ast_convenience.evar "a" in
++     write_body_of_type y ~arg ~poly:true
++   in
++   [%expr fun buf a -> [%e e]]) |> write_str_wrap d
++
++let read_decl_of_type decl y =
++  read_body_of_type y ~decl |> buf_expand |> read_str_wrap decl
++
++let json_decls_of_type decl y =
++  let recognize, read_tag =
++    match y with
++    | { Parsetree.ptyp_desc = Ptyp_variant (l, _, _);
++        ptyp_loc = loc } ->
++      Some (recognize_body_of_poly_variant l ~loc
++            |> recognize_str_wrap decl),
++      Some (read_of_poly_variant l y ~decl ~loc
++            |> read_tag_str_wrap decl)
++    | _ ->
++      None, None
++  in
++  write_decl_of_type decl y,
++  read_decl_of_type decl y,
++  json_str decl,
++  recognize, read_tag
++
++let write_case (i, i', l) {Parsetree.pcd_name; pcd_args; pcd_loc} =
++  let i, i', lhs, rhs =
++    match pcd_args with
++#if OCAML_VERSION >= (4, 03, 0)
++    | Pcstr_tuple [] | Pcstr_record [] ->
++#else
++    | [] ->
++#endif
++      i + 1,
++      i',
++      None,
++      [%expr Deriving_Json.Json_int.write buf
++               [%e Ast_convenience.int i]]
++#if OCAML_VERSION >= (4, 03, 0)
++    | Pcstr_tuple ([ _ ] as args) ->
++#else
++    | [ _ ] as args ->
++#endif
++      let v = Ppx_deriving.fresh_var [] in
++      i,
++      i' + 1,
++      Some (Ast_convenience.pvar v),
++      write_tuple_contents [v] args ~tag:i' ~poly:true
++#if OCAML_VERSION >= (4, 03, 0)
++    | Pcstr_tuple args ->
++#else
++    | args ->
++#endif
++      let vars = fresh_vars (List.length args) in
++      i,
++      i' + 1,
++      Some (var_ptuple vars),
++      write_tuple_contents vars args ~tag:i' ~poly:true
++#if OCAML_VERSION >= (4, 03, 0)
++    | Pcstr_record args ->
++      let vars = fresh_vars (List.length args) in
++      i,
++      i' + 1,
++      Some (var_ptuple vars),
++      write_of_record vars args ~tag:i'
++#endif
++  in
++  i, i',
++  Ast_helper.
++    (Exp.case (Pat.construct (label_of_constructor pcd_name) lhs)
++       rhs) :: l
++
++let write_decl_of_variant d l =
++  (let _, _, l = List.fold_left write_case (0, 0, []) l in
++   Ast_helper.Exp.function_ l) |> buf_expand |>
++  write_str_wrap d
++
++let read_case ?decl (i, i', l)
++    {Parsetree.pcd_name; pcd_args; pcd_loc} =
++  match pcd_args with
++#if OCAML_VERSION >= (4, 03, 0)
++  | Pcstr_tuple [] | Pcstr_record [] ->
++#else
++  | [] ->
++#endif
++    i + 1, i',
++    Ast_helper.Exp.case
++      [%pat? `Cst [%p Ast_convenience.pint i]]
++      (Ast_helper.Exp.construct (label_of_constructor pcd_name) None)
++    :: l
++#if OCAML_VERSION >= (4, 03, 0)
++  | Pcstr_tuple pcd_args ->
++#else
++  | pcd_args ->
++#endif
++     let f l =
++       let args =
++         match l with
++         | [] ->  None
++         | [e] -> Some e
++         | l ->   Some (Ast_helper.Exp.tuple l)
++       in Ast_helper.Exp.construct (label_of_constructor pcd_name) args
++     in
++     let expr = read_tuple_contents ?decl pcd_args ~f in
++     let case = Ast_helper.Exp.case [%pat? `NCst [%p Ast_convenience.pint i']] expr in
++     i, i' + 1, case :: l
++#if OCAML_VERSION >= (4, 03, 0)
++  | Pcstr_record pcd_args ->
++     let expr = read_of_record_raw ?decl pcd_args in
++     let case = Ast_helper.Exp.case [%pat? `NCst [%p Ast_convenience.pint i']] expr in
++     i, i' + 1, case :: l
++#endif
++
++let read_decl_of_variant decl l =
++  (let _, _, l = List.fold_left (read_case ~decl) (0, 0, []) l
++   and e = [%expr Deriving_Json_lexer.read_case buf] in
++   Ast_helper.Exp.match_ e (l @ [tag_error_case ()])) |>
++  buf_expand |>
++  read_str_wrap decl
++
++let json_decls_of_variant d l =
++  write_decl_of_variant d l, read_decl_of_variant d l, json_str d,
++  None, None
++
++let write_decl_of_record d l =
++  write_of_record d l |> write_str_wrap d
++
++let read_decl_of_record d l =
++  read_of_record d l |> read_str_wrap d
++
++let json_decls_of_record d l =
++  check_record_fields l;
++  write_decl_of_record d l, read_decl_of_record d l, json_str d,
++  None, None
++
++let json_str_of_decl ({Parsetree.ptype_loc} as d) =
++  Ast_helper.with_default_loc ptype_loc @@ fun () ->
++  match d with
++  | { Parsetree.ptype_manifest = Some y } ->
++    json_decls_of_type d y
++  | { ptype_kind = Ptype_variant l } ->
++    json_decls_of_variant d l
++  | { ptype_kind = Ptype_record l } ->
++    json_decls_of_record d l
++  | _ ->
++    Location.raise_errorf "%s cannot be derived for %s" deriver
++      (Ppx_deriving.mangle_type_decl (`Suffix "") d)
++
++let read_sig_of_decl ({Parsetree.ptype_loc} as d) =
++  (let s =
++     let s = Ppx_deriving.mangle_type_decl (`Suffix "of_json") d in
++     Location.mkloc s ptype_loc
++   and y =
++     let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]] in
++     let y = f (Ppx_deriving.core_type_of_type_decl d) in
++     Ppx_deriving.poly_arrow_of_type_decl f d y
++   in
++   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
++
++let recognize_sig_of_decl ({Parsetree.ptype_loc} as d) =
++  (let s =
++     let s = Ppx_deriving.mangle_type_decl (`Suffix "recognize") d in
++     Location.mkloc s ptype_loc
++   and y = [%type: [ `NCst of int  | `Cst of int ] -> bool] in
++   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
++
++let read_with_tag_sig_of_decl ({Parsetree.ptype_loc} as d) =
++  (let s =
++     let s =
++       Ppx_deriving.mangle_type_decl (`Suffix "of_json_with_tag") d
++     in
++     Location.mkloc s ptype_loc
++   and y =
++     let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]] in
++     let y =
++       let y = Ppx_deriving.core_type_of_type_decl d in
++       f [%type: [ `NCst of int  | `Cst of int ] -> [%t y]]
++     in
++     Ppx_deriving.poly_arrow_of_type_decl f d y
++   in
++   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
++
++let write_sig_of_decl ({Parsetree.ptype_loc} as d) =
++  (let s =
++     let s = Ppx_deriving.mangle_type_decl (`Suffix "to_json") d in
++     Location.mkloc s ptype_loc
++   and y =
++     let f y = [%type: Buffer.t -> [%t y] -> unit] in
++     let y = f (Ppx_deriving.core_type_of_type_decl d) in
++     Ppx_deriving.poly_arrow_of_type_decl f d y
++   in
++   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
++
++let json_sig_of_decl ({Parsetree.ptype_loc} as d) =
++  (let s =
++     let s = Ppx_deriving.mangle_type_decl (`Suffix "json") d in
++     Location.mkloc s ptype_loc
++   and y =
++     let f y = [%type: [%t y] Deriving_Json.t] in
++     let y = f (Ppx_deriving.core_type_of_type_decl d) in
++     Ppx_deriving.poly_arrow_of_type_decl f d y
++   in
++   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
++
++let sigs_of_decl ({Parsetree.ptype_loc} as d) =
++  Ast_helper.with_default_loc ptype_loc @@ fun () ->
++  let l = [
++    read_sig_of_decl d;
++    write_sig_of_decl d;
++    json_sig_of_decl d
++  ] in
++  match d with
++  | { Parsetree.ptype_manifest =
++        Some {Parsetree.ptyp_desc = Parsetree.Ptyp_variant _}} ->
++    read_with_tag_sig_of_decl d :: recognize_sig_of_decl d :: l
++  | _ ->
++    l
++
++let register_for_expr s f =
++  let core_type ({Parsetree.ptyp_loc} as y) =
++    let f () = f y |> sanitize in
++    Ast_helper.with_default_loc ptyp_loc f
++  in
++  Ppx_deriving.(create s ~core_type () |> register)
++
++let _ =
++  register_for_expr "of_json" @@ fun y -> [%expr
++    fun s ->
++      [%e read_of_type y]
++        (Deriving_Json_lexer.init_lexer (Lexing.from_string s))]
++
++let _ =
++  register_for_expr "to_json" @@ fun y -> [%expr
++    fun x ->
++      let buf = Buffer.create 50 in
++      [%e write_of_type y ~poly:false] buf x;
++      Buffer.contents buf]
++
++let _ =
++  let core_type ({Parsetree.ptyp_loc} as y) =
++    let f () = json_of_type y |> sanitize in
++    Ast_helper.with_default_loc ptyp_loc f
++  and type_decl_str ~options ~path l =
++    let lw, lr, lj, lp, lrv =
++      let f d (lw, lr, lj, lp, lrv) =
++        let w, r, j, p, rv = json_str_of_decl d in
++        w :: lw, r :: lr, j :: lj,
++        (match p with Some p -> p :: lp | None -> lp),
++        (match rv with Some rv -> rv :: lrv | None -> lrv)
++      and acc = [], [], [], [], [] in
++      List.fold_right f l acc
++    and f = Ast_helper.Str.value Asttypes.Recursive
++    and f' = Ast_helper.Str.value Asttypes.Nonrecursive in
++    let l = [f (lrv @ lr); f lw; f' lj] in
++    match lp with [] -> l | _ -> f lp :: l
++  and type_decl_sig ~options ~path l =
++    List.map sigs_of_decl l |> List.flatten
++  in
++  Ppx_deriving.
++    (create "json" ~core_type ~type_decl_str ~type_decl_sig ()
++     |> register)
+diff --git a/lib/ppx/ppx_deriving_json.ml b/lib/ppx/ppx_deriving_json.ml
+deleted file mode 100644
+index e96ce3f..0000000
+--- a/lib/ppx/ppx_deriving_json.ml
++++ /dev/null
+@@ -1,675 +0,0 @@
+-(* Js_of_ocaml
+- * http://www.ocsigen.org
+- * Copyright Vasilis Papavasileiou 2015
+- *
+- * This program is free software; you can redistribute it and/or modify
+- * it under the terms of the GNU Lesser General Public License as published by
+- * the Free Software Foundation, with linking exception;
+- * either version 2.1 of the License, or (at your option) any later version.
+- *
+- * 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
+- * GNU Lesser General Public License for more details.
+- *
+- * You should have received a copy of the GNU Lesser General Public License
+- * along with this program; if not, write to the Free Software
+- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+- *)
+-
+-let deriver = "json"
+-
+-(* Copied (and adapted) this from ppx_deriving repo (commit
+-   e2079fa8f3460055bf990461f295c6c4b391fafc) ; we get an empty set of
+-   let bindings with ppx_deriving 3.0 *)
+-let sanitize expr = [%expr
+-  (let open! Ppx_deriving_runtime in [%e expr]) [@ocaml.warning "-A"]]
+-
+-let var_ptuple l =
+-  List.map Ast_convenience.pvar l |> Ast_helper.Pat.tuple
+-
+-let map_loc f {Location.txt; loc} =
+-  {Location.txt = f txt; loc}
+-
+-let suffix_lid {Location.txt; loc} ~suffix =
+-  let txt = Ppx_deriving.mangle_lid (`Suffix suffix) txt in
+-  Ast_helper.Exp.ident {txt; loc} ~loc
+-
+-let suffix_decl ({Parsetree.ptype_loc = loc} as d) ~suffix =
+-  (let s =
+-     Ppx_deriving.mangle_type_decl (`Suffix suffix) d |>
+-     Longident.parse
+-   in
+-   Location.mkloc s loc) |> Ast_helper.Exp.ident ~loc
+-
+-let suffix_decl_p ({Parsetree.ptype_loc = loc} as d) ~suffix =
+-  (let s = Ppx_deriving.mangle_type_decl (`Suffix suffix) d in
+-   Location.mkloc s loc) |> Ast_helper.Pat.var ~loc
+-
+-let rec fresh_vars ?(acc = []) n =
+-  if n <= 0 then
+-    List.rev acc
+-  else
+-    let acc = Ppx_deriving.fresh_var acc :: acc in
+-    fresh_vars ~acc (n - 1)
+-
+-let unreachable_case () =
+-  Ast_helper.Exp.case [%pat? _ ] [%expr assert false]
+-
+-let label_of_constructor = map_loc (fun c -> Longident.Lident c)
+-
+-let wrap_write r ~pattern = [%expr fun buf [%p pattern] -> [%e r]]
+-
+-let buf_expand r = [%expr fun buf -> [%e r]]
+-
+-let seqlist = function
+-  | h :: l ->
+-    let f acc e = [%expr [%e acc]; [%e e]] in
+-    List.fold_left f h l
+-  | [] ->
+-    [%expr ()]
+-
+-let check_record_fields =
+-  List.iter @@ function
+-  | {Parsetree.pld_mutable = Mutable} ->
+-    Location.raise_errorf
+-      "%s cannot be derived for mutable records" deriver
+-  | {pld_type = {ptyp_desc = Ptyp_poly _}} ->
+-    Location.raise_errorf
+-      "%s cannot be derived for polymorphic records" deriver
+-  | _ ->
+-    ()
+-
+-let maybe_tuple_type = function
+-  | [y] -> y
+-  | l -> Ast_helper.Typ.tuple l
+-
+-let rec write_tuple_contents l ly tag ~poly =
+-  let e =
+-    let f v y =
+-      let arg = Ast_convenience.evar v in
+-      let e = write_body_of_type y ~arg ~poly in
+-      [%expr Buffer.add_string buf ","; [%e e]]
+-    in
+-    List.map2 f l ly |> seqlist
+-  and s = Ast_convenience.str ("[" ^ string_of_int tag) in [%expr
+-    Buffer.add_string buf [%e s];
+-    [%e e];
+-    Buffer.add_string buf "]"]
+-
+-and write_body_of_tuple_type l ~arg ~poly ~tag =
+-  let n = List.length l in
+-  let vars = fresh_vars n in
+-  let e = write_tuple_contents vars l tag ~poly
+-  and p = var_ptuple vars in
+-  [%expr let [%p p] = [%e arg] in [%e e]]
+-
+-and write_poly_case r ~arg ~poly =
+-  match r with
+-  | Parsetree.Rtag (label, _, _, l) ->
+-    let i = Ppx_deriving.hash_variant label
+-    and n = List.length l in
+-    let v = Ppx_deriving.fresh_var [] in
+-    let lhs =
+-      (if n = 0 then None else Some (Ast_convenience.pvar v)) |>
+-      Ast_helper.Pat.variant label
+-    and rhs =
+-      match l with
+-      | [] ->
+-        let e = Ast_convenience.int i in
+-        [%expr Deriving_Json.Json_int.write buf [%e e]]
+-      | _ ->
+-        let l = [[%type: int]; maybe_tuple_type l]
+-        and arg = Ast_helper.Exp.tuple Ast_convenience.[int i; evar v] in
+-        write_body_of_tuple_type l ~arg ~poly ~tag:0
+-    in
+-    Ast_helper.Exp.case lhs rhs
+-  | Rinherit ({ptyp_desc = Ptyp_constr (lid, _)} as y) ->
+-    Ast_helper.Exp.case (Ast_helper.Pat.type_ lid)
+-      (write_body_of_type y ~arg ~poly)
+-  | Rinherit {ptyp_loc} ->
+-    Location.raise_errorf ~loc:ptyp_loc
+-      "%s write case cannot be derived" deriver
+-
+-and write_body_of_type y ~arg ~poly =
+-  match y with
+-  | [%type: unit] ->
+-    [%expr Deriving_Json.Json_unit.write buf [%e arg]]
+-  | [%type: int] ->
+-    [%expr Deriving_Json.Json_int.write buf [%e arg]]
+-  | [%type: int32] | [%type: Int32.t] ->
+-    [%expr Deriving_Json.Json_int32.write buf [%e arg]]
+-  | [%type: int64] | [%type: Int64.t] ->
+-    [%expr Deriving_Json.Json_int64.write buf [%e arg]]
+-  | [%type: nativeint] | [%type: Nativeint.t] ->
+-    [%expr Deriving_Json.Json_nativeint.write buf [%e arg]]
+-  | [%type: float] ->
+-    [%expr Deriving_Json.Json_float.write buf [%e arg]]
+-  | [%type: bool] ->
+-    [%expr Deriving_Json.Json_bool.write buf [%e arg]]
+-  | [%type: char] ->
+-    [%expr Deriving_Json.Json_char.write buf [%e arg]]
+-  | [%type: string] ->
+-    [%expr Deriving_Json.Json_string.write buf [%e arg]]
+-  | [%type: bytes] ->
+-    [%expr Deriving_Json.Json_bytes.write buf [%e arg]]
+-  | [%type: [%t? y] list] ->
+-    let e = write_of_type y ~poly in
+-    [%expr Deriving_Json.write_list [%e e] buf [%e arg]]
+-  | [%type: [%t? y] ref] ->
+-    let e = write_of_type y ~poly in
+-    [%expr Deriving_Json.write_ref [%e e] buf [%e arg]]
+-  | [%type: [%t? y] option] ->
+-    let e = write_of_type y ~poly in
+-    [%expr Deriving_Json.write_option [%e e] buf [%e arg]]
+-  | [%type: [%t? y] array] ->
+-    let e = write_of_type y ~poly in
+-    [%expr Deriving_Json.write_array [%e e] buf [%e arg]]
+-  | { Parsetree.ptyp_desc = Ptyp_var v } when poly ->
+-    [%expr [%e Ast_convenience.evar ("poly_" ^ v)] buf [%e arg]]
+-  | { Parsetree.ptyp_desc = Ptyp_tuple l } ->
+-    write_body_of_tuple_type l ~arg ~poly ~tag:0
+-  | { Parsetree.ptyp_desc = Ptyp_variant (l, _, _); ptyp_loc = loc } ->
+-    List.map (write_poly_case ~arg ~poly) l @ [unreachable_case ()] |>
+-    Ast_helper.Exp.match_ arg
+-  | { Parsetree.ptyp_desc = Ptyp_constr (lid, l) } ->
+-    let e = suffix_lid lid ~suffix:"to_json"
+-    and l = List.map (write_of_type ~poly) l in
+-    [%expr [%e Ast_convenience.app e l] buf [%e arg]]
+-  | { Parsetree.ptyp_loc } ->
+-    Location.raise_errorf ~loc:ptyp_loc
+-      "%s_write cannot be derived for %s"
+-      deriver (Ppx_deriving.string_of_core_type y)
+-
+-and write_of_type y ~poly =
+-  let v = "a" in
+-  let arg = Ast_convenience.evar v
+-  and pattern = Ast_convenience.pvar v in
+-  wrap_write (write_body_of_type y ~arg ~poly) ~pattern
+-
+-and write_of_record d l =
+-  let pattern =
+-    let l =
+-      let f {Parsetree.pld_name} =
+-        label_of_constructor pld_name,
+-        Ast_helper.Pat.var pld_name
+-      in
+-      List.map f l
+-    in
+-    Ast_helper.Pat.record l Asttypes.Closed
+-  and e =
+-    let l =
+-      let f {Parsetree.pld_name = {txt}} = txt in
+-      List.map f l
+-    and ly =
+-      let f {Parsetree.pld_type} = pld_type in
+-      List.map f l
+-    in
+-    write_tuple_contents l ly 0 ~poly:true
+-  in
+-  wrap_write e ~pattern
+-
+-let recognize_case_of_constructor i l =
+-  let lhs =
+-    match l with
+-    | [] -> [%pat? `Cst  [%p Ast_convenience.pint i]]
+-    | _  -> [%pat? `NCst [%p Ast_convenience.pint i]]
+-  in
+-  Ast_helper.Exp.case lhs [%expr true]
+-
+-let recognize_body_of_poly_variant l ~loc =
+-  let l =
+-    let f = function
+-      | Parsetree.Rtag (label, _, _, l) ->
+-        let i = Ppx_deriving.hash_variant label in
+-        recognize_case_of_constructor i l
+-      | Rinherit {ptyp_desc = Ptyp_constr (lid, _)} ->
+-        let guard = [%expr [%e suffix_lid lid ~suffix:"recognize"] x] in
+-        Ast_helper.Exp.case ~guard [%pat? x] [%expr true]
+-      | _ ->
+-        Location.raise_errorf ~loc
+-          "%s_recognize cannot be derived" deriver
+-    and default = Ast_helper.Exp.case [%pat? _] [%expr false] in
+-    List.map f l @ [default]
+-  in
+-  Ast_helper.Exp.function_ l
+-
+-let tag_error_case ?(typename="") () =
+-  let y = Ast_convenience.str typename in
+-  Ast_helper.Exp.case
+-    [%pat? _]
+-    [%expr Deriving_Json_lexer.tag_error ~typename:[%e y] buf]
+-
+-let maybe_tuple_type = function
+-  | [y] -> y
+-  | l -> Ast_helper.Typ.tuple l
+-
+-let rec read_poly_case ?decl y = function
+-  | Parsetree.Rtag (label, _, _, l) ->
+-    let i = Ppx_deriving.hash_variant label |> Ast_convenience.pint in
+-    (match l with
+-     | [] ->
+-       Ast_helper.Exp.case [%pat? `Cst [%p i]]
+-         (Ast_helper.Exp.variant label None)
+-     | l ->
+-       Ast_helper.Exp.case [%pat? `NCst [%p i]] [%expr
+-         Deriving_Json_lexer.read_comma buf;
+-         let v = [%e read_body_of_type ?decl (maybe_tuple_type l)] in
+-         Deriving_Json_lexer.read_rbracket buf;
+-         [%e Ast_helper.Exp.variant label (Some [%expr v])]])
+-  | Rinherit {ptyp_desc = Ptyp_constr (lid, l)} ->
+-    let guard = [%expr [%e suffix_lid lid ~suffix:"recognize"] x]
+-    and e =
+-      let e = suffix_lid lid ~suffix:"of_json_with_tag"
+-      and l = List.map (read_of_type ?decl) l in
+-      [%expr ([%e Ast_convenience.app e l] buf x :> [%t y])]
+-    in
+-    Ast_helper.Exp.case ~guard [%pat? x] e
+-  | Rinherit {ptyp_loc} ->
+-    Location.raise_errorf ~loc:ptyp_loc
+-      "%s read case cannot be derived" deriver
+-
+-and read_of_poly_variant ?decl l y ~loc =
+-  List.map (read_poly_case ?decl y) l @ [tag_error_case ()] |>
+-  Ast_helper.Exp.function_ |>
+-  buf_expand
+-
+-and read_tuple_contents ?decl l ~f =
+-  let n = List.length l in
+-  let lv = fresh_vars n in
+-  let f v y acc =
+-    let e = read_body_of_type ?decl y in [%expr
+-      Deriving_Json_lexer.read_comma buf;
+-      let [%p Ast_convenience.pvar v] = [%e e] in
+-      [%e acc]]
+-  and acc = List.map Ast_convenience.evar lv |> f in
+-  let acc = [%expr Deriving_Json_lexer.read_rbracket buf; [%e acc]] in
+-  List.fold_right2 f lv l acc
+-
+-and read_body_of_tuple_type ?decl l = [%expr
+-  Deriving_Json_lexer.read_lbracket buf;
+-  ignore (Deriving_Json_lexer.read_tag_1 0 buf);
+-  [%e read_tuple_contents ?decl l ~f:Ast_helper.Exp.tuple]]
+-
+-and read_of_record decl l =
+-  let e =
+-    let f =
+-      let f {Parsetree.pld_name} e = label_of_constructor pld_name, e in
+-      fun l' -> Ast_helper.Exp.record (List.map2 f l l') None
+-    and l =
+-      let f {Parsetree.pld_type} = pld_type in
+-      List.map f l
+-    in
+-    read_tuple_contents l ~decl ~f
+-  in [%expr
+-    Deriving_Json_lexer.read_lbracket buf;
+-    ignore (Deriving_Json_lexer.read_tag_2 0 254 buf);
+-    [%e e]] |> buf_expand
+-
+-and read_body_of_type ?decl y =
+-  let poly = match decl with Some _ -> true | _ -> false in
+-  match y with
+-  | [%type: unit] ->
+-    [%expr Deriving_Json.Json_unit.read buf]
+-  | [%type: int] ->
+-    [%expr Deriving_Json.Json_int.read buf]
+-  | [%type: int32] | [%type: Int32.t] ->
+-    [%expr Deriving_Json.Json_int32.read buf]
+-  | [%type: int64] | [%type: Int64.t] ->
+-    [%expr Deriving_Json.Json_int64.read buf]
+-  | [%type: nativeint] | [%type: Nativeint.t] ->
+-    [%expr Deriving_Json.Json_nativeint.read buf]
+-  | [%type: float] ->
+-    [%expr Deriving_Json.Json_float.read buf]
+-  | [%type: bool] ->
+-    [%expr Deriving_Json.Json_bool.read buf]
+-  | [%type: char] ->
+-    [%expr Deriving_Json.Json_char.read buf]
+-  | [%type: string] ->
+-    [%expr Deriving_Json.Json_string.read buf]
+-  | [%type: bytes] ->
+-    [%expr Deriving_Json.Json_bytes.read buf]
+-  | [%type: [%t? y] list] ->
+-    [%expr Deriving_Json.read_list [%e read_of_type ?decl y] buf]
+-  | [%type: [%t? y] ref] ->
+-    [%expr Deriving_Json.read_ref [%e read_of_type ?decl y] buf]
+-  | [%type: [%t? y] option] ->
+-    [%expr Deriving_Json.read_option [%e read_of_type ?decl y] buf]
+-  | [%type: [%t? y] array] ->
+-    [%expr Deriving_Json.read_array [%e read_of_type ?decl y] buf]
+-  | { Parsetree.ptyp_desc = Ptyp_tuple l } ->
+-    read_body_of_tuple_type l ?decl
+-  | { Parsetree.ptyp_desc = Ptyp_variant (l, _, _); ptyp_loc = loc } ->
+-    let e =
+-      (match decl with
+-       | Some decl ->
+-         let e = suffix_decl decl ~suffix:"of_json_with_tag"
+-         and l =
+-           let {Parsetree.ptype_params = l} = decl
+-           and f (y, _) = read_of_type y ~decl in
+-           List.map f l
+-         in
+-         Ast_convenience.app e l
+-       | None ->
+-         read_of_poly_variant l y ~loc)
+-    and tag = [%expr Deriving_Json_lexer.read_vcase buf] in
+-    [%expr [%e e] buf [%e tag]]
+-  | { Parsetree.ptyp_desc = Ptyp_var v } when poly ->
+-    [%expr [%e Ast_convenience.evar ("poly_" ^ v)] buf]
+-  | { Parsetree.ptyp_desc = Ptyp_constr (lid, l) } ->
+-    let e = suffix_lid lid ~suffix:"of_json"
+-    and l = List.map (read_of_type ?decl) l in
+-    [%expr [%e Ast_convenience.app e l] buf]
+-  | { Parsetree.ptyp_loc } ->
+-    Location.raise_errorf ~loc:ptyp_loc
+-      "%s_read cannot be derived for %s" deriver
+-      (Ppx_deriving.string_of_core_type y)
+-
+-and read_of_type ?decl y =
+-  read_body_of_type ?decl y |> buf_expand
+-
+-let json_of_type ?decl y =
+-  let read = read_of_type ?decl y
+-  and write =
+-    let poly = match decl with Some _ -> true | _ -> false in
+-    write_of_type y ~poly in
+-  [%expr Deriving_Json.make [%e write] [%e read]]
+-
+-let fun_str_wrap d e y ~f ~suffix =
+-  let e = Ppx_deriving.poly_fun_of_type_decl d e |> sanitize
+-  and v = suffix_decl_p d ~suffix
+-  and y = Ppx_deriving.poly_arrow_of_type_decl f d y in
+-  Ast_helper.(Vb.mk (Pat.constraint_ v y) e)
+-
+-let read_str_wrap d e =
+-  let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]]
+-  and suffix = "of_json" in
+-  let y = f (Ppx_deriving.core_type_of_type_decl d) in
+-  fun_str_wrap d e y ~f ~suffix
+-
+-let read_tag_str_wrap d e =
+-  let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]]
+-  and suffix = "of_json_with_tag"
+-  and y =
+-    let y = Ppx_deriving.core_type_of_type_decl d in
+-    [%type: Deriving_Json_lexer.lexbuf ->
+-          [`NCst of int | `Cst of int] -> [%t y]]
+-  in
+-  fun_str_wrap d e y ~f ~suffix
+-
+-let write_str_wrap d e =
+-  let f y = [%type: Buffer.t -> [%t y] -> unit]
+-  and suffix = "to_json" in
+-  let y =
+-    let y = Ppx_deriving.core_type_of_type_decl d in
+-    (match d with
+-     | {ptype_manifest =
+-          Some {ptyp_desc = Parsetree.Ptyp_variant (_, _, _)}} ->
+-       [%type: [> [%t y]]]
+-     | _ ->
+-       y) |> f
+-  in
+-  fun_str_wrap d e y ~f ~suffix
+-
+-let recognize_str_wrap d e =
+-  let v = suffix_decl_p d ~suffix:"recognize"
+-  and y = [%type: [`NCst of int | `Cst of int] -> bool] in
+-  Ast_helper.(Vb.mk (Pat.constraint_ v y) e)
+-
+-let json_poly_type d =
+-  let f y = [%type: [%t y] Deriving_Json.t] in
+-  let y = f (Ppx_deriving.core_type_of_type_decl d) in
+-  Ppx_deriving.poly_arrow_of_type_decl f d y
+-
+-let json_str_wrap d e =
+-  let v = suffix_decl_p d ~suffix:"json"
+-  and e = Ppx_deriving.(poly_fun_of_type_decl d e)
+-  and y = json_poly_type d in
+-  Ast_helper.(Vb.mk (Pat.constraint_ v y) e)
+-
+-let json_str d =
+-  let write =
+-    let f acc id =
+-      let poly = Ast_convenience.evar ("poly_" ^ id) in
+-      [%expr [%e acc] (Deriving_Json.write [%e poly])]
+-    and acc = suffix_decl d ~suffix:"to_json" in
+-    Ppx_deriving.fold_left_type_decl f acc d
+-  and read =
+-    let f acc id =
+-      let poly = Ast_convenience.evar ("poly_" ^ id) in
+-      [%expr [%e acc] (Deriving_Json.read [%e poly])]
+-    and acc = suffix_decl d ~suffix:"of_json" in
+-    Ppx_deriving.fold_left_type_decl f acc d
+-  in
+-  [%expr Deriving_Json.make [%e write] [%e read]] |>
+-  json_str_wrap d
+-
+-let write_decl_of_type d y =
+-  (let e =
+-     let arg = Ast_convenience.evar "a" in
+-     write_body_of_type y ~arg ~poly:true
+-   in
+-   [%expr fun buf a -> [%e e]]) |> write_str_wrap d
+-
+-let read_decl_of_type decl y =
+-  read_body_of_type y ~decl |> buf_expand |> read_str_wrap decl
+-
+-let json_decls_of_type decl y =
+-  let recognize, read_tag =
+-    match y with
+-    | { Parsetree.ptyp_desc = Ptyp_variant (l, _, _);
+-        ptyp_loc = loc } ->
+-      Some (recognize_body_of_poly_variant l ~loc
+-            |> recognize_str_wrap decl),
+-      Some (read_of_poly_variant l y ~decl ~loc
+-            |> read_tag_str_wrap decl)
+-    | _ ->
+-      None, None
+-  in
+-  write_decl_of_type decl y,
+-  read_decl_of_type decl y,
+-  json_str decl,
+-  recognize, read_tag
+-
+-let write_case (i, i', l) {Parsetree.pcd_name; pcd_args; pcd_loc} =
+-  let n = List.length pcd_args in
+-  let vars = fresh_vars n in
+-  let i, i', lhs, rhs =
+-    match vars with
+-    | [] ->
+-      i + 1,
+-      i',
+-      None,
+-      [%expr Deriving_Json.Json_int.write buf
+-               [%e Ast_convenience.int i]]
+-    | [v] ->
+-      i,
+-      i' + 1,
+-      Some (Ast_convenience.pvar v),
+-      write_tuple_contents vars pcd_args i' ~poly:true
+-    | _ ->
+-      i,
+-      i' + 1,
+-      Some (var_ptuple vars),
+-      write_tuple_contents vars pcd_args i' ~poly:true
+-  in
+-  i, i',
+-  Ast_helper.
+-    (Exp.case (Pat.construct (label_of_constructor pcd_name) lhs)
+-       rhs) :: l
+-
+-let write_decl_of_variant d l =
+-  (let _, _, l = List.fold_left write_case (0, 0, []) l in
+-   Ast_helper.Exp.function_ l) |> buf_expand |>
+-  write_str_wrap d
+-
+-let read_case ?decl (i, i', l)
+-    {Parsetree.pcd_name; pcd_args; pcd_loc} =
+-  match pcd_args with
+-  | [] ->
+-    i + 1, i',
+-    Ast_helper.Exp.case
+-      [%pat? `Cst [%p Ast_convenience.pint i]]
+-      (Ast_helper.Exp.construct (label_of_constructor pcd_name) None)
+-    :: l
+-  | _ ->
+-    i, i' + 1,
+-    ((let f l =
+-        (match l with
+-         | [] ->  None
+-         | [e] -> Some e
+-         | l ->   Some (Ast_helper.Exp.tuple l)) |>
+-        Ast_helper.Exp.construct (label_of_constructor pcd_name)
+-      in
+-      read_tuple_contents ?decl pcd_args ~f) |>
+-     Ast_helper.Exp.case [%pat? `NCst [%p Ast_convenience.pint i']])
+-    :: l
+-
+-let read_decl_of_variant decl l =
+-  (let _, _, l = List.fold_left (read_case ~decl) (0, 0, []) l
+-   and e = [%expr Deriving_Json_lexer.read_case buf] in
+-   Ast_helper.Exp.match_ e (l @ [tag_error_case ()])) |>
+-  buf_expand |>
+-  read_str_wrap decl
+-
+-let json_decls_of_variant d l =
+-  write_decl_of_variant d l, read_decl_of_variant d l, json_str d,
+-  None, None
+-
+-let write_decl_of_record d l =
+-  write_of_record d l |> write_str_wrap d
+-
+-let read_decl_of_record d l =
+-  read_of_record d l |> read_str_wrap d
+-
+-let json_decls_of_record d l =
+-  check_record_fields l;
+-  write_decl_of_record d l, read_decl_of_record d l, json_str d,
+-  None, None
+-
+-let json_str_of_decl ({Parsetree.ptype_loc} as d) =
+-  Ast_helper.with_default_loc ptype_loc @@ fun () ->
+-  match d with
+-  | { Parsetree.ptype_manifest = Some y } ->
+-    json_decls_of_type d y
+-  | { ptype_kind = Ptype_variant l } ->
+-    json_decls_of_variant d l
+-  | { ptype_kind = Ptype_record l } ->
+-    json_decls_of_record d l
+-  | _ ->
+-    Location.raise_errorf "%s cannot be derived for %s" deriver
+-      (Ppx_deriving.mangle_type_decl (`Suffix "") d)
+-
+-let read_sig_of_decl ({Parsetree.ptype_loc} as d) =
+-  (let s =
+-     let s = Ppx_deriving.mangle_type_decl (`Suffix "of_json") d in
+-     Location.mkloc s ptype_loc
+-   and y =
+-     let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]] in
+-     let y = f (Ppx_deriving.core_type_of_type_decl d) in
+-     Ppx_deriving.poly_arrow_of_type_decl f d y
+-   in
+-   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
+-
+-let recognize_sig_of_decl ({Parsetree.ptype_loc} as d) =
+-  (let s =
+-     let s = Ppx_deriving.mangle_type_decl (`Suffix "recognize") d in
+-     Location.mkloc s ptype_loc
+-   and y = [%type: [ `NCst of int  | `Cst of int ] -> bool] in
+-   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
+-
+-let read_with_tag_sig_of_decl ({Parsetree.ptype_loc} as d) =
+-  (let s =
+-     let s =
+-       Ppx_deriving.mangle_type_decl (`Suffix "of_json_with_tag") d
+-     in
+-     Location.mkloc s ptype_loc
+-   and y =
+-     let f y = [%type: Deriving_Json_lexer.lexbuf -> [%t y]] in
+-     let y =
+-       let y = Ppx_deriving.core_type_of_type_decl d in
+-       f [%type: [ `NCst of int  | `Cst of int ] -> [%t y]]
+-     in
+-     Ppx_deriving.poly_arrow_of_type_decl f d y
+-   in
+-   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
+-
+-let write_sig_of_decl ({Parsetree.ptype_loc} as d) =
+-  (let s =
+-     let s = Ppx_deriving.mangle_type_decl (`Suffix "to_json") d in
+-     Location.mkloc s ptype_loc
+-   and y =
+-     let f y = [%type: Buffer.t -> [%t y] -> unit] in
+-     let y = f (Ppx_deriving.core_type_of_type_decl d) in
+-     Ppx_deriving.poly_arrow_of_type_decl f d y
+-   in
+-   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
+-
+-let json_sig_of_decl ({Parsetree.ptype_loc} as d) =
+-  (let s =
+-     let s = Ppx_deriving.mangle_type_decl (`Suffix "json") d in
+-     Location.mkloc s ptype_loc
+-   and y =
+-     let f y = [%type: [%t y] Deriving_Json.t] in
+-     let y = f (Ppx_deriving.core_type_of_type_decl d) in
+-     Ppx_deriving.poly_arrow_of_type_decl f d y
+-   in
+-   Ast_helper.Val.mk s y) |> Ast_helper.Sig.value
+-
+-let sigs_of_decl ({Parsetree.ptype_loc} as d) =
+-  Ast_helper.with_default_loc ptype_loc @@ fun () ->
+-  let l = [
+-    read_sig_of_decl d;
+-    write_sig_of_decl d;
+-    json_sig_of_decl d
+-  ] in
+-  match d with
+-  | { Parsetree.ptype_manifest =
+-        Some {Parsetree.ptyp_desc = Parsetree.Ptyp_variant _}} ->
+-    read_with_tag_sig_of_decl d :: recognize_sig_of_decl d :: l
+-  | _ ->
+-    l
+-
+-let register_for_expr s f =
+-  let core_type ({Parsetree.ptyp_loc} as y) =
+-    let f () = f y |> sanitize in
+-    Ast_helper.with_default_loc ptyp_loc f
+-  in
+-  Ppx_deriving.(create s ~core_type () |> register)
+-
+-let _ =
+-  register_for_expr "of_json" @@ fun y -> [%expr
+-    fun s ->
+-      [%e read_of_type y]
+-        (Deriving_Json_lexer.init_lexer (Lexing.from_string s))]
+-
+-let _ =
+-  register_for_expr "to_json" @@ fun y -> [%expr
+-    fun x ->
+-      let buf = Buffer.create 50 in
+-      [%e write_of_type y ~poly:false] buf x;
+-      Buffer.contents buf]
+-
+-let _ =
+-  let core_type ({Parsetree.ptyp_loc} as y) =
+-    let f () = json_of_type y |> sanitize in
+-    Ast_helper.with_default_loc ptyp_loc f
+-  and type_decl_str ~options ~path l =
+-    let lw, lr, lj, lp, lrv =
+-      let f d (lw, lr, lj, lp, lrv) =
+-        let w, r, j, p, rv = json_str_of_decl d in
+-        w :: lw, r :: lr, j :: lj,
+-        (match p with Some p -> p :: lp | None -> lp),
+-        (match rv with Some rv -> rv :: lrv | None -> lrv)
+-      and acc = [], [], [], [], [] in
+-      List.fold_right f l acc
+-    and f = Ast_helper.Str.value Asttypes.Recursive
+-    and f' = Ast_helper.Str.value Asttypes.Nonrecursive in
+-    let l = [f (lrv @ lr); f lw; f' lj] in
+-    match lp with [] -> l | _ -> f lp :: l
+-  and type_decl_sig ~options ~path l =
+-    List.map sigs_of_decl l |> List.flatten
+-  in
+-  Ppx_deriving.
+-    (create "json" ~core_type ~type_decl_str ~type_decl_sig ()
+-     |> register)
diff --git a/dev-ml/js_of_ocaml/js_of_ocaml-2.7.ebuild b/dev-ml/js_of_ocaml/js_of_ocaml-2.7.ebuild
index 420e7ae360aa..2de89b91ec30 100644
--- a/dev-ml/js_of_ocaml/js_of_ocaml-2.7.ebuild
+++ b/dev-ml/js_of_ocaml/js_of_ocaml-2.7.ebuild
@@ -31,6 +31,10 @@ RDEPEND="
 DEPEND="${RDEPEND}
 	dev-ml/ocamlbuild"
 
+src_prepare() {
+	has_version '>=dev-lang/ocaml-4.03' && epatch "${FILESDIR}/oc43.patch"
+}
+
 src_configure() {
 	printf "\n\n" >> Makefile.conf
 	use ocamlopt || echo "BEST := byte" >> Makefile.conf