feat: allow melange to work with OCaml 4.14 (#1028)

* 4.14 conditionals

* 4.14 AST

* wip

* wip

bin/melc.ml

@@ -84,9 +84,11 @@ module As_ppx = struct
     Cmd_ppx_apply.apply_rewriters ~tool_name:"melppx" kind ast
 
 
+module Melange_ast_version = Melangelib.Ast_io.Melange_ast_version
+
 module Convert =
   Ppxlib_ast.Convert
-    (Ppxlib_ast__.Versions.OCaml_501)
+    (Melange_ast_version)
     (Ppxlib_ast__.Versions.OCaml_current)
 
 let apply_lazy ~source ~target =
@@ -98,7 +100,7 @@ let apply_lazy ~source ~target =
   | Intf ast ->
       let ast: Ppxlib_ast__.Versions.OCaml_current.Ast.Parsetree.signature =
         let ast = apply ~kind:Ml_binary.Mli ast in
-        let ppxlib_ast: Ppxlib_ast__.Versions.OCaml_501.Ast.Parsetree.signature =
+        let ppxlib_ast: Melange_ast_version.Ast.Parsetree.signature =
           Obj.magic ast
         in
         Convert.copy_signature ppxlib_ast
@@ -112,7 +114,7 @@ let apply_lazy ~source ~target =
         let ast: Melange_compiler_libs.Parsetree.structure =
           apply ~kind:Ml_binary.Ml ast
         in
-        let ppxlib_ast: Ppxlib_ast__.Versions.OCaml_501.Ast.Parsetree.structure =
+        let ppxlib_ast: Melange_ast_version.Ast.Parsetree.structure =
           Obj.magic ast
         in
         Convert.copy_structure ppxlib_ast

jscomp/core/ast_io.ml → jscomp/core/ast_io.cppo.ml

@@ -23,6 +23,14 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
 
 open Import
+
+module Melange_ast_version =
+#if OCAML_VERSION >= (5, 1, 0)
+  Ppxlib_ast__.Versions.OCaml_501
+#else
+  Ppxlib_ast__.Versions.OCaml_414
+#endif
+
 module Compiler_version = Ppxlib_ast.Compiler_version
 
 module type OCaml_version = Ppxlib_ast.OCaml_version
@@ -35,7 +43,7 @@ module Intf_or_impl = struct
   module Convert =
     Ppxlib_ast.Convert
       (Ppxlib_ast.Selected_ast)
-      (Ppxlib_ast__.Versions.OCaml_501)
+      (Melange_ast_version)
 
   let ppxlib_impl : Ppxlib_ast.Ast.structure -> t =
    fun stru ->

jscomp/core/ast_io.mli

@@ -23,6 +23,7 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, US. *)
 
 open Import
+module Melange_ast_version : Ppxlib_ast.OCaml_version
 module Compiler_version = Ppxlib_ast.Compiler_version
 
 module type OCaml_version = Ppxlib_ast.OCaml_version

jscomp/core/dune

@@ -8,6 +8,58 @@
   ppxlib.ast
   dune-build-info))
 
+(rule
+ (targets lam_convert.ml)
+ (deps lam_convert.cppo.ml)
+ (action
+  (run
+   cppo
+   -V
+   OCAML:%{ocaml_version}
+   %{env:CPPO_FLAGS=}
+   %{deps}
+   -o
+   %{targets})))
+
+(rule
+ (targets polyvar_pattern_match.ml)
+ (deps polyvar_pattern_match.cppo.ml)
+ (action
+  (run
+   cppo
+   -V
+   OCAML:%{ocaml_version}
+   %{env:CPPO_FLAGS=}
+   %{deps}
+   -o
+   %{targets})))
+
+(rule
+ (targets initialization.ml)
+ (deps initialization.cppo.ml)
+ (action
+  (run
+   cppo
+   -V
+   OCAML:%{ocaml_version}
+   %{env:CPPO_FLAGS=}
+   %{deps}
+   -o
+   %{targets})))
+
+(rule
+ (targets ast_io.ml)
+ (deps ast_io.cppo.ml)
+ (action
+  (run
+   cppo
+   -V
+   OCAML:%{ocaml_version}
+   %{env:CPPO_FLAGS=}
+   %{deps}
+   -o
+   %{targets})))
+
 (rule
  (target include_dirs.ml)
  (deps include_dirs.dev.ml include_dirs.release.ml)

jscomp/core/gen/record_fold.ml

@@ -202,7 +202,7 @@ let make type_declaration =
                     [
                       Typ.var "state"; Typ.constr { txt = Lident name; loc } [];
                     ])))
-           (StringSet.to_list customNames))
+           (StringSet.to_seq customNames |> List.of_seq))
     in
     let iter =
       Ast_helper.Type.mk
@@ -228,7 +228,7 @@ let make type_declaration =
            ~f:(fun s ->
              let lid = { Asttypes.txt = Longident.Lident s; loc } in
              (lid, Ast_helper.Exp.ident lid))
-           (StringSet.to_list customNames))
+           (StringSet.to_seq customNames |> List.of_seq))
         None
     in
     [%stri let super : 'state iter = [%e super]]

jscomp/core/gen/record_iter.ml

@@ -189,7 +189,7 @@ let make type_declaration =
                Type.field { txt = name; loc }
                  (Typ.constr { txt = Lident "fn"; loc }
                     [ Typ.constr { txt = Lident name; loc } [] ])))
-           (StringSet.to_list customNames))
+           (StringSet.to_seq customNames |> List.of_seq))
     in
     let iter = Ast_helper.Type.mk ~kind:record { txt = "iter"; loc } in
     let fn =
@@ -206,7 +206,7 @@ let make type_declaration =
            ~f:(fun s ->
              let lid = { Asttypes.txt = Longident.Lident s; loc } in
              (lid, Ast_helper.Exp.ident lid))
-           (StringSet.to_list customNames))
+           (StringSet.to_seq customNames |> List.of_seq))
         None
     in
     [%stri let super : iter = [%e super]]

jscomp/core/gen/record_map.ml

@@ -219,7 +219,7 @@ let make type_declaration =
                Type.field { txt = name; loc }
                  (Typ.constr { txt = Lident "fn"; loc }
                     [ Typ.constr { txt = Lident name; loc } [] ])))
-           (StringSet.to_list customNames))
+           (StringSet.to_seq customNames |> List.of_seq))
     in
     let iter = Ast_helper.Type.mk ~kind:record { txt = "iter"; loc } in
     let fn =
@@ -236,7 +236,7 @@ let make type_declaration =
            ~f:(fun s ->
              let lid = { Asttypes.txt = Longident.Lident s; loc } in
              (lid, Ast_helper.Exp.ident lid))
-           (StringSet.to_list customNames))
+           (StringSet.to_seq customNames |> List.of_seq))
         None
     in
     [%stri let super : iter = [%e super]]

jscomp/core/initialization.ml → jscomp/core/initialization.cppo.ml

@@ -105,6 +105,9 @@ module Perfile = struct
     Typemod.initial_env
       ~loc:(Location.in_file "command line")
       ~initially_opened_module
+#if OCAML_VERSION < (5,0,0)
+      ~safe_string:true
+#endif
       ~open_implicit_modules:(List.rev !Clflags.open_modules)
 end
 

jscomp/core/lam_convert.ml → jscomp/core/lam_convert.cppo.ml

@@ -274,7 +274,11 @@ let lam_prim ~primitive:(p : Lambda.primitive) ~args loc : Lam.t =
       | Blk_na s ->
           let info : Lam.Tag_info.t = Blk_na s in
           prim ~primitive:(Pmakeblock (tag, info, mutable_flag)) ~args loc)
+#if OCAML_VERSION >= (5, 1, 0)
   | Pfield (id, _ptr, _mut, info) ->
+#else
+  | Pfield (id, info) ->
+#endif
       prim ~primitive:(Pfield (id, info)) ~args loc
   | Psetfield (id, _, _initialization_or_assignment, info) ->
       prim ~primitive:(Psetfield (id, info)) ~args loc
@@ -428,11 +432,13 @@ let lam_prim ~primitive:(p : Lambda.primitive) ~args loc : Lam.t =
   | Pbbswap i -> prim ~primitive:(Pbbswap i) ~args loc
   | Pbswap16 -> prim ~primitive:Pbswap16 ~args loc
   | Pduparray _ -> assert false
+#if OCAML_VERSION >= (5, 1, 0)
   | Prunstack | Pperform | Presume | Preperform | Patomic_exchange | Patomic_cas
   | Patomic_fetch_add | Pdls_get | Patomic_load _ ->
       Location.raise_errorf ~loc
         "OCaml 5 multicore primitives (Effect, Condition, Semaphore) are not \
          currently supported in Melange"
+#endif
 
 (* Does not exist since we compile array in js backend unlike native backend *)
 

jscomp/core/polyvar_pattern_match.ml → jscomp/core/polyvar_pattern_match.cppo.ml

@@ -125,5 +125,9 @@ let call_switcher_variant_constr (loc : Lambda.scoped_location)
     ( Alias,
       Pgenval,
       v,
+#if OCAML_VERSION >= (5, 1, 0)
       Lprim (Pfield (0, Pointer, Immutable, Fld_poly_var_tag), [ arg ], loc),
+#else
+      Lprim (Pfield (0, Fld_poly_var_tag), [ arg ], loc),
+#endif
       call_switcher_variant_constant loc fail (Lvar v) int_lambda_list names )

playground/mel_playground.ml

@@ -26,7 +26,7 @@ open Melstd
 open Melangelib
 open Melange_compiler_libs
 module Js = Jsoo_runtime.Js
-module Melange_OCaml_version = Ppxlib_ast__.Versions.OCaml_501
+module Melange_OCaml_version = Ast_io.Melange_ast_version
 
 module Melange_ast = struct
   external to_ppxlib :