remove [@mel.invoke] in favor of [@mel.this] on the core_type arg

jscomp/common/external_ffi_types.ml

@@ -46,7 +46,7 @@ type arg_type = External_arg_spec.attr
    hand *)
 
 type arg_label = External_arg_spec.Obj_label.t
-type js_send_kind = Send | Invoke | Pipe
+type js_send_kind = Pipe | Send of int
 
 type external_spec =
   | Js_var of {

jscomp/common/external_ffi_types.mli

@@ -39,7 +39,7 @@ type external_module_name = {
 
 type arg_type = External_arg_spec.attr
 type arg_label = External_arg_spec.Obj_label.t
-type js_send_kind = Send | Invoke | Pipe
+type js_send_kind = Pipe | Send of int
 
 type external_spec =
   | Js_var of {

jscomp/core/lam_compile_external_call.ml

@@ -266,44 +266,17 @@ let translate_scoped_module_val
           let start = E.js_global x in
           List.fold_left ~f:E.dot ~init:start (rest @ [ fn ]))
 
-let js_send_self_and_args =
-  let rec inner args arg_types (acc_args, acc_arg_types) =
-    match (args, arg_types) with
-    | [], [] -> assert false
-    | ( self :: args,
-        {
-          (* The "self" arg in `[@mel.send]` is the first non-labelled argument
-             that we find, e.g. `t` in `external foo: ?a:int -> t -> unit`.
-             This allows to write expressive bindings to JS that are applied
-             via dot-notation and still model the "self" arg after those in OCaml
-             such that those labels can be applied optionally. *)
-          External_arg_spec.arg_label = External_arg_spec.Arg_label.Arg_empty;
-          _;
-        }
-        :: arg_types ) ->
-        ( self,
-          List.rev_append acc_args args,
-          List.rev_append acc_arg_types arg_types )
-    | ( arg :: rest,
-        ({ arg_label = Arg_label | Arg_optional; _ } as arg_type) :: types_rest
-      ) ->
-        inner rest types_rest (arg :: acc_args, arg_type :: acc_arg_types)
-    | [], _ :: _ | _ :: _, [] -> assert false
-  in
-  fun args arg_types ~kind ->
-    match kind with
-    | External_ffi_types.Pipe -> assert false
-    | Send -> (
-        match args with
-        | self :: args ->
-            (* PR2162 [self_type] more checks in syntax:
+let js_send_self_and_args args arg_types ~self_idx =
+  (* PR2162 [self_type] more checks in syntax:
                  - should not be [@as] *)
-            let[@ocaml.warning "-partial-match"] (_self_type :: arg_types) =
-              arg_types
-            in
-            (self, args, arg_types)
-        | _ -> assert false)
-    | Invoke -> inner args arg_types ([], [])
+  let[@ocaml.warning "-partial-match"] args_pre, self :: args_post =
+    List.split_at args self_idx
+  in
+  let[@ocaml.warning "-partial-match"] ( arg_types_pre,
+                                         _self_types :: arg_types_post ) =
+    List.split_at arg_types self_idx
+  in
+  (self, args_pre @ args_post, arg_types_pre @ arg_types_post)
 
 let translate_ffi =
   let translate_scoped_access scopes obj =
@@ -412,9 +385,9 @@ let translate_ffi =
             add_eff eff
               (let self = translate_scoped_access scopes self in
                process_send ~new_ self name args)
-        | (Send | Invoke), true ->
+        | Send self_idx, true ->
             let self, args, arg_types =
-              js_send_self_and_args args arg_types ~kind
+              js_send_self_and_args args arg_types ~self_idx
             in
             let args, eff, dynamic = assemble_args_has_splice arg_types args in
             add_eff eff
@@ -424,9 +397,9 @@ let translate_ffi =
                  | true -> splice_fn_new_apply (E.dot self name) args
                  | false -> splice_obj_fn_apply self name args
                else process_send ~new_ self name args)
-        | (Send | Invoke), false ->
+        | Send self_idx, false ->
             let self, args, arg_types =
-              js_send_self_and_args args arg_types ~kind
+              js_send_self_and_args args arg_types ~self_idx
             in
             (* PR2162 [self_type] more checks in syntax:
                 - should not be [@mel.as] *)