Add active_param

src/frontend/ocamlmerlin/query_json.ml

@@ -356,11 +356,12 @@ let json_of_signature_help resp =
     `Assoc [ "label_start", `Int label_start; "label_end", `Int label_end] in
   match resp with
   | None -> `Assoc []
-  | Some { function_name; signature; parameters } ->
+  | Some { function_name; signature; parameters; active_param } ->
     `Assoc
       [ "function_name", `String (Option.value ~default:"_" function_name);
         "signature", `String signature;
-        "parameters", `List (List.map ~f:param parameters)
+        "parameters", `List (List.map ~f:param parameters);
+        "active_param", `Int active_param
       ]
 
 let json_of_response (type a) (query : a t) (response : a) : json =

src/frontend/query_commands.ml

@@ -858,6 +858,7 @@ let dispatch pipeline (type a) : a Query_protocol.t -> a =
       Some { function_name = s.function_name;
         signature = s.signature;
         parameters = List.map ~f:(param (String.length prefix)) s.parameters;
+        active_param = Option.value ~default:0 s.active_param;
       }
     | None -> None)
 

src/frontend/query_protocol.ml

@@ -105,6 +105,7 @@ type signature_help = {
   function_name : string option;
   signature : string;
   parameters : signature_help_param list;
+  active_param : int
 }
 
 type is_tail_position = [`No | `Tail_position | `Tail_call]

tests/test-dirs/signature-help.t

@@ -18,7 +18,8 @@ It can provide signature help after a function-type value
           "label_start": 22,
           "label_end": 29
         }
-      ]
+      ],
+      "active_param": 1
     },
     "notifications": []
   }