Add hintFunctionParams inlay hints

CHANGES.md

@@ -1,8 +1,13 @@
 # unreleased
 
+## Features
+
+- Make `inlay-hint` for function parameters configurable (#1515)
+
 ## Fixes
 
 - Support for `class`, `class type`, `method` and `property` for `DocumentSymbol` query (#1487 fixes #1449)
+- Fix `inlay-hint` for function parameters (#1515)
 
 # 1.22.0
 

ocaml-lsp-server/src/config_data.ml

@@ -5,6 +5,7 @@ module InlayHints = struct
   type t =
     { hint_pattern_variables : bool [@key "hintPatternVariables"] [@default false]
     ; hint_let_bindings : bool [@key "hintLetBindings"] [@default false]
+    ; hint_function_params : bool [@key "hintFunctionParams"] [@default false]
     }
   [@@deriving_inline yojson] [@@yojson.allow_extra_fields]
 
@@ -16,6 +17,7 @@ module InlayHints = struct
      | `Assoc field_yojsons as yojson ->
        let hint_pattern_variables_field = ref Ppx_yojson_conv_lib.Option.None
        and hint_let_bindings_field = ref Ppx_yojson_conv_lib.Option.None
+       and hint_function_params_field = ref Ppx_yojson_conv_lib.Option.None
        and duplicates = ref []
        and extra = ref [] in
        let rec iter = function
@@ -35,6 +37,13 @@ module InlayHints = struct
                  hint_let_bindings_field := Ppx_yojson_conv_lib.Option.Some fvalue
                | Ppx_yojson_conv_lib.Option.Some _ ->
                  duplicates := field_name :: Ppx_yojson_conv_lib.( ! ) duplicates)
+            | "hintFunctionParams" ->
+              (match Ppx_yojson_conv_lib.( ! ) hint_function_params_field with
+               | Ppx_yojson_conv_lib.Option.None ->
+                 let fvalue = bool_of_yojson _field_yojson in
+                 hint_function_params_field := Ppx_yojson_conv_lib.Option.Some fvalue
+               | Ppx_yojson_conv_lib.Option.Some _ ->
+                 duplicates := field_name :: Ppx_yojson_conv_lib.( ! ) duplicates)
             | _ -> ());
            iter tail
          | [] -> ()
@@ -54,9 +63,13 @@ module InlayHints = struct
                (Ppx_yojson_conv_lib.( ! ) extra)
                yojson
            | [] ->
-             let hint_pattern_variables_value, hint_let_bindings_value =
+             let ( hint_pattern_variables_value
+                 , hint_let_bindings_value
+                 , hint_function_params_value )
+               =
                ( Ppx_yojson_conv_lib.( ! ) hint_pattern_variables_field
-               , Ppx_yojson_conv_lib.( ! ) hint_let_bindings_field )
+               , Ppx_yojson_conv_lib.( ! ) hint_let_bindings_field
+               , Ppx_yojson_conv_lib.( ! ) hint_function_params_field )
              in
              { hint_pattern_variables =
                  (match hint_pattern_variables_value with
@@ -66,6 +79,10 @@ module InlayHints = struct
                  (match hint_let_bindings_value with
                   | Ppx_yojson_conv_lib.Option.None -> false
                   | Ppx_yojson_conv_lib.Option.Some v -> v)
+             ; hint_function_params =
+                 (match hint_function_params_value with
+                  | Ppx_yojson_conv_lib.Option.None -> false
+                  | Ppx_yojson_conv_lib.Option.Some v -> v)
              }))
      | _ as yojson ->
        Ppx_yojson_conv_lib.Yojson_conv_error.record_list_instead_atom _tp_loc yojson
@@ -78,8 +95,13 @@ module InlayHints = struct
     (function
      | { hint_pattern_variables = v_hint_pattern_variables
        ; hint_let_bindings = v_hint_let_bindings
+       ; hint_function_params = v_hint_function_params
        } ->
        let bnds : (string * Ppx_yojson_conv_lib.Yojson.Safe.t) list = [] in
+       let bnds =
+         let arg = yojson_of_bool v_hint_function_params in
+         ("hintFunctionParams", arg) :: bnds
+       in
        let bnds =
          let arg = yojson_of_bool v_hint_let_bindings in
          ("hintLetBindings", arg) :: bnds
@@ -798,7 +820,12 @@ let default =
   { codelens = Some { enable = false }
   ; extended_hover = Some { enable = false }
   ; standard_hover = Some { enable = true }
-  ; inlay_hints = Some { hint_pattern_variables = false; hint_let_bindings = false }
+  ; inlay_hints =
+      Some
+        { hint_pattern_variables = false
+        ; hint_let_bindings = false
+        ; hint_function_params = false
+        }
   ; dune_diagnostics = Some { enable = true }
   ; syntax_documentation = Some { enable = false }
   ; merlin_jump_code_actions = Some { enable = false }

ocaml-lsp-server/src/inlay_hints.ml

@@ -29,12 +29,22 @@ let compute (state : State.t) { InlayHintParams.range; textDocument = { uri }; _
           c.hint_pattern_variables)
         |> Option.value ~default:false
       in
+      let hint_function_params =
+        Option.map state.configuration.data.inlay_hints ~f:(fun c ->
+          c.hint_function_params)
+        |> Option.value ~default:false
+      in
       Document.Merlin.with_pipeline_exn ~name:"inlay-hints" doc (fun pipeline ->
         let start = range.start |> Position.logical
         and stop = range.end_ |> Position.logical in
         let command =
           Query_protocol.Inlay_hints
-            (start, stop, hint_let_bindings, hint_pattern_variables, not inside_test)
+            ( start
+            , stop
+            , hint_let_bindings
+            , hint_pattern_variables
+            , hint_function_params
+            , not inside_test )
         in
         let hints = Query_commands.dispatch pipeline command in
         List.filter_map

ocaml-lsp-server/test/e2e-new/inlay_hints.ml

@@ -5,6 +5,7 @@ let apply_inlay_hints
       ?range
       ?(hint_pattern_variables = false)
       ?(hint_let_bindings = false)
+      ?(hint_function_params = true)
       ~source
       ()
   =
@@ -33,6 +34,7 @@ let apply_inlay_hints
               , `Assoc
                   [ "hintPatternVariables", `Bool hint_pattern_variables
                   ; "hintLetBindings", `Bool hint_let_bindings
+                  ; "hintFunctionParams", `Bool hint_function_params
                   ] )
             ])
       (InlayHint request)
@@ -99,3 +101,16 @@ let%expect_test "let bindings" =
   apply_inlay_hints ~hint_let_bindings:true ~source ();
   [%expect {| let f () = let y$: int$ = 0 in y |}]
 ;;
+
+let%expect_test "function params" =
+  let source = "let f a b c d = (a + b, c ^ string_of_bool d)" in
+  apply_inlay_hints ~source ();
+  [%expect
+    {| let f a$: int$ b$: int$ c$: string$ d$: bool$ = (a + b, c ^ string_of_bool d) |}]
+;;
+
+let%expect_test "function params (deactivated)" =
+  let source = "let f a b c d = (a + b, c ^ string_of_bool d)" in
+  apply_inlay_hints ~hint_function_params:false ~source ();
+  [%expect {| let f a b c d = (a + b, c ^ string_of_bool d) |}]
+;;