unused value declarations

Author: zth

compiler/ext/warnings.ml

@@ -380,8 +380,6 @@ let message = function
     "this pattern-matching is not exhaustive.\n\
      All clauses in this pattern-matching are guarded."
   | Unused_var v | Unused_var_strict v ->
-    (* TODO(actions) Prefix with `_` *)
-    (* TODO(actions) Remove variable *)
     Format.sprintf
       "unused variable %s.\n\n\
        Fix this by:\n\
@@ -397,9 +395,7 @@ let message = function
   | Duplicate_definitions (kind, cname, tc1, tc2) ->
     Printf.sprintf "the %s %s is defined in both types %s and %s." kind cname
       tc1 tc2
-  | Unused_value_declaration v ->
-    (* TODO(actions) Remove value declaration *)
-    "unused value " ^ v ^ "."
+  | Unused_value_declaration v -> "unused value " ^ v ^ "."
   | Unused_open s -> "unused open " ^ s ^ "."
   | Unused_type_declaration s ->
     (* TODO(actions) Remove type declaration *)

compiler/ml/cmt_utils.ml

@@ -14,6 +14,9 @@ type action_type =
   | PrefixVariableWithUnderscore
   | RemoveUnusedVariable
 
+(* TODO: 
+- Unused var in patterns (and aliases )*)
+
 type cmt_action = {loc: Location.t; action: action_type; description: string}
 
 let action_to_string = function
@@ -53,7 +56,7 @@ let emit_possible_actions_from_warning loc w =
   | Unused_match | Unreachable_case ->
     add_possible_action
       {loc; action = RemoveSwitchCase; description = "Remove switch case"}
-  | Unused_var _ | Unused_var_strict _ ->
+  | Unused_var _ | Unused_var_strict _ | Unused_value_declaration _ ->
     add_possible_action
       {
         loc;

compiler/ml/typedecl.ml

@@ -1906,7 +1906,6 @@ let transl_value_decl env loc valdecl =
   in
   let id, newenv =
     Env.enter_value valdecl.pval_name.txt v env ~check:(fun s ->
-        (* TODO(actions) Remove unused value or prefix with underscore *)
         Warnings.Unused_value_declaration s)
   in
   let desc =

tests/build_tests/actions/expected/Actions_RemoveUnusedValue_applied.res

@@ -0,0 +1,6 @@
+// actionFilter=RemoveUnusedVariable
+module M: {} = {}
+
+/* === AVAILABLE ACTIONS:
+- RemoveUnusedVariable - Remove unused variable
+*/

tests/build_tests/actions/fixtures/Actions_RemoveUnusedValue.res

@@ -0,0 +1,4 @@
+// actionFilter=RemoveUnusedVariable
+module M: {} = {
+  let x = 12
+}

tools/src/tools.ml

@@ -1318,7 +1318,14 @@ module Actions = struct
                        | None -> Some str_item)
                      | _ -> Some str_item)
             in
-            Ast_mapper.default_mapper.structure mapper items);
+            let items = Ast_mapper.default_mapper.structure mapper items in
+
+            (* Cleanup if needed *)
+            items
+            |> List.filter_map (fun (str_item : Parsetree.structure_item) ->
+                   match str_item.pstr_desc with
+                   | Pstr_value (_, []) -> None
+                   | _ -> Some str_item));
         value_bindings =
           (fun mapper bindings ->
             let remove_unused_variables_action_locs =