Do not traverse merlin.hide nodes to index occs

src/analysis/ast_iterators.ml

@@ -44,8 +44,35 @@ let build_uid_to_locs_tbl ~(local_defs : Mtyper.typedtree) () =
     iter.structure iter str end;
   uid_to_locs_tbl
 
+let has_attribute ~name attrs =
+  List.exists ~f:(fun a ->
+    let (str,_) = Ast_helper.Attr.as_tuple a in
+    str.Location.txt = name
+  ) attrs
+
+let is_hidden attrs =
+  has_attribute ~name:"merlin.hide" attrs
+
 let iter_on_usages ~f (local_defs : Mtyper.typedtree) =
-  let iter = Cmt_format.iter_on_occurrences ~f in
+  let occ_iter = Cmt_format.iter_on_occurrences ~f in
+  let iter =
+    { occ_iter with
+      (* We avoid iterating on nodes that do not correspond to actual syntax
+         such as the ones introduced by PPXes *)
+      module_binding = (fun sub ({ mb_attributes; _ } as mb) ->
+        if not (is_hidden mb_attributes) then
+          occ_iter.module_binding sub mb);
+      include_infos = (fun sub f ({ incl_attributes; _ } as incl) ->
+        if not (is_hidden incl_attributes) then
+          occ_iter.include_infos sub f incl);
+      expr = (fun sub ({ exp_attributes; _ } as e) ->
+        if not (is_hidden exp_attributes) then
+          occ_iter.expr sub e);
+      pat = (fun sub ({ pat_attributes;  _ } as p) ->
+        if not (is_hidden pat_attributes) then
+          occ_iter.pat sub p);
+    }
+  in
   begin match local_defs with
   | `Interface signature -> iter.signature iter signature
   | `Implementation structure -> iter.structure iter structure end

src/ocaml/typing/tast_iterator.ml

@@ -34,6 +34,7 @@ type iterator =
     env: iterator -> Env.t -> unit;
     expr: iterator -> expression -> unit;
     extension_constructor: iterator -> extension_constructor -> unit;
+    include_infos: 'a. iterator -> ('a -> unit) -> 'a include_infos -> unit;
     location: iterator -> Location.t -> unit;
     module_binding: iterator -> module_binding -> unit;
     module_coercion: iterator -> module_coercion -> unit;
@@ -146,7 +147,7 @@ let structure_item sub {str_loc; str_desc; str_env; _} =
   | Tstr_class_type list ->
       List.iter (fun (_, s, cltd) ->
         iter_loc sub s; sub.class_type_declaration sub cltd) list
-  | Tstr_include incl -> include_infos sub (sub.module_expr sub) incl
+  | Tstr_include incl -> sub.include_infos sub (sub.module_expr sub) incl
   | Tstr_open od -> sub.open_declaration sub od
   | Tstr_attribute attr -> sub.attribute sub attr
 
@@ -407,7 +408,7 @@ let signature_item sub {sig_loc; sig_desc; sig_env; _} =
   | Tsig_recmodule list -> List.iter (sub.module_declaration sub) list
   | Tsig_modtype x -> sub.module_type_declaration sub x
   | Tsig_modtypesubst x -> sub.module_type_declaration sub x
-  | Tsig_include incl -> include_infos sub (sub.module_type sub) incl
+  | Tsig_include incl -> sub.include_infos sub (sub.module_type sub) incl
   | Tsig_class list -> List.iter (sub.class_description sub) list
   | Tsig_class_type list -> List.iter (sub.class_type_declaration sub) list
   | Tsig_open od -> sub.open_description sub od
@@ -663,6 +664,7 @@ let default_iterator =
     env;
     expr;
     extension_constructor;
+    include_infos;
     location;
     module_binding;
     module_coercion;

src/ocaml/typing/tast_iterator.mli

@@ -38,6 +38,7 @@ type iterator =
     env: iterator -> Env.t -> unit;
     expr: iterator -> expression -> unit;
     extension_constructor: iterator -> extension_constructor -> unit;
+    include_infos: 'a . iterator -> ('a -> unit) -> 'a include_infos -> unit;
     location: iterator -> Location.t -> unit;
     module_binding: iterator -> module_binding -> unit;
     module_coercion: iterator -> module_coercion -> unit;

tests/test-dirs/with-ppx/issue1671-string.t

@@ -59,16 +59,6 @@ Merlin should ignore hidden nodes in occurrences results
           "line": 1,
           "col": 7
         }
-      },
-      {
-        "start": {
-          "line": 3,
-          "col": 93
-        },
-        "end": {
-          "line": 3,
-          "col": 94
-        }
       }
     ],
     "notifications": []