Only index the buffer if the query needs lit

Suggested-by: Liam Stevenson <[email protected]>

Author: voodoos

src/kernel/mtyper.ml

@@ -27,7 +27,7 @@ type ('p, 't) item =
     part_errors : exn list;
     part_checks : Typecore.delayed_check list;
     part_warnings : Warnings.state;
-    part_index : index
+    part_index : index lazy_t
   }
 
 type typedtree =
@@ -110,7 +110,9 @@ let[@tail_mod_cons] rec type_structure config caught env index sg = function
     let items, sg', part_env =
       Typemod.merlin_type_structure env sg [ parsetree_item ]
     in
-    let part_index = !index_items index config (`Impl items.str_items) in
+    let part_index =
+      lazy (!index_items (Lazy.force index) config (`Impl items.str_items))
+    in
     let typedtree_items =
       (items.Typedtree.str_items, items.Typedtree.str_type)
     in
@@ -146,7 +148,9 @@ let[@tail_mod_cons] rec type_signature config caught env index sg psg_modalities
            [ parsetree_item ])
     in
     let part_rev_sg = List.rev_append sig_type sg in
-    let part_index = !index_items index config (`Intf sig_items) in
+    let part_index =
+      lazy (!index_items (Lazy.force index) config (`Intf sig_items))
+    in
     let item =
       { parsetree_item;
         typedtree_items = (sig_items, sig_type);
@@ -184,7 +188,7 @@ let type_implementation config caught parsetree =
         ident_stamp,
         uid_stamp,
         Warnings.backup (),
-        Shape.Uid.Map.empty )
+        lazy Shape.Uid.Map.empty )
     | x :: _ ->
       caught := x.part_errors;
       Typecore.delayed_checks := x.part_checks;
@@ -235,7 +239,7 @@ let type_interface config caught (parsetree : Parsetree.signature) =
         ident_stamp,
         uid_stamp,
         Warnings.backup (),
-        Shape.Uid.Map.empty )
+        lazy Shape.Uid.Map.empty )
     | x :: _ ->
       caught := x.part_errors;
       Typecore.delayed_checks := x.part_checks;
@@ -360,7 +364,7 @@ let get_index t =
   let of_items items =
     List.last items
     |> Option.value_map ~default:Shape.Uid.Map.empty
-         ~f:(fun { part_index; _ } -> part_index)
+         ~f:(fun { part_index; _ } -> Lazy.force part_index)
   in
   match t.typedtree with
   | Implementation_items items -> of_items items