Add a few TODOs

src/ppx_deriving_yojson.ml

@@ -300,6 +300,11 @@ and desu_expr_of_only_typ ~path typ =
     raise_errorf ~loc:ptyp_loc "%s cannot be derived for %s"
                  deriver (Ppx_deriving.string_of_core_type typ)
 
+(* TODO: Do not wrap runtime around [@default ...].
+   We do currently and for instance the following doesn't currently work:
+   module List = struct let x = [1; 2] end
+   type t = {field : int list [@default List.x]} [@@deriving to_yojson]
+*)
 let wrap_runtime decls =
   Ppx_deriving.sanitize ~module_:(Lident "Ppx_deriving_yojson_runtime") decls
 

src_test/test_ppx_yojson.ml

@@ -505,6 +505,22 @@ let test_int_redefined ctxt =
   let expected = `Int 1 in
   assert_equal ~ctxt ~printer:show_json expected M.x
 
+(* TODO: Make this work *)
+(*
+let test_list_redefined ctxt =
+  let module M = struct
+    type redef_list =
+      | []
+      | (::) of int * int
+
+    type t = {field : int list} [@@deriving to_yojson]
+    let x = {field = List.([1;2])}
+  end
+  in
+  let expected = `List [`Int 1; `Int 2] in
+  assert_equal ~ctxt ~printer:show_json expected M.x
+*)
+
 let test_equality_redefined ctxt =
   let module M = struct
     module Pervasives = struct