Remove @return(undefined_to_opt) and %undefined_to_opt primitive (#7462)

* Remove @return(undefined_to_opt) and %undefined_to_opt primitive

* Respect conversion semantics from undefined to option.

* Fix rewatch test

* CHANGELOG

---------

Co-authored-by: Cristiano Calcagno <cristianoc@users.noreply.github.com>

Author: cknitt

CHANGELOG.md

@@ -23,6 +23,10 @@
 
 - Better error message for when trying to await something that is not a promise. https://github.com/rescript-lang/rescript/pull/7561
 
+#### :house: Internal
+
+- Remove `@return(undefined_to_opt)` and `%undefined_to_opt` primitive. https://github.com/rescript-lang/rescript/pull/7462
+
 # 12.0.0-alpha.14
 
 #### :boom: Breaking Change

compiler/core/lam.ml

@@ -298,8 +298,8 @@ let rec apply ?(ap_transformed_jsx = false) fn args (ap_info : ap_info) : t =
           Lprim
             {
               primitive =
-                ( Pundefined_to_opt | Pnull_to_opt | Pnull_undefined_to_opt
-                | Pis_null | Pis_null_undefined | Ptypeof ) as wrap;
+                ( Pnull_to_opt | Pnull_undefined_to_opt | Pis_null
+                | Pis_null_undefined | Ptypeof ) as wrap;
               args =
                 [Lprim ({primitive = _; args = inner_args} as primitive_call)];
             };
@@ -442,11 +442,7 @@ let rec seq (a : t) b : t =
   match a with
   | Lprim {primitive = Pmakeblock _; args = x :: xs} ->
     seq (Ext_list.fold_left xs x seq) b
-  | Lprim
-      {
-        primitive = Pnull_to_opt | Pundefined_to_opt | Pnull_undefined_to_opt;
-        args = [a];
-      } ->
+  | Lprim {primitive = Pnull_to_opt | Pnull_undefined_to_opt; args = [a]} ->
     seq a b
   | _ -> Lsequence (a, b)
 
@@ -719,8 +715,6 @@ let result_wrap loc (result_type : External_ffi_types.return_wrapper) result =
   | Return_null_to_opt -> prim ~primitive:Pnull_to_opt ~args:[result] loc
   | Return_null_undefined_to_opt ->
     prim ~primitive:Pnull_undefined_to_opt ~args:[result] loc
-  | Return_undefined_to_opt ->
-    prim ~primitive:Pundefined_to_opt ~args:[result] loc
   | Return_unset | Return_identity -> result
 
 let handle_bs_non_obj_ffi ?(transformed_jsx = false)

compiler/core/lam_analysis.ml

@@ -46,8 +46,8 @@ let rec no_side_effects (lam : Lam.t) : bool =
       | _ -> false)
     | Pcreate_extension _ | Ptypeof | Pis_null | Pis_not_none | Psome
     | Psome_not_nest | Pis_undefined | Pis_null_undefined | Pnull_to_opt
-    | Pundefined_to_opt | Pnull_undefined_to_opt | Pjs_fn_make _
-    | Pjs_fn_make_unit | Pjs_object_create _ | Pimport
+    | Pnull_undefined_to_opt | Pjs_fn_make _ | Pjs_fn_make_unit
+    | Pjs_object_create _ | Pimport
     (* TODO: check *)
     | Pmakeblock _
     (* whether it's mutable or not *)

compiler/core/lam_compile_primitive.ml

@@ -95,13 +95,6 @@ let translate output_prefix loc (cxt : Lam_compile_context.t)
       | Var _ | Undefined _ | Null -> Js_of_lam_option.null_to_opt e
       | _ -> E.runtime_call Primitive_modules.option "fromNull" args)
     | _ -> assert false)
-  | Pundefined_to_opt -> (
-    match args with
-    | [e] -> (
-      match e.expression_desc with
-      | Var _ | Undefined _ | Null -> Js_of_lam_option.undef_to_opt e
-      | _ -> E.runtime_call Primitive_modules.option "fromUndefined" args)
-    | _ -> assert false)
   | Pnull_undefined_to_opt -> (
     match args with
     | [e] -> (

compiler/core/lam_convert.ml

@@ -197,7 +197,6 @@ let lam_prim ~primitive:(p : Lambda.primitive) ~args loc : Lam.t =
   | Pisnullable -> prim ~primitive:Pis_null_undefined ~args loc
   | Pnull_to_opt -> prim ~primitive:Pnull_to_opt ~args loc
   | Pnullable_to_opt -> prim ~primitive:Pnull_undefined_to_opt ~args loc
-  | Pundefined_to_opt -> prim ~primitive:Pundefined_to_opt ~args loc
   | Pis_not_none -> prim ~primitive:Pis_not_none ~args loc
   | Pval_from_option -> prim ~primitive:Pval_from_option ~args loc
   | Pval_from_option_not_nest ->

compiler/core/lam_pass_collect.ml

@@ -66,8 +66,6 @@ let collect_info (meta : Lam_stats.t) (lam : Lam.t) =
       collect v
     | Lprim {primitive = Pnull_to_opt; args = [(Lvar _ as l)]; _} ->
       Hash_ident.replace meta.ident_tbl ident (OptionalBlock (l, Null))
-    | Lprim {primitive = Pundefined_to_opt; args = [(Lvar _ as l)]; _} ->
-      Hash_ident.replace meta.ident_tbl ident (OptionalBlock (l, Undefined))
     | Lprim {primitive = Pnull_undefined_to_opt; args = [(Lvar _ as l)]} ->
       Hash_ident.replace meta.ident_tbl ident
         (OptionalBlock (l, Null_undefined))

compiler/core/lam_pass_deep_flatten.ml

@@ -123,8 +123,7 @@ let deep_flatten (lam : Lam.t) : Lam.t =
           id,
           (Lprim
              {
-               primitive =
-                 Pnull_to_opt | Pundefined_to_opt | Pnull_undefined_to_opt;
+               primitive = Pnull_to_opt | Pnull_undefined_to_opt;
                args = [Lvar _];
              } as arg),
           body ) ->
@@ -134,9 +133,7 @@ let deep_flatten (lam : Lam.t) : Lam.t =
           id,
           Lprim
             {
-              primitive =
-                (Pnull_to_opt | Pundefined_to_opt | Pnull_undefined_to_opt) as
-                primitive;
+              primitive = (Pnull_to_opt | Pnull_undefined_to_opt) as primitive;
               args = [arg];
             },
           body ) ->

compiler/core/lam_primitive.ml

@@ -161,7 +161,6 @@ type t =
      play safe first
   *)
   | Pjs_fn_method
-  | Pundefined_to_opt
   | Pnull_to_opt
   | Pnull_undefined_to_opt
   | Pis_null
@@ -224,12 +223,12 @@ let eq_primitive_approx (lhs : t) (rhs : t) =
   | Pawait
   (* etc *)
   | Pjs_apply | Pjs_runtime_apply | Pval_from_option | Pval_from_option_not_nest
-  | Pundefined_to_opt | Pnull_to_opt | Pnull_undefined_to_opt | Pis_null
-  | Pis_not_none | Psome | Psome_not_nest | Pis_undefined | Pis_null_undefined
-  | Pimport | Ptypeof | Pfn_arity | Pis_poly_var_block | Pdebugger | Pinit_mod
-  | Pupdate_mod | Pduprecord | Pmakearray | Parraylength | Parrayrefu
-  | Parraysetu | Parrayrefs | Parraysets | Pjs_fn_make_unit | Pjs_fn_method
-  | Phash | Phash_mixstring | Phash_mixint | Phash_finalmix ->
+  | Pnull_to_opt | Pnull_undefined_to_opt | Pis_null | Pis_not_none | Psome
+  | Psome_not_nest | Pis_undefined | Pis_null_undefined | Pimport | Ptypeof
+  | Pfn_arity | Pis_poly_var_block | Pdebugger | Pinit_mod | Pupdate_mod
+  | Pduprecord | Pmakearray | Parraylength | Parrayrefu | Parraysetu
+  | Parrayrefs | Parraysets | Pjs_fn_make_unit | Pjs_fn_method | Phash
+  | Phash_mixstring | Phash_mixint | Phash_finalmix ->
     rhs = lhs
   | Pcreate_extension a -> (
     match rhs with

compiler/core/lam_primitive.mli

@@ -152,7 +152,6 @@ type t =
   | Pjs_fn_make of int
   | Pjs_fn_make_unit
   | Pjs_fn_method
-  | Pundefined_to_opt
   | Pnull_to_opt
   | Pnull_undefined_to_opt
   | Pis_null

compiler/core/lam_print.ml

@@ -61,7 +61,6 @@ let primitive ppf (prim : Lam_primitive.t) =
   | Praw_js_code _ -> fprintf ppf "[raw]"
   | Ptypeof -> fprintf ppf "typeof"
   | Pnull_to_opt -> fprintf ppf "[null->opt]"
-  | Pundefined_to_opt -> fprintf ppf "[undefined->opt]"
   | Pnull_undefined_to_opt -> fprintf ppf "[null/undefined->opt]"
   | Pis_null -> fprintf ppf "[?null]"
   | Pis_not_none -> fprintf ppf "[?is-not-none]"