Improve obj dup using spread syntax (rescript-lang#7043)

* obj_dup by spread syntax * add changelog

Author: cometkim

CHANGELOG.md

@@ -26,6 +26,7 @@
 - Improve bigint literal comparison. https://github.com/rescript-lang/rescript-compiler/pull/7029
 - Improve output of `@variadic` bindings. https://github.com/rescript-lang/rescript-compiler/pull/7030
 - Improve error messages around JSX components. https://github.com/rescript-lang/rescript-compiler/pull/7038
+- Improve output of record copying. https://github.com/rescript-lang/rescript-compiler/pull/7043
 
 # 12.0.0-alpha.3
 

jscomp/core/j.ml

@@ -159,7 +159,7 @@ and expression_desc =
  last step since "|0" can potentially be optimized
  *)
  | Number of number
- | Object of property_map
+ | Object of expression option * property_map
  | Undefined of {is_unit: bool}
  | Null
  | Await of expression

jscomp/core/js_analyzer.ml

@@ -99,7 +99,7 @@ let rec no_side_effect_expression_desc (x : J.expression_desc) =
  *)
  Ext_list.for_all xs no_side_effect
  | Optional_block (x, _) -> no_side_effect x
- | Object kvs -> Ext_list.for_all_snd kvs no_side_effect
+ | Object (_, kvs) -> Ext_list.for_all_snd kvs no_side_effect
  | String_append (a, b) | Seq (a, b) -> no_side_effect a && no_side_effect b
  | Length (e, _) | Caml_block_tag (e, _) | Typeof e -> no_side_effect e
  | Bin (op, a, b) -> op <> Eq && no_side_effect a && no_side_effect b

jscomp/core/js_dump.ml

@@ -109,7 +109,7 @@ let exn_block_as_obj ~(stack : bool) (el : J.expression list) (ext : J.tag_info)
  | _ -> assert false
  in
  Object
- (if stack then
+ (None, if stack then
  Ext_list.mapi_append el
  (fun i e -> (Js_op.Lit (field_name i), e))
  [ (Js_op.Lit "Error", E.new_ (E.js_global "Error") []) ]
@@ -725,9 +725,9 @@ and expression_desc cxt ~(level : int) f x : cxt =
  else E.runtime_call Js_runtime_modules.option "some" [ e ])
  | Caml_block (el, _, _, Blk_module fields) ->
  expression_desc cxt ~level f
- (Object
+ (Object (None,
  (Ext_list.map_combine fields el (fun x ->
- Js_op.Lit (Ext_ident.convert x))))
+ Js_op.Lit (Ext_ident.convert x)))))
  (*name convention of Record is slight different from modules*)
  | Caml_block (el, mutable_flag, _, Blk_record { fields; record_repr }) -> (
  if
@@ -738,24 +738,24 @@ and expression_desc cxt ~(level : int) f x : cxt =
  match record_repr with
  | Record_regular ->
  expression_desc cxt ~level f
- (Object (Ext_list.combine_array fields el (fun i -> Js_op.Lit i)))
+ (Object (None, Ext_list.combine_array fields el (fun i -> Js_op.Lit i)))
  | Record_optional ->
  let fields =
  Ext_list.array_list_filter_map fields el (fun f x ->
  match x.expression_desc with
  | Undefined _ -> None
  | _ -> Some (Js_op.Lit f, x))
  in
- expression_desc cxt ~level f (Object fields))
+ expression_desc cxt ~level f (Object (None, fields)))
  | Caml_block (el, _, _, Blk_poly_var _) -> (
  match el with
  | [ tag; value ] ->
  expression_desc cxt ~level f
- (Object
+ (Object (None,
  [
  (Js_op.Lit Literals.polyvar_hash, tag);
  (Lit Literals.polyvar_value, value);
- ])
+ ]))
  | _ -> assert false)
  | Caml_block (el, _, _, ((Blk_extension | Blk_record_ext _) as ext)) ->
  expression_desc cxt ~level f (exn_block_as_obj ~stack:false el ext)
@@ -793,7 +793,7 @@ and expression_desc cxt ~(level : int) f x : cxt =
  | Some t -> E.tag_type t )
  :: tails
  in
- expression_desc cxt ~level f (Object objs)
+ expression_desc cxt ~level f (Object (None, objs))
  | Caml_block (el, _, tag, Blk_constructor p) ->
  let not_is_cons = p.name <> Literals.cons in
  let tag_type = Ast_untagged_variants.process_tag_type p.attrs in
@@ -826,7 +826,7 @@ and expression_desc cxt ~(level : int) f x : cxt =
  | [(_, e)] when untagged -> e.expression_desc
  | _ when untagged -> assert false (* should not happen *)
  (* TODO: put restriction on the variant definitions allowed, to make sure this never happens. *)
- | _ -> J.Object objs in
+ | _ -> J.Object (None, objs) in
  expression_desc cxt ~level f exp
  | Caml_block
  ( _,
@@ -890,7 +890,7 @@ and expression_desc cxt ~(level : int) f x : cxt =
  P.group f 1 (fun _ -> expression ~level:3 cxt f e2)
  in
  if level > 2 then P.paren_vgroup f 1 action else action ()
- | Object lst ->
+ | Object (dup, lst) ->
  (* #1946 object literal is easy to be
  interpreted as block statement
  here we avoid parens in such case
@@ -899,11 +899,22 @@ and expression_desc cxt ~(level : int) f x : cxt =
  ]}
  *)
  P.cond_paren_group f (level > 1) (fun _ ->
- if lst = [] then (
- P.string f "{}";
- cxt)
+ let dup_expression e =
+ expression ~level:1 cxt f { e with expression_desc = J.Spread e }
+ in
+ if lst = [] then
+ P.brace f (fun _ -> match dup with Some e -> dup_expression e | _ -> cxt)
  else
- P.brace_vgroup f 1 (fun _ -> property_name_and_value_list cxt f lst))
+ P.brace_vgroup f 1 (fun _ ->
+ let cxt =
+ match dup with
+ | Some e ->
+ let cxt = dup_expression e in
+ comma_nl f;
+ cxt
+ | _ -> cxt
+ in
+ property_name_and_value_list cxt f lst))
  | Await e ->
  P.cond_paren_group f (level > 13) (fun _ ->
  P.string f "await ";

jscomp/core/js_exp_make.ml

@@ -251,7 +251,7 @@ let dummy_obj ?comment (info : Lam_tag_info.t) : t =
  match info with
  | Blk_record _ | Blk_module _ | Blk_constructor _ | Blk_record_inlined _
  | Blk_poly_var _ | Blk_extension | Blk_record_ext _ ->
- { comment; expression_desc = Object [] }
+ { comment; expression_desc = Object (None, []) }
  | Blk_tuple | Blk_module_export _ ->
  { comment; expression_desc = Array ([], Mutable) }
  | Blk_some | Blk_some_not_nested | Blk_lazy_general -> assert false
@@ -563,8 +563,8 @@ let rec string_append ?comment (e : t) (el : t) : t =
  { (concat a b ~delim) with comment }
  | _, _ -> { comment; expression_desc = String_append (e, el) }
 
-let obj ?comment properties : t =
- { expression_desc = Object properties; comment }
+let obj ?comment ?dup properties : t =
+ { expression_desc = Object (dup, properties); comment }
 
 let str_equal (txt0:string) (delim0:External_arg_spec.delim) txt1 delim1 =
  if delim0 = delim1 then

jscomp/core/js_exp_make.mli

@@ -317,7 +317,7 @@ val seq : ?comment:string -> t -> t -> t
 
 val fuse_to_seq : t -> t list -> t
 
-val obj : ?comment:string -> J.property_map -> t
+val obj : ?comment:string -> ?dup:J.expression -> J.property_map -> t
 
 val true_ : t
 

jscomp/core/js_fold.ml

@@ -169,8 +169,9 @@ class fold =
  let _self = _self#expression _x0 in
  _self
  | Number _ -> _self
- | Object _x0 ->
- let _self = _self#property_map _x0 in
+ | Object (_x0, _x1) ->
+ let _self = option (fun _self -> _self#expression) _self _x0 in
+ let _self = _self#property_map _x1 in
  _self
  | Undefined _ -> _self
  | Null -> _self

jscomp/core/js_record_fold.ml

@@ -175,8 +175,9 @@ let expression_desc : 'a. ('a, expression_desc) fn =
  let st = _self.expression _self st _x0 in
  st
  | Number _ -> st
- | Object _x0 ->
- let st = property_map _self st _x0 in
+ | Object (_x0, _x1) ->
+ let st = option _self.expression _self st _x0 in
+ let st = property_map _self st _x1 in
  st
  | Undefined _ -> st
  | Null -> st

jscomp/core/js_record_iter.ml

@@ -132,7 +132,9 @@ let expression_desc : expression_desc fn =
  _self.expression _self _x2
  | Caml_block_tag (_x0, _tag) -> _self.expression _self _x0
  | Number _ -> ()
- | Object _x0 -> property_map _self _x0
+ | Object (_x0, _x1) ->
+ option _self.expression _self _x0;
+ property_map _self _x1
  | Undefined _ -> ()
  | Null -> ()
  | Await _x0 -> _self.expression _self _x0

jscomp/core/js_record_map.ml

@@ -173,9 +173,10 @@ let expression_desc : expression_desc fn =
  let _x0 = _self.expression _self _x0 in
  Caml_block_tag (_x0, tag)
  | Number _ as v -> v
- | Object _x0 ->
- let _x0 = property_map _self _x0 in
- Object _x0
+ | Object (_x0, _x1) ->
+ let _x0 = option _self.expression _self _x0 in
+ let _x1 = property_map _self _x1 in
+ Object (_x0, _x1)
  | Undefined _ as v -> v
  | Null as v -> v
  | Await _x0 ->