improve variadic call using spread syntax

CHANGELOG.md

@@ -19,6 +19,7 @@
 #### :nail_care: Polish
 
 - 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
 
 # 12.0.0-alpha.3
 

jscomp/core/j.ml

@@ -163,6 +163,7 @@ and expression_desc =
   | Undefined of {is_unit: bool}
   | Null
   | Await of expression
+  | Spread of expression
 
 and for_ident_expression = expression
 (* pure*)

jscomp/core/js_analyzer.ml

@@ -109,6 +109,7 @@ let rec no_side_effect_expression_desc (x : J.expression_desc) =
   (* actually true? *) ->
       false
   | Await _ -> false
+  | Spread _ -> false
 
 and no_side_effect (x : J.expression) =
   no_side_effect_expression_desc x.expression_desc
@@ -212,6 +213,7 @@ let rec eq_expression ({ expression_desc = x0 } : J.expression)
   | Number (Uint _) ->
       false
   | Await _ -> false
+  | Spread _ -> false
 
 and eq_expression_list xs ys = Ext_list.for_all2_no_exn xs ys eq_expression
 

jscomp/core/js_dump.ml

@@ -162,6 +162,7 @@ let rec exp_need_paren ?(arrow=false) (e : J.expression) =
   | Js_not _ | Bool _ | New _ ->
       false
   | Await _ -> false
+  | Spread _ -> false
   | Tagged_template _ -> false
   | Optional_block (e, true) when arrow -> exp_need_paren ~arrow e
   | Optional_block _ -> false
@@ -907,6 +908,10 @@ and expression_desc cxt ~(level : int) f x : cxt =
       P.cond_paren_group f (level > 13) (fun _ ->
           P.string f "await ";
           expression ~level:13 cxt f e)
+  | Spread e ->
+      P.cond_paren_group f (level > 13) (fun _ ->
+          P.string f "...";
+          expression ~level:13 cxt f e)
 
 and property_name_and_value_list cxt f (l : J.property_map) =
   iter_lst cxt f l

jscomp/core/js_exp_make.ml

@@ -1368,3 +1368,9 @@ let neq_null_undefined_boolean ?comment (a : t) (b : t) =
 
 let make_exception (s : string) =
   pure_runtime_call Js_runtime_modules.exceptions Literals.create [ str s ]
+
+let rec variadic_args (args : t list) =
+  match args with
+  | [] -> []
+  | [last] -> [{ last with expression_desc = Spread last }]
+  | arg :: args -> arg :: variadic_args args

jscomp/core/js_exp_make.mli

@@ -364,3 +364,5 @@ val for_sure_js_null_undefined : J.expression -> bool
 val is_null_undefined : ?comment:string -> t -> t
 
 val make_exception : string -> t
+
+val variadic_args : t list -> t list

jscomp/core/js_fold.ml

@@ -177,6 +177,9 @@ class fold =
       | Await _x0 ->
         let _self = _self#expression _x0 in
         _self
+      | Spread _x0 ->
+        let _self = _self#expression _x0 in
+        _self
 
     method for_ident_expression : for_ident_expression -> 'self_type =
       _self#expression

jscomp/core/js_record_fold.ml

@@ -183,6 +183,9 @@ let expression_desc : 'a. ('a, expression_desc) fn =
   | Await _x0 ->
     let st = _self.expression _self st _x0 in
     st
+  | Spread _x0 ->
+    let st = _self.expression _self st _x0 in
+    st
 
 let for_ident_expression : 'a. ('a, for_ident_expression) fn =
  fun _self arg -> _self.expression _self arg

jscomp/core/js_record_iter.ml

@@ -136,6 +136,7 @@ let expression_desc : expression_desc fn =
   | Undefined _ -> ()
   | Null -> ()
   | Await _x0 -> _self.expression _self _x0
+  | Spread _x0 -> _self.expression _self _x0
 
 let for_ident_expression : for_ident_expression fn =
  fun _self arg -> _self.expression _self arg

jscomp/core/js_record_map.ml

@@ -181,6 +181,9 @@ let expression_desc : expression_desc fn =
   | Await _x0 ->
     let _x0 = _self.expression _self _x0 in
     Await _x0
+  | Spread _x0 ->
+    let _x0 = _self.expression _self _x0 in
+    Spread _x0
 
 let for_ident_expression : for_ident_expression fn =
  fun _self arg -> _self.expression _self arg

jscomp/core/lam_compile_external_call.ml

@@ -26,18 +26,6 @@
 
 module E = Js_exp_make
 
-let splice_apply fn args =
-  E.runtime_call Js_runtime_modules.caml_splice_call "spliceApply"
-    [ fn; E.array Immutable args ]
-
-let splice_new_apply fn args =
-  E.runtime_call Js_runtime_modules.caml_splice_call "spliceNewApply"
-    [ fn; E.array Immutable args ]
-
-let splice_obj_apply obj name args =
-  E.runtime_call Js_runtime_modules.caml_splice_call "spliceObjApply"
-    [ obj; E.str name; E.array Immutable args ]
-
 (** 
    [bind_name] is a hint to the compiler to generate 
    better names for external module 
@@ -278,17 +266,18 @@ let translate_ffi (cxt : Lam_compile_context.t) arg_types
       (match args with
       | [ {expression_desc = Array (strings, _); _}; {expression_desc = Array (values, _); _} ] -> 
         E.tagged_template fn strings values
-      | _ -> let args, eff, dynamic = assemble_args_has_splice arg_types args in
-        add_eff eff
-          (if dynamic then splice_apply fn args
-          else E.call ~info:{ arity = Full; call_info = Call_na } fn args))
+      | _ ->
+        let args, eff, dynamic = assemble_args_has_splice arg_types args in
+        let args = if dynamic then E.variadic_args args else args in
+        add_eff eff (
+          E.call ~info:{ arity = Full; call_info = Call_na } fn args))
   | Js_call { external_module_name = module_name; name = fn; splice; scopes; tagged_template = false } ->
       let fn = translate_scoped_module_val module_name fn scopes ~dynamic_import in
       if splice then
         let args, eff, dynamic = assemble_args_has_splice arg_types args in
-        add_eff eff
-          (if dynamic then splice_apply fn args
-          else E.call ~info:{ arity = Full; call_info = Call_na } fn args)
+        let args = if dynamic then E.variadic_args args else args in
+        add_eff eff (
+          E.call ~info:{ arity = Full; call_info = Call_na } fn args)
       else
         let args, eff = assemble_args_no_splice arg_types args in
         add_eff eff
@@ -297,10 +286,9 @@ let translate_ffi (cxt : Lam_compile_context.t) arg_types
       let fn = external_var external_module_name ~dynamic_import in
       if splice then
         let args, eff, dynamic = assemble_args_has_splice arg_types args in
-        (* TODO: fix in rest calling convention *)
-        add_eff eff
-          (if dynamic then splice_apply fn args
-          else E.call ~info:{ arity = Full; call_info = Call_na } fn args)
+        let args = if dynamic then E.variadic_args args else args in
+        add_eff eff (
+          E.call ~info:{ arity = Full; call_info = Call_na } fn args)
       else
         let args, eff = assemble_args_no_splice arg_types args in
         (* TODO: fix in rest calling convention *)
@@ -324,11 +312,11 @@ let translate_ffi (cxt : Lam_compile_context.t) arg_types
       in
       if splice then
         let args, eff, dynamic = assemble_args_has_splice arg_types args in
+        let args = if dynamic then E.variadic_args args else args in
         let fn = translate_scoped_module_val module_name fn scopes ~dynamic_import in
         add_eff eff
           (mark ();
-          if dynamic then splice_new_apply fn args
-          else E.new_ fn args)
+          E.new_ fn args)
       else
         let args, eff = assemble_args_no_splice arg_types args in
         let fn = translate_scoped_module_val module_name fn scopes ~dynamic_import in
@@ -342,13 +330,12 @@ let translate_ffi (cxt : Lam_compile_context.t) arg_types
           let[@warning "-8"] (_self_type :: arg_types) = arg_types in
           if splice then
             let args, eff, dynamic = assemble_args_has_splice arg_types args in
+            let args = if dynamic then E.variadic_args args else args in
             add_eff eff
               (let self = translate_scoped_access js_send_scopes self in
-               if dynamic then splice_obj_apply self name args
-               else
-                 E.call
-                   ~info:{ arity = Full; call_info = Call_na }
-                   (E.dot self name) args)
+                E.call
+                  ~info:{ arity = Full; call_info = Call_na }
+                  (E.dot self name) args)
           else
             let args, eff = assemble_args_no_splice arg_types args in
             add_eff eff

jscomp/ext/js_runtime_modules.ml

@@ -67,8 +67,6 @@ let module_ = "Caml_module"
 
 let caml_js_exceptions = "Caml_js_exceptions"
 
-let caml_splice_call = "Caml_splice_call"
-
 let deriving = "Runtime_deriving"
 
 let promise = "Runtime_promise"

jscomp/runtime/release.ninja

@@ -47,8 +47,6 @@ o runtime/caml_option.cmj : cc_cmi runtime/caml_option.res | runtime/caml_option
 o runtime/caml_option.cmi : cc runtime/caml_option.resi | runtime/bs_stdlib_mini.cmi runtime/caml_undefined_extern.cmj runtime/js.cmi runtime/js.cmj
 o runtime/caml_parser.cmj : cc_cmi runtime/caml_parser.res | runtime/caml_parser.cmi
 o runtime/caml_parser.cmi : cc runtime/caml_parser.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
-o runtime/caml_splice_call.cmj : cc_cmi runtime/caml_splice_call.res | runtime/caml_splice_call.cmi
-o runtime/caml_splice_call.cmi : cc runtime/caml_splice_call.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_string.cmj : cc_cmi runtime/caml_string.res | runtime/caml_string.cmi runtime/caml_string_extern.cmj
 o runtime/caml_string.cmi : cc runtime/caml_string.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_sys.cmj : cc_cmi runtime/caml_sys.res | runtime/caml_array_extern.cmj runtime/caml_sys.cmi runtime/caml_undefined_extern.cmj
@@ -62,4 +60,4 @@ o runtime/caml_nativeint_extern.cmi runtime/caml_nativeint_extern.cmj : cc runti
 o runtime/caml_string_extern.cmi runtime/caml_string_extern.cmj : cc runtime/caml_string_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_undefined_extern.cmi runtime/caml_undefined_extern.cmj : cc runtime/caml_undefined_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/curry.cmi runtime/curry.cmj : cc runtime/curry.res | runtime/bs_stdlib_mini.cmi runtime/caml_array.cmj runtime/caml_array_extern.cmj runtime/js.cmi runtime/js.cmj
-o runtime : phony runtime/bs_stdlib_mini.cmi runtime/js.cmj runtime/js.cmi runtime/caml.cmi runtime/caml.cmj runtime/caml_array.cmi runtime/caml_array.cmj runtime/caml_bigint.cmi runtime/caml_bigint.cmj runtime/caml_bytes.cmi runtime/caml_bytes.cmj runtime/caml_exceptions.cmi runtime/caml_exceptions.cmj runtime/caml_float.cmi runtime/caml_float.cmj runtime/caml_format.cmi runtime/caml_format.cmj runtime/caml_hash.cmi runtime/caml_hash.cmj runtime/caml_hash_primitive.cmi runtime/caml_hash_primitive.cmj runtime/caml_int32.cmi runtime/caml_int32.cmj runtime/caml_int64.cmi runtime/caml_int64.cmj runtime/caml_lexer.cmi runtime/caml_lexer.cmj runtime/caml_md5.cmi runtime/caml_md5.cmj runtime/caml_module.cmi runtime/caml_module.cmj runtime/caml_obj.cmi runtime/caml_obj.cmj runtime/caml_option.cmi runtime/caml_option.cmj runtime/caml_parser.cmi runtime/caml_parser.cmj runtime/caml_splice_call.cmi runtime/caml_splice_call.cmj runtime/caml_string.cmi runtime/caml_string.cmj runtime/caml_sys.cmi runtime/caml_sys.cmj runtime/caml_array_extern.cmi runtime/caml_array_extern.cmj runtime/caml_bigint_extern.cmi runtime/caml_bigint_extern.cmj runtime/caml_float_extern.cmi runtime/caml_float_extern.cmj runtime/caml_int64_extern.cmi runtime/caml_int64_extern.cmj runtime/caml_js_exceptions.cmi runtime/caml_js_exceptions.cmj runtime/caml_nativeint_extern.cmi runtime/caml_nativeint_extern.cmj runtime/caml_string_extern.cmi runtime/caml_string_extern.cmj runtime/caml_undefined_extern.cmi runtime/caml_undefined_extern.cmj runtime/curry.cmi runtime/curry.cmj
+o runtime : phony runtime/bs_stdlib_mini.cmi runtime/js.cmj runtime/js.cmi runtime/caml.cmi runtime/caml.cmj runtime/caml_array.cmi runtime/caml_array.cmj runtime/caml_bigint.cmi runtime/caml_bigint.cmj runtime/caml_bytes.cmi runtime/caml_bytes.cmj runtime/caml_exceptions.cmi runtime/caml_exceptions.cmj runtime/caml_float.cmi runtime/caml_float.cmj runtime/caml_format.cmi runtime/caml_format.cmj runtime/caml_hash.cmi runtime/caml_hash.cmj runtime/caml_hash_primitive.cmi runtime/caml_hash_primitive.cmj runtime/caml_int32.cmi runtime/caml_int32.cmj runtime/caml_int64.cmi runtime/caml_int64.cmj runtime/caml_lexer.cmi runtime/caml_lexer.cmj runtime/caml_md5.cmi runtime/caml_md5.cmj runtime/caml_module.cmi runtime/caml_module.cmj runtime/caml_obj.cmi runtime/caml_obj.cmj runtime/caml_option.cmi runtime/caml_option.cmj runtime/caml_parser.cmi runtime/caml_parser.cmj runtime/caml_string.cmi runtime/caml_string.cmj runtime/caml_sys.cmi runtime/caml_sys.cmj runtime/caml_array_extern.cmi runtime/caml_array_extern.cmj runtime/caml_bigint_extern.cmi runtime/caml_bigint_extern.cmj runtime/caml_float_extern.cmi runtime/caml_float_extern.cmj runtime/caml_int64_extern.cmi runtime/caml_int64_extern.cmj runtime/caml_js_exceptions.cmi runtime/caml_js_exceptions.cmj runtime/caml_nativeint_extern.cmi runtime/caml_nativeint_extern.cmj runtime/caml_string_extern.cmi runtime/caml_string_extern.cmj runtime/caml_undefined_extern.cmi runtime/caml_undefined_extern.cmj runtime/curry.cmi runtime/curry.cmj