Remove obj keys mangle

CHANGELOG.md

@@ -16,6 +16,10 @@
 
 - `rescript build` will always build its dependency by default. The argument `-with-deps` is not needed anymore. https://github.com/rescript-lang/rescript-compiler/pull/6350
 
+#### :boom: Breaking Change
+
+- Stop mangling object field names. If you had objects with field names containing "__" or leading "_", they won't be mangled in the compiled JavaScript and represented as it is without changes.  https://github.com/rescript-lang/rescript-compiler/pull/6354
+
 #### :bug: Bug Fix
 
 - Fixed outcome printer resolution of uncurried config. https://github.com/rescript-lang/rescript-compiler/pull/6353

jscomp/core/lam_convert.ml

@@ -602,10 +602,9 @@ let convert (exports : Set_ident.t) (lam : Lambda.lambda) :
         let setter = Ext_string.ends_with name Literals.setter_suffix in
         let property =
           if setter then
-            Lam_methname.translate
-              (String.sub name 0
-                 (String.length name - Literals.setter_suffix_len))
-          else Lam_methname.translate name
+            (String.sub name 0
+                (String.length name - Literals.setter_suffix_len))
+          else name
         in
         prim
           ~primitive:(Pjs_unsafe_downgrade { name = property; setter })

jscomp/frontend/ast_external_process.ml

@@ -406,29 +406,25 @@ let process_obj (loc : Location.t) (st : external_desc) (prim_name : string)
                   param_type :: arg_types,
                   result_types )
               | Arg_cst _ ->
-                let s = Lam_methname.translate name in
-                ( {obj_arg_label = External_arg_spec.obj_label s; obj_arg_type},
+                ( {obj_arg_label = External_arg_spec.obj_label name; obj_arg_type},
                   arg_types,
                   (* ignored in [arg_types], reserved in [result_types] *)
                   result_types )
               | Nothing ->
-                let s = Lam_methname.translate name in
-                ( {obj_arg_label = External_arg_spec.obj_label s; obj_arg_type},
+                ( {obj_arg_label = External_arg_spec.obj_label name; obj_arg_type},
                   param_type :: arg_types,
                   Parsetree.Otag ({Asttypes.txt = name; loc}, [], ty)
                   :: result_types )
               | Int _ ->
-                let s = Lam_methname.translate name in
-                ( {obj_arg_label = External_arg_spec.obj_label s; obj_arg_type},
+                ( {obj_arg_label = External_arg_spec.obj_label name; obj_arg_type},
                   param_type :: arg_types,
                   Otag
                     ( {Asttypes.txt = name; loc},
                       [],
                       Ast_literal.type_int ~loc () )
                   :: result_types )
               | Poly_var_string _ ->
-                let s = Lam_methname.translate name in
-                ( {obj_arg_label = External_arg_spec.obj_label s; obj_arg_type},
+                ( {obj_arg_label = External_arg_spec.obj_label name; obj_arg_type},
                   param_type :: arg_types,
                   Otag
                     ( {Asttypes.txt = name; loc},
@@ -453,7 +449,6 @@ let process_obj (loc : Location.t) (st : external_desc) (prim_name : string)
                   param_type :: arg_types,
                   result_types )
               | Nothing ->
-                let s = Lam_methname.translate name in
                 let for_sure_not_nested =
                   match ty.ptyp_desc with
                   | Ptyp_constr ({txt = Lident txt; _}, []) ->
@@ -462,7 +457,7 @@ let process_obj (loc : Location.t) (st : external_desc) (prim_name : string)
                 in
                 ( {
                     obj_arg_label =
-                      External_arg_spec.optional for_sure_not_nested s;
+                      External_arg_spec.optional for_sure_not_nested name;
                     obj_arg_type;
                   },
                   param_type :: arg_types,
@@ -472,9 +467,8 @@ let process_obj (loc : Location.t) (st : external_desc) (prim_name : string)
                       Ast_comb.to_undefined_type loc ty )
                   :: result_types )
               | Int _ ->
-                let s = Lam_methname.translate name in
                 ( {
-                    obj_arg_label = External_arg_spec.optional true s;
+                    obj_arg_label = External_arg_spec.optional true name;
                     obj_arg_type;
                   },
                   param_type :: arg_types,
@@ -485,9 +479,8 @@ let process_obj (loc : Location.t) (st : external_desc) (prim_name : string)
                       @@ Ast_literal.type_int ~loc () )
                   :: result_types )
               | Poly_var_string _ ->
-                let s = Lam_methname.translate name in
                 ( {
-                    obj_arg_label = External_arg_spec.optional true s;
+                    obj_arg_label = External_arg_spec.optional true name;
                     obj_arg_type;
                   },
                   param_type :: arg_types,
@@ -961,7 +954,7 @@ let pval_prim_of_labels (labels : string Asttypes.loc list) =
       ([] : External_arg_spec.obj_params)
       (fun p arg_kinds ->
         let obj_arg_label =
-          External_arg_spec.obj_label (Lam_methname.translate p.txt)
+          External_arg_spec.obj_label (p.txt)
         in
         {obj_arg_type = Nothing; obj_arg_label} :: arg_kinds)
   in
@@ -974,7 +967,7 @@ let pval_prim_of_option_labels (labels : (bool * string Asttypes.loc) list)
       (if ends_with_unit then [External_arg_spec.empty_kind Extern_unit]
       else [])
       (fun (is_option, p) arg_kinds ->
-        let label_name = Lam_methname.translate p.txt in
+        let label_name = p.txt in
         let obj_arg_label =
           if is_option then External_arg_spec.optional false label_name
           else External_arg_spec.obj_label label_name