Add reset to experimental_features to correctly reset playground (#7868)

* Add reset to experimental_features to correctly reset playground

* Changelog

Author: fhammerschmidt

CHANGELOG.md

@@ -23,6 +23,7 @@
 #### :bug: Bug fix
 
 - Fix code generation for emojis in polyvars and labels. https://github.com/rescript-lang/rescript/pull/7853
+- Add `reset` to `experimental_features` to correctly reset playground. https://github.com/rescript-lang/rescript/pull/7868
 - Fix crash with `@get` on external of type `unit => 'a`. https://github.com/rescript-lang/rescript/pull/7866
 
 #### :memo: Documentation
@@ -31,6 +32,8 @@
 
 #### :house: Internal
 
+- Playground: Add config options for experimental features and jsx preserve mode. https://github.com/rescript-lang/rescript/pull/7865
+
 # 12.0.0-beta.10
 
 #### :rocket: New Feature

compiler/jsoo/jsoo_playground_main.ml

@@ -378,6 +378,7 @@ module Compile = struct
   (* Responsible for resetting all compiler state as if it were a new instance *)
   let reset_compiler () =
     warning_infos := [||];
+    Experimental_features.reset ();
     flush_warning_buffer () |> ignore;
     Warnings.reset_fatal ();
     Env.reset_cache_toplevel ()

compiler/ml/experimental_features.ml

@@ -20,4 +20,6 @@ let enable_from_string (s : string) =
   | Some f -> enabled_features := FeatureSet.add f !enabled_features
   | None -> ()
 
+let reset () = enabled_features := FeatureSet.empty
+
 let is_enabled (f : feature) = FeatureSet.mem f !enabled_features

compiler/ml/experimental_features.mli

@@ -3,3 +3,4 @@ type feature = LetUnwrap
 val enable_from_string : string -> unit
 val is_enabled : feature -> bool
 val to_string : feature -> string
+val reset : unit -> unit