Toplevel: fix for when use-js-strings is disabled

Author: vouillon

CHANGES.md

@@ -49,6 +49,7 @@
 * Runtime: fix caml_string_concat when not using JS strings (#1874)
 * Runtime: consistent bigarray hashing across all architectures (#1977)
 * Tools: fix jsoo_mktop and jsoo_mkcmis (#1877)
+* Toplevel: fix for when use-js-strings is disabled (#1997)
 
 # 6.0.1 (2025-02-07) - Lille
 

lib/runtime/jsoo_runtime.ml

@@ -133,10 +133,10 @@ module Sys = struct
       | `Double_translation
       ]
 
-    external effects_ : unit -> string = "caml_jsoo_flags_effects"
+    external effects_ : unit -> Js.t = "caml_jsoo_flags_effects"
 
     let effects () =
-      match effects_ () with
+      match Js.to_string (effects_ ()) with
       | "disabled" -> `Disabled
       | "cps" -> `Cps
       | "double-translation" -> `Double_translation