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ocsigen · Apr 7, 2020 · 724ffbf · 724ffbf
1 parent 32e7aa9
commit 724ffbf
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/runtime/marshal.js b/runtime/marshal.js
@@ -455,7 +455,7 @@ var caml_legacy_custom_code = true
 //Requires: MlBytes, caml_ml_bytes_length, caml_bytes_unsafe_get
 //Requires: caml_ml_string_length, caml_string_unsafe_get
 //Requires: MlObjectTable, caml_list_to_js_array, caml_legacy_custom_code, caml_custom_ops
-//Requires: caml_invalid_argument
+//Requires: caml_invalid_argument,caml_string_of_jsbytes
 var caml_output_val = function (){
   function Writer () { this.chunk = []; }
   Writer.prototype = {
@@ -565,6 +565,9 @@ var caml_output_val = function (){
         writer.size_64 += v.length;
         if (v.length > 1) stack.push (v, 1);
       } else if (v instanceof MlBytes) {
+        if(!(caml_string_of_jsbytes("") instanceof MlBytes)) {
+          caml_failwith("output_value: [Bytes.t] cannot safely be marshaled with [--enable use-js-string]");
+        }
         if (memo(v)) return;
         var len = caml_ml_bytes_length(v);
         if (len < 0x20)