rest_index accepts anything

Author: janedbal

Diff for: stubs/core.stub

@@ -321,6 +321,7 @@ function get_defined_constants(bool $categorize = false): array {}
 
 /**
  * @param array<string> $long_options
+ * @param mixed $rest_index
  * @param-out int $rest_index
  * @return __benevolent<array<string,string>|array<string,false>|array<string,list<mixed>>|false>
  */