* Compatible for php8.1.

lib/purifier/HTMLPurifier/PropertyListIterator.php

@@ -29,6 +29,7 @@ class HTMLPurifier_PropertyListIterator extends FilterIterator
     /**
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function accept()
     {
         $key = $this->getInnerIterator()->key();

lib/purifier/HTMLPurifier/StringHash.php

@@ -20,6 +20,7 @@ class HTMLPurifier_StringHash extends ArrayObject
      * @param mixed $index
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($index)
     {
         $this->accessed[$index] = true;