Fatal error Zend_Memory_Value not compatible with ArrayAccess

[Nuranto]

PHP Fatal error: During inheritance of ArrayAccess: Uncaught Exception: Deprecated Functionality: Return type of Zend_Memory_Value::offsetExists($offset) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /var/www/html/vendor/magento/zendframework1/library/Zend/Memory/Value.php

Here's a patch :

--- a/library/Zend/Memory/Value.php
+++ b/library/Zend/Memory/Value.php
@@ -86,7 +86,7 @@
      * @param integer $offset
      * @return boolean
      */
-    public function offsetExists($offset)
+    public function offsetExists(mixed $offset): bool
     {
         return $offset >= 0  &&  $offset < strlen($this->_value);
     }
@@ -98,7 +98,7 @@
      * @param integer $offset
      * @return string
      */
-    public function offsetGet($offset)
+    public function offsetGet(mixed $offset): mixed
     {
         return $this->_value[$offset];
     }
@@ -110,7 +110,7 @@
      * @param integer $offset
      * @param string $char
      */
-    public function offsetSet($offset, $char)
+    public function offsetSet(mixed $offset, mixed $value): void
     {
         $this->_value[$offset] = $char;
 
@@ -126,7 +126,7 @@
      *
      * @param integer $offset
      */
-    public function offsetUnset($offset)
+    public function offsetUnset(mixed $offset): void
     {
         unset($this->_value[$offset]);

cf magento/magento2#35335

[xmav]

Hi @Nuranto !
Could you please provide steps to reproduce for this issue ?

[Nuranto]

Yes, you can execute any of these methods on a PHP8.1 environment.