Fixes to launch Magento with PHP 8.1

app/code/Magento/Analytics/Model/ReportXml/ModuleIterator.php

@@ -34,6 +34,7 @@ public function __construct(
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         $current = parent::current();

app/code/Magento/Analytics/ReportXml/Query.php

@@ -82,6 +82,7 @@ public function getConfig()
      * @return mixed data which can be serialized by <b>json_encode</b>,
      * which is a value of any type other than a resource.
      */
+    #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
         return [

app/code/Magento/Backend/App/DefaultPath.php

@@ -24,7 +24,8 @@ class DefaultPath implements \Magento\Framework\App\DefaultPathInterface
      */
     public function __construct(\Magento\Backend\App\ConfigInterface $config)
     {
-        $pathParts = explode('/', $config->getValue('web/default/admin'));
+        $path = $config->getValue('web/default/admin');
+        $pathParts = $path ? explode('/', $path) : [''];
 
         $this->_parts = [
             'area' => isset($pathParts[0]) ? $pathParts[0] : '',

app/code/Magento/Backend/Model/Menu.php

@@ -267,6 +267,7 @@ protected function _findParentItems($menu, $itemId, &$parents)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function serialize()
     {
         return $this->serializer->serialize($this->toArray());
@@ -294,7 +295,7 @@ public function toArray()
      * @return void
      * @since 100.2.0
      */
-    public function unserialize($serialized)
+    public function unserialize($serialized): void
     {
         $data = $this->serializer->unserialize($serialized);
         $this->populateFromArray($data);

app/code/Magento/Backend/Model/Menu/Filter/Iterator.php

@@ -27,6 +27,7 @@ public function __construct(\Iterator $iterator)
      *
      * @return bool true if the current element is acceptable, otherwise false.
      */
+    #[\ReturnTypeWillChange]
     public function accept()
     {
         return !($this->current()->isDisabled() || !$this->current()->isAllowed());

app/code/Magento/Backend/Model/Menu/Iterator.php

@@ -17,7 +17,7 @@ class Iterator extends \ArrayIterator
      *
      * @return void
      */
-    public function rewind()
+    public function rewind(): void
     {
         $this->ksort();
         parent::rewind();

app/code/Magento/Backend/view/adminhtml/templates/widget/tabshoriz.phtml

@@ -19,7 +19,7 @@ use Magento\Framework\View\Helper\SecureHtmlRenderer;
     <?php foreach ($tabs as $_tab): ?>
         <?php $tabId = $block->getTabId($_tab) ?>
         <?php $_tabClass = 'tab-item-link ' . $block->getTabClass($_tab) . ' ' .
-            (preg_match('/\s?ajax\s?/', $_tab->getClass()) ? 'notloaded' : '') ?>
+            (preg_match('/\s?ajax\s?/', $_tab->getClass() ?? '') ? 'notloaded' : '') ?>
         <?php $_tabType = (!preg_match('/\s?ajax\s?/', $_tabClass) && $block->getTabUrl($_tab) != '#') ? 'link' : '' ?>
         <?php $_tabHref = $block->getTabUrl($_tab) == '#' ?
             '#' . $tabId . '_content' :

app/code/Magento/Catalog/Model/ResourceModel/Product/Collection/ProductLimitation.php

@@ -35,6 +35,7 @@ class ProductLimitation implements \ArrayAccess
      * @return bool
      * @since 101.0.0
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return array_key_exists($offset, $this->productLimitationFilters);
@@ -45,6 +46,7 @@ public function offsetExists($offset)
      * @return mixed
      * @since 101.0.0
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return $this->productLimitationFilters[$offset];
@@ -56,6 +58,7 @@ public function offsetGet($offset)
      * @return void
      * @since 101.0.0
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         $this->productLimitationFilters[$offset] = $value;
@@ -66,6 +69,7 @@ public function offsetSet($offset, $value)
      * @return void
      * @since 101.0.0
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->productLimitationFilters[$offset]);

app/code/Magento/Config/Model/Config/Structure/Element/Iterator.php

@@ -69,6 +69,7 @@ public function setElements(array $elements, $scope)
      *
      * @return \Magento\Config\Model\Config\StructureElementInterface
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         return $this->_flyweight;
@@ -79,6 +80,7 @@ public function current()
      *
      * @return void Any returned value is ignored.
      */
+    #[\ReturnTypeWillChange]
     public function next()
     {
         next($this->_elements);
@@ -106,6 +108,7 @@ protected function _initFlyweight(array $element)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function key()
     {
         key($this->_elements);
@@ -117,6 +120,7 @@ public function key()
      * @return bool The return value will be casted to boolean and then evaluated.
      * Returns true on success or false on failure.
      */
+    #[\ReturnTypeWillChange]
     public function valid()
     {
         return (bool)current($this->_elements);
@@ -127,6 +131,7 @@ public function valid()
      *
      * @return void Any returned value is ignored.
      */
+    #[\ReturnTypeWillChange]
     public function rewind()
     {
         reset($this->_elements);

app/code/Magento/Customer/Model/Indexer/Source.php

@@ -82,6 +82,7 @@ public function addFieldToFilter($attribute, $condition = null)
     /**
      * @inheritdoc
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         return $this->customerCollection->getSize();
@@ -92,6 +93,7 @@ public function count()
      *
      * @return Traversable
      */
+    #[\ReturnTypeWillChange]
     public function getIterator()
     {
         $this->customerCollection->setPageSize($this->batchSize);

app/code/Magento/Customer/Ui/Component/MassAction/Group/Options.php

@@ -81,6 +81,7 @@ public function __construct(
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
         if ($this->options === null) {

app/code/Magento/Eav/Model/Entity/Type.php

@@ -303,7 +303,7 @@ public function getValueTablePrefix()
      */
     public function getEntityTablePrefix()
     {
-        $tablePrefix = trim($this->_data['value_table_prefix']);
+        $tablePrefix = trim((string) $this->_data['value_table_prefix']);
 
         if (empty($tablePrefix)) {
             $tablePrefix = $this->getEntityTable();

app/code/Magento/ImportExport/Model/Import/AbstractSource.php

@@ -83,6 +83,7 @@ public function getColNames()
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         $row = $this->_row;
@@ -101,6 +102,7 @@ public function current()
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function next()
     {
         $this->_key++;
@@ -127,6 +129,7 @@ abstract protected function _getNextRow();
      *
      * @return int -1 if out of bounds, 0 or more otherwise
      */
+    #[\ReturnTypeWillChange]
     public function key()
     {
         return $this->_key;
@@ -137,6 +140,7 @@ public function key()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function valid()
     {
         return -1 !== $this->_key;
@@ -147,6 +151,7 @@ public function valid()
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function rewind()
     {
         $this->_key = -1;
@@ -161,6 +166,7 @@ public function rewind()
      * @return void
      * @throws \OutOfBoundsException
      */
+    #[\ReturnTypeWillChange]
     public function seek($position)
     {
         if ($position == $this->_key) {

app/code/Magento/ImportExport/Model/ResourceModel/Import/Data.php

@@ -56,6 +56,7 @@ protected function _construct()
      *
      * @return \Iterator
      */
+    #[\ReturnTypeWillChange]
     public function getIterator()
     {
         $connection = $this->getConnection();

app/code/Magento/Security/Observer/AdminUserAuthenticateBefore.php

@@ -56,7 +56,7 @@ public function execute(Observer $observer)
         /** @var \Magento\User\Model\User $user */
         $user->loadByUsername($username);
 
-        if ($user->getId() && $this->userExpirationManager->isUserExpired($user->getId())) {
+        if ($user->getId() && $this->userExpirationManager->isUserExpired((string) $user->getId())) {
             $this->userExpirationManager->deactivateExpiredUsersById([$user->getId()]);
             throw new AuthenticationException(
                 __(

app/code/Magento/Shipping/Model/Simplexml/Element.php

@@ -20,7 +20,7 @@ class Element extends \Magento\Framework\Simplexml\Element
      * @param string $namespace If specified, the namespace to which the attribute belongs.
      * @return void
      */
-    public function addAttribute($name, $value = null, $namespace = null)
+    public function addAttribute($name, $value = null, $namespace = null): void
     {
         $value = $value !== null ? $this->xmlentities($value) : '';
         parent::addAttribute($name, $value, $namespace);
@@ -34,7 +34,7 @@ public function addAttribute($name, $value = null, $namespace = null)
      * @param string $namespace If specified, the namespace to which the child element belongs.
      * @return \Magento\Shipping\Model\Simplexml\Element
      */
-    public function addChild($name, $value = null, $namespace = null)
+    public function addChild($name, $value = null, $namespace = null): self
     {
         if ($value !== null) {
             $value = $this->xmlentities($value);

app/code/Magento/Ui/DataProvider/AbstractDataProvider.php

@@ -267,6 +267,7 @@ public function getData()
      *
      * @return int
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         return $this->getCollection()->count();

app/code/Magento/Ui/Model/Export/SearchResultIterator.php

@@ -24,6 +24,7 @@ public function __construct(
     /**
      * @return array|mixed
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         return current($this->items);
@@ -32,6 +33,7 @@ public function current()
     /**
      * @return int|mixed
      */
+    #[\ReturnTypeWillChange]
     public function key()
     {
         return key($this->items);
@@ -40,6 +42,7 @@ public function key()
     /**
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function next()
     {
         next($this->items);
@@ -48,6 +51,7 @@ public function next()
     /**
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function rewind()
     {
         reset($this->items);
@@ -56,6 +60,7 @@ public function rewind()
     /**
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function valid()
     {
         return $this->key() !== null;

lib/internal/Magento/Framework/Api/Search/Document.php

@@ -70,6 +70,7 @@ public function setCustomAttributes(array $attributes)
      * @return \ArrayIterator
      * @since 100.1.0
      */
+    #[\ReturnTypeWillChange]
     public function getIterator()
     {
         $attributes = (array)$this->getCustomAttributes();

lib/internal/Magento/Framework/App/Cache/Frontend/Pool.php

@@ -97,6 +97,7 @@ protected function _getCacheSettings()
      *
      * @return \Magento\Framework\Cache\FrontendInterface
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         $this->_initialize();
@@ -106,6 +107,7 @@ public function current()
     /**
      * @inheritdoc
      */
+    #[\ReturnTypeWillChange]
     public function key()
     {
         $this->_initialize();
@@ -115,6 +117,7 @@ public function key()
     /**
      * @inheritdoc
      */
+    #[\ReturnTypeWillChange]
     public function next()
     {
         $this->_initialize();
@@ -124,6 +127,7 @@ public function next()
     /**
      * @inheritdoc
      */
+    #[\ReturnTypeWillChange]
     public function rewind()
     {
         $this->_initialize();
@@ -133,6 +137,7 @@ public function rewind()
     /**
      * @inheritdoc
      */
+    #[\ReturnTypeWillChange]
     public function valid()
     {
         $this->_initialize();

lib/internal/Magento/Framework/App/RouterList.php

@@ -60,6 +60,7 @@ protected function getRouterInstance($routerId)
      * @link http://php.net/manual/en/iterator.current.php
      * @return RouterInterface
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         return $this->getRouterInstance($this->key());
@@ -71,6 +72,7 @@ public function current()
      * @link http://php.net/manual/en/iterator.next.php
      * @return void Any returned value is ignored.
      */
+    #[\ReturnTypeWillChange]
     public function next()
     {
         next($this->routerList);
@@ -82,6 +84,7 @@ public function next()
      * @link http://php.net/manual/en/iterator.key.php
      * @return string|int|null
      */
+    #[\ReturnTypeWillChange]
     public function key()
     {
         return key($this->routerList);
@@ -94,6 +97,7 @@ public function key()
      * @return boolean The return value will be casted to boolean and then evaluated.
      * Returns true on success or false on failure.
      */
+    #[\ReturnTypeWillChange]
     public function valid()
     {
         return !!current($this->routerList);
@@ -105,6 +109,7 @@ public function valid()
      * @link http://php.net/manual/en/iterator.rewind.php
      * @return void Any returned value is ignored.
      */
+    #[\ReturnTypeWillChange]
     public function rewind()
     {
         reset($this->routerList);