Use one format in all places for array_merge

app/code/Magento/Catalog/Block/Product/ListProduct.php

@@ -367,7 +367,7 @@ public function getIdentities()
                 $identities[] = $item->getIdentities();
             }
         }
-        $identities = array_merge(...$identities);
+        $identities = array_merge([], ...$identities);
 
         return $identities;
     }

app/code/Magento/Catalog/Block/Product/ProductList/Related.php

@@ -143,11 +143,11 @@ public function getItems()
      */
     public function getIdentities()
     {
-        $identities = [[]];
+        $identities = [];
         foreach ($this->getItems() as $item) {
             $identities[] = $item->getIdentities();
         }
-        return array_merge(...$identities);
+        return array_merge([], ...$identities);
     }
 
     /**

app/code/Magento/Catalog/Block/Product/ProductList/Upsell.php

@@ -267,10 +267,10 @@ public function getItemLimit($type = '')
      */
     public function getIdentities()
     {
-        $identities = array_map(function (DataObject $item) {
-            return $item->getIdentities();
-        }, $this->getItems()) ?: [[]];
-
-        return array_merge(...$identities);
+        $identities = [];
+        foreach ($this->getItems() as $item) {
+            $identities[] = $item->getIdentities();
+        }
+        return array_merge([], ...$identities);
     }
 }

app/code/Magento/Catalog/Model/Indexer/Product/Category/Action/Rows.php

@@ -270,14 +270,14 @@ private function getCategoryIdsFromIndex(array $productIds): array
             );
             $categoryIds[] = $storeCategories;
         }
-        $categoryIds = array_merge(...$categoryIds);
+        $categoryIds = array_merge([], ...$categoryIds);
 
         $parentCategories = [$categoryIds];
         foreach ($categoryIds as $categoryId) {
             $parentIds = explode('/', $this->getPathFromCategoryId($categoryId));
             $parentCategories[] = $parentIds;
         }
-        $categoryIds = array_unique(array_merge(...$parentCategories));
+        $categoryIds = array_unique(array_merge([], ...$parentCategories));
 
         return $categoryIds;
     }

app/code/Magento/Catalog/Model/Indexer/Product/Flat/FlatTableBuilder.php

@@ -261,7 +261,7 @@ protected function _fillTemporaryFlatTable(array $tables, $storeId, $valueFieldS
 
         $select->from(
             ['et' => $entityTemporaryTableName],
-            array_merge(...$allColumns)
+            array_merge([], ...$allColumns)
         )->joinInner(
             ['e' => $this->resource->getTableName('catalog_product_entity')],
             'e.entity_id = et.entity_id',
@@ -306,7 +306,7 @@ protected function _fillTemporaryFlatTable(array $tables, $storeId, $valueFieldS
                 $allColumns[] = $columnValueNames;
             }
         }
-        $sql = $select->insertFromSelect($temporaryFlatTableName, array_merge(...$allColumns), false);
+        $sql = $select->insertFromSelect($temporaryFlatTableName, array_merge([], ...$allColumns), false);
         $this->_connection->query($sql);
     }
 

app/code/Magento/Catalog/Model/Product.php

@@ -835,10 +835,7 @@ public function getStoreIds()
                     $storeIds[] = $websiteStores;
                 }
             }
-            if ($storeIds) {
-                $storeIds = array_merge(...$storeIds);
-            }
-            $this->setStoreIds($storeIds);
+            $this->setStoreIds(array_merge([], ...$storeIds));
         }
         return $this->getData('store_ids');
     }
@@ -1033,7 +1030,7 @@ public function priceReindexCallback()
      */
     public function eavReindexCallback()
     {
-        if ($this->isObjectNew() || $this->isDataChanged($this)) {
+        if ($this->isObjectNew() || $this->isDataChanged()) {
             $this->_productEavIndexerProcessor->reindexRow($this->getEntityId());
         }
     }
@@ -1179,7 +1176,7 @@ public function getTierPrice($qty = null)
     /**
      * Get formatted by currency product price
      *
-     * @return  array|double
+     * @return array|double
      * @since 102.0.6
      */
     public function getFormattedPrice()

app/code/Magento/Catalog/Model/Product/Price/TierPriceStorage.php

@@ -12,9 +12,6 @@
 use Magento\Catalog\Model\Product\Price\Validation\TierPriceValidator;
 use Magento\Catalog\Model\ProductIdLocatorInterface;
 
-/**
- * Tier price storage.
- */
 class TierPriceStorage implements TierPriceStorageInterface
 {
     /**
@@ -220,7 +217,7 @@ private function retrieveAffectedIds(array $skus): array
             $affectedIds[] = array_keys($productId);
         }
 
-        return $affectedIds ? array_unique(array_merge(...$affectedIds)) : [];
+        return array_unique(array_merge([], ...$affectedIds));
     }
 
     /**

app/code/Magento/Catalog/Model/ProductLink/ProductLinkQuery.php

@@ -103,7 +103,7 @@ private function extractRequestedLinkTypes(array $criteria): array
             if (count($linkTypesToLoad) === 1) {
                 $linkTypesToLoad = $linkTypesToLoad[0];
             } else {
-                $linkTypesToLoad = array_merge(...$linkTypesToLoad);
+                $linkTypesToLoad = array_merge([], ...$linkTypesToLoad);
             }
             $linkTypesToLoad = array_flip($linkTypesToLoad);
             $linkTypes = array_filter(

app/code/Magento/Catalog/Model/ResourceModel/Product/LinkedProductSelectBuilderComposite.php

@@ -33,7 +33,7 @@ public function build(int $productId, int $storeId) : array
         foreach ($this->linkedProductSelectBuilder as $productSelectBuilder) {
             $selects[] = $productSelectBuilder->build($productId, $storeId);
         }
-        $selects = array_merge(...$selects);
+        $selects = array_merge([], ...$selects);
 
         return $selects;
     }

app/code/Magento/CatalogGraphQl/DataProvider/Product/LayeredNavigation/Builder/Attribute.php

@@ -155,6 +155,10 @@ function (AggregationValueInterface $value) {
             return [];
         }
 
-        return $this->attributeOptionProvider->getOptions(\array_merge(...$attributeOptionIds), $storeId, $attributes);
+        return $this->attributeOptionProvider->getOptions(
+            \array_merge([], ...$attributeOptionIds),
+            $storeId,
+            $attributes
+        );
     }
 }

app/code/Magento/CatalogGraphQl/DataProvider/Product/LayeredNavigation/LayerBuilder.php

@@ -36,7 +36,7 @@ public function build(AggregationInterface $aggregation, ?int $storeId): array
         foreach ($this->builders as $builder) {
             $layers[] = $builder->build($aggregation, $storeId);
         }
-        $layers = \array_merge(...$layers);
+        $layers = \array_merge([], ...$layers);
 
         return \array_filter($layers);
     }

app/code/Magento/CatalogGraphQl/Model/AttributesJoiner.php

@@ -88,7 +88,7 @@ public function getQueryFields(FieldNode $fieldNode, ResolveInfo $resolveInfo):
                 }
             }
             if ($fragmentFields) {
-                $selectedFields = array_merge($selectedFields, array_merge(...$fragmentFields));
+                $selectedFields = array_merge([], $selectedFields, ...$fragmentFields);
             }
             $this->setSelectionsForFieldNode($fieldNode, array_unique($selectedFields));
         }

app/code/Magento/CatalogGraphQl/Model/Resolver/Products/SearchCriteria/CollectionProcessor/FilterProcessor/CategoryFilter.php

@@ -64,7 +64,7 @@ public function apply(Filter $filter, AbstractDb $collection)
             $collection->addCategoryFilter($category);
         }
 
-        $categoryProductIds = array_unique(array_merge(...$categoryProducts));
+        $categoryProductIds = array_unique(array_merge([], ...$categoryProducts));
         $collection->addIdFilter($categoryProductIds);
         return true;
     }

app/code/Magento/CatalogInventory/Model/StockIndex.php

@@ -169,11 +169,11 @@ protected function processChildren(
 
         $requiredChildrenIds = $typeInstance->getChildrenIds($productId, true);
         if ($requiredChildrenIds) {
-            $childrenIds = [[]];
+            $childrenIds = [];
             foreach ($requiredChildrenIds as $groupedChildrenIds) {
                 $childrenIds[] = $groupedChildrenIds;
             }
-            $childrenIds = array_merge(...$childrenIds);
+            $childrenIds = array_merge([], ...$childrenIds);
 
             $childrenWebsites = $this->productWebsite->getWebsites($childrenIds);
             foreach ($websitesWithStores as $websiteId => $storeId) {
@@ -232,13 +232,13 @@ protected function getWebsitesWithDefaultStores($websiteId = null)
      */
     protected function processParents($productId, $websiteId)
     {
-        $parentIds = [[]];
+        $parentIds = [];
         foreach ($this->getProductTypeInstances() as $typeInstance) {
             /* @var ProductType\AbstractType $typeInstance */
             $parentIds[] = $typeInstance->getParentIdsByChild($productId);
         }
 
-        $parentIds = array_merge(...$parentIds);
+        $parentIds = array_merge([], ...$parentIds);
 
         if (empty($parentIds)) {
             return;

app/code/Magento/CatalogSearch/Model/Layer/Filter/Attribute.php

@@ -70,7 +70,7 @@ public function apply(\Magento\Framework\App\RequestInterface $request)
             $label = $this->getOptionText($value);
             $labels[] = is_array($label) ? $label : [$label];
         }
-        $label = implode(',', array_unique(array_merge(...$labels)));
+        $label = implode(',', array_unique(array_merge([], ...$labels)));
         $this->getLayer()
             ->getState()
             ->addFilter($this->_createItem($label, $attributeValue));

app/code/Magento/CatalogUrlRewrite/Model/Category/Plugin/Store/Group.php

@@ -121,7 +121,7 @@ public function afterSave(
      */
     protected function generateProductUrls($websiteId, $originWebsiteId)
     {
-        $urls = [[]];
+        $urls = [];
         $websiteIds = $websiteId != $originWebsiteId
             ? [$websiteId, $originWebsiteId]
             : [$websiteId];
@@ -136,7 +136,7 @@ protected function generateProductUrls($websiteId, $originWebsiteId)
             $urls[] = $this->productUrlRewriteGenerator->generate($product);
         }
 
-        return array_merge(...$urls);
+        return array_merge([], ...$urls);
     }
 
     /**
@@ -148,7 +148,7 @@ protected function generateProductUrls($websiteId, $originWebsiteId)
      */
     protected function generateCategoryUrls($rootCategoryId, $storeIds)
     {
-        $urls = [[]];
+        $urls = [];
         $categories = $this->categoryFactory->create()->getCategories($rootCategoryId, 1, false, true);
         foreach ($categories as $category) {
             /** @var \Magento\Catalog\Model\Category $category */
@@ -157,6 +157,6 @@ protected function generateCategoryUrls($rootCategoryId, $storeIds)
             $urls[] = $this->categoryUrlRewriteGenerator->generate($category);
         }
 
-        return array_merge(...$urls);
+        return array_merge([], ...$urls);
     }
 }

app/code/Magento/CatalogUrlRewrite/Observer/AfterImportDataObserver.php

@@ -37,8 +37,6 @@
 use RuntimeException;
 
 /**
- * Class AfterImportDataObserver
- *
  * @SuppressWarnings(PHPMD.TooManyFields)
  * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
  */
@@ -459,8 +457,7 @@ private function categoriesUrlRewriteGenerate(): array
                 }
             }
         }
-        $result = !empty($urls) ? array_merge(...$urls) : [];
-        return $result;
+        return array_merge([], ...$urls);
     }
 
     /**

app/code/Magento/CatalogWidget/Block/Product/ProductsList.php

@@ -506,15 +506,15 @@ public function getPagerHtml()
      */
     public function getIdentities()
     {
-        $identities = [[]];
+        $identities = [];
         if ($this->getProductCollection()) {
             foreach ($this->getProductCollection() as $product) {
                 if ($product instanceof IdentityInterface) {
                     $identities[] = $product->getIdentities();
                 }
             }
         }
-        $identities = array_merge(...$identities);
+        $identities = array_merge([], ...$identities);
 
         return $identities ?: [Product::CACHE_TAG];
     }

app/code/Magento/CheckoutAgreements/Model/AgreementsValidator.php

@@ -35,12 +35,12 @@ public function __construct($list = null)
     public function isValid($agreementIds = [])
     {
         $agreementIds = $agreementIds === null ? [] : $agreementIds;
-        $requiredAgreements = [[]];
+        $requiredAgreements = [];
         foreach ($this->agreementsProviders as $agreementsProvider) {
             $requiredAgreements[] = $agreementsProvider->getRequiredAgreementIds();
         }
 
-        $agreementsDiff = array_diff(array_merge(...$requiredAgreements), $agreementIds);
+        $agreementsDiff = array_diff(array_merge([], ...$requiredAgreements), $agreementIds);
 
         return empty($agreementsDiff);
     }

app/code/Magento/Cms/view/adminhtml/templates/browser/content/uploader.phtml

@@ -11,14 +11,14 @@ $filters = $block->getConfig()->getFilters() ?? [];
 $allowedExtensions = [];
 $blockHtmlId = $block->getHtmlId();
 
-$listExtensions = [[]];
+$listExtensions = [];
 foreach ($filters as $media_type) {
     $listExtensions[] = array_map(function ($fileExt) {
         return ltrim($fileExt, '.*');
     }, $media_type['files']);
 }
 
-$allowedExtensions = array_merge(...$listExtensions);
+$allowedExtensions = array_merge([], ...$listExtensions);
 
 $resizeConfig = $block->getImageUploadConfigData()->getIsResizeEnabled()
     ? "{action: 'resize', maxWidth: "

app/code/Magento/Csp/Helper/InlineUtil.php

@@ -110,14 +110,14 @@ private function extractHost(string $url): ?string
      */
     private function extractRemoteFonts(string $styleContent): array
     {
-        $urlsFound = [[]];
+        $urlsFound = [];
         preg_match_all('/\@font\-face\s*?\{([^\}]*)[^\}]*?\}/im', $styleContent, $fontFaces);
         foreach ($fontFaces[1] as $fontFaceContent) {
             preg_match_all('/url\([\'\"]?(http(s)?\:[^\)]+)[\'\"]?\)/i', $fontFaceContent, $urls);
             $urlsFound[] = $urls[1];
         }
 
-        return array_map([$this, 'extractHost'], array_merge(...$urlsFound));
+        return array_map([$this, 'extractHost'], array_merge([], ...$urlsFound));
     }
 
     /**

app/code/Magento/CurrencySymbol/Model/System/Currencysymbol.php

@@ -292,7 +292,7 @@ protected function _unserializeStoreConfig($configPath, $storeId = null)
      */
     protected function getAllowedCurrencies()
     {
-        $allowedCurrencies = [[]];
+        $allowedCurrencies = [];
         $allowedCurrencies[] = explode(
             self::ALLOWED_CURRENCIES_CONFIG_SEPARATOR,
             $this->_scopeConfig->getValue(
@@ -330,6 +330,6 @@ protected function getAllowedCurrencies()
                 }
             }
         }
-        return array_unique(array_merge(...$allowedCurrencies));
+        return array_unique(array_merge([], ...$allowedCurrencies));
     }
 }

app/code/Magento/Customer/Model/Address/CompositeValidator.php

@@ -30,11 +30,11 @@ public function __construct(
      */
     public function validate(AbstractAddress $address)
     {
-        $errors = [[]];
+        $errors = [];
         foreach ($this->validators as $validator) {
             $errors[] = $validator->validate($address);
         }
 
-        return array_merge(...$errors);
+        return array_merge([], ...$errors);
     }
 }

app/code/Magento/Customer/Model/Metadata/Form.php

@@ -363,11 +363,11 @@ public function validateData(array $data)
     {
         $validator = $this->_getValidator($data);
         if (!$validator->isValid(false)) {
-            $messages = [[]];
+            $messages = [];
             foreach ($validator->getMessages() as $errorMessages) {
                 $messages[] = (array)$errorMessages;
             }
-            return array_merge(...$messages);
+            return array_merge([], ...$messages);
         }
         return true;
     }