Issue #3266568 by mxr576, sourabhjain, quietone: Refactor array_merge() usage in loops as possible for performance

core/lib/Drupal/Core/Authentication/AuthenticationCollector.php

@@ -72,7 +72,7 @@ class AuthenticationCollector implements AuthenticationCollectorInterface {
       krsort($this->providerOrders);
 
       // Merge nested providers from $this->providers into $this->sortedProviders.
-      $this->sortedProviders = array_merge([], ...$this->providerOrders);
+      $this->sortedProviders = array_merge(...$this->providerOrders);
     }
 
     return $this->sortedProviders;

core/lib/Drupal/Core/Breadcrumb/BreadcrumbManager.php

@@ -107,7 +107,7 @@ class BreadcrumbManager implements ChainBreadcrumbBuilderInterface {
       // Sort the builders according to priority.
       krsort($this->builders);
       // Merge nested builders from $this->builders into $this->sortedBuilders.
-      $this->sortedBuilders = array_merge([], ...$this->builders);
+      $this->sortedBuilders = array_merge(...$this->builders);
     }
     return $this->sortedBuilders;
   }

core/lib/Drupal/Core/Config/ConfigManager.php

@@ -264,7 +264,7 @@ class ConfigManager implements ConfigManagerInterface {
     foreach ($names as $name) {
       $dependencies[] = $dependency_manager->getDependentEntities($type, $name);
     }
-    return array_merge([], ...$dependencies);
+    return array_merge(...$dependencies);
   }
 
   /**
@@ -292,9 +292,9 @@ class ConfigManager implements ConfigManagerInterface {
       $storage = $this->entityTypeManager->getStorage($entity_type_id);
       // Remove the keys since there are potential ID clashes from different
       // configuration entity types.
-      $entities_to_return = array_merge($entities_to_return, array_values($storage->loadMultiple($entities_to_load)));
+      $entities_to_return[] = array_values($storage->loadMultiple($entities_to_load));
     }
-    return $entities_to_return;
+    return array_merge(...$entities_to_return);
   }
 
   /**
@@ -487,13 +487,14 @@ class ConfigManager implements ConfigManagerInterface {
     $missing_dependencies = [];
     foreach ($this->activeStorage->readMultiple($this->activeStorage->listAll()) as $config_data) {
       if (isset($config_data['dependencies']['content'])) {
-        $content_dependencies = array_merge($content_dependencies, $config_data['dependencies']['content']);
+        $content_dependencies[] = $config_data['dependencies']['content'];
       }
       if (isset($config_data['dependencies']['enforced']['content'])) {
-        $content_dependencies = array_merge($content_dependencies, $config_data['dependencies']['enforced']['content']);
+        $content_dependencies[] = $config_data['dependencies']['enforced']['content'];
       }
     }
-    foreach (array_unique($content_dependencies) as $content_dependency) {
+    $unique_content_dependencies = array_unique(array_merge(...$content_dependencies));
+    foreach ($unique_content_dependencies as $content_dependency) {
       // Format of the dependency is entity_type:bundle:uuid.
       [$entity_type, $bundle, $uuid] = explode(':', $content_dependency, 3);
       if (!$this->entityRepository->loadEntityByUuid($entity_type, $uuid)) {

core/lib/Drupal/Core/Config/Entity/Query/Query.php

@@ -129,7 +129,8 @@ class Query extends QueryBase implements QueryInterface {
     $prefix_length = strlen($prefix);
 
     // Search the conditions for restrictions on configuration object names.
-    $names = FALSE;
+    $filter_by_names = [];
+    $has_added_restrictions = FALSE;
     $id_condition = NULL;
     $id_key = $this->entityType->getKey('id');
     if ($this->condition->getConjunction() == 'AND') {
@@ -140,21 +141,22 @@ class Query extends QueryBase implements QueryInterface {
         if (is_string($condition['field']) && ($operator == 'IN' || $operator == '=')) {
           // Special case ID lookups.
           if ($condition['field'] == $id_key) {
+            $has_added_restrictions = TRUE;
             $ids = (array) $condition['value'];
-            $names = array_map(function ($id) use ($prefix) {
+            $filter_by_names[] = array_map(static function ($id) use ($prefix) {
               return $prefix . $id;
             }, $ids);
           }
           elseif (in_array($condition['field'], $lookup_keys)) {
+            $has_added_restrictions = TRUE;
             // If we don't find anything then there are no matches. No point in
             // listing anything.
-            $names = [];
             $keys = (array) $condition['value'];
-            $keys = array_map(function ($value) use ($condition) {
+            $keys = array_map(static function ($value) use ($condition) {
               return $condition['field'] . ':' . $value;
             }, $keys);
             foreach ($this->getConfigKeyStore()->getMultiple($keys) as $list) {
-              $names = array_merge($names, $list);
+              $filter_by_names[] = $list;
             }
           }
         }
@@ -166,7 +168,7 @@ class Query extends QueryBase implements QueryInterface {
         // We stop at the first restricting condition on name. In the case where
         // there are additional restricting conditions, results will be
         // eliminated when the conditions are checked on the loaded records.
-        if ($names !== FALSE) {
+        if ($has_added_restrictions !== FALSE) {
           // If the condition has been responsible for narrowing the list of
           // configuration to check there is no point in checking it further.
           unset($conditions[$condition_key]);
@@ -174,52 +176,56 @@ class Query extends QueryBase implements QueryInterface {
         }
       }
     }
+
     // If no restrictions on IDs were found, we need to parse all records.
-    if ($names === FALSE) {
+    if ($has_added_restrictions === FALSE) {
-      $names = $this->configFactory->listAll($prefix);
+      $filter_by_names = $this->configFactory->listAll($prefix);
+    }
+    else {
+      $filter_by_names = array_merge(...$filter_by_names);
     }
     // In case we have an ID condition, try to narrow down the list of config
     // objects to load.
-    if ($id_condition && !empty($names)) {
+    if ($id_condition && !empty($filter_by_names)) {
       $value = $id_condition['value'];
       $filter = NULL;
       switch ($id_condition['operator']) {
         case '<>':
-          $filter = function ($name) use ($value, $prefix_length) {
+          $filter = static function ($name) use ($value, $prefix_length) {
             $id = substr($name, $prefix_length);
             return $id !== $value;
           };
           break;
 
         case 'STARTS_WITH':
-          $filter = function ($name) use ($value, $prefix_length) {
+          $filter = static function ($name) use ($value, $prefix_length) {
             $id = substr($name, $prefix_length);
             return strpos($id, $value) === 0;
           };
           break;
 
         case 'CONTAINS':
-          $filter = function ($name) use ($value, $prefix_length) {
+          $filter = static function ($name) use ($value, $prefix_length) {
             $id = substr($name, $prefix_length);
             return strpos($id, $value) !== FALSE;
           };
           break;
 
         case 'ENDS_WITH':
-          $filter = function ($name) use ($value, $prefix_length) {
+          $filter = static function ($name) use ($value, $prefix_length) {
             $id = substr($name, $prefix_length);
             return strrpos($id, $value) === strlen($id) - strlen($value);
           };
           break;
       }
       if ($filter) {
-        $names = array_filter($names, $filter);
+        $filter_by_names = array_filter($filter_by_names, $filter);
       }
     }
 
     // Load the corresponding records.
     $records = [];
-    foreach ($this->configFactory->loadMultiple($names) as $config) {
+    foreach ($this->configFactory->loadMultiple($filter_by_names) as $config) {
       $records[substr($config->getName(), $prefix_length)] = $config->get();
     }
     return $records;

core/lib/Drupal/Core/Config/PreExistingConfigException.php

@@ -88,9 +88,9 @@ class PreExistingConfigException extends ConfigException {
         }
         return $config_name;
       }, $config_names);
-      $flat_config_objects = array_merge($flat_config_objects, $config_names);
+      $flat_config_objects[] = $config_names;
     }
-    return $flat_config_objects;
+    return array_merge(...$flat_config_objects);
   }
 
 }

core/lib/Drupal/Core/Config/Schema/SchemaCheckTrait.php

@@ -56,7 +56,7 @@ trait SchemaCheckTrait {
     foreach ($config_data as $key => $value) {
       $errors[] = $this->checkValue($key, $value);
     }
-    $errors = array_merge([], ...$errors);
+    $errors = array_merge(...$errors);
     if (empty($errors)) {
       return TRUE;
     }

core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php

@@ -560,8 +560,9 @@ class SqlContentEntityStorage extends ContentEntityStorageBase implements SqlEnt
             // returns an array keyed by property names so remove the keys
             // before array_merge() to avoid losing data with fields having the
             // same columns i.e. value.
-            $column_names = array_merge($column_names, array_values($table_mapping->getColumnNames($data_field)));
+            $column_names[] = array_values($table_mapping->getColumnNames($data_field));
           }
+          $column_names = array_merge(...$column_names);
           $query->fields('data', $column_names);
         }
 

core/lib/Drupal/Core/Extension/ModuleHandler.php

@@ -499,7 +499,7 @@ class ModuleHandler implements ModuleHandlerInterface {
         foreach ($extra_types as $extra_type) {
           $extra_modules[] = array_keys($this->getImplementationInfo($extra_type . '_alter'));
         }
-        $extra_modules = array_merge([], ...$extra_modules);
+        $extra_modules = array_merge(...$extra_modules);
         // If any modules implement one of the extra hooks that do not implement
         // the primary hook, we need to add them to the $modules array in their
         // appropriate order. $this->getImplementationInfo() can only return

core/lib/Drupal/Core/File/FileSystem.php

@@ -700,7 +700,8 @@ class FileSystem implements FileSystemInterface {
    * @see \Drupal\Core\File\FileSystemInterface::scanDirectory()
    */
   protected function doScanDirectory($dir, $mask, array $options = [], $depth = 0) {
-    $files = [];
+    $files_in_sub_dirs = [];
+    $files_in_this_directory = [];
     // Avoid warnings when opendir does not have the permissions to open a
     // directory.
     if ($handle = @opendir($dir)) {
@@ -714,19 +715,17 @@ class FileSystem implements FileSystemInterface {
             $uri = "$dir/$filename";
           }
           if ($options['recurse'] && is_dir($uri)) {
-            // Give priority to files in this folder by merging them in after
+            $files_in_sub_dirs[] = $this->doScanDirectory($uri, $mask, $options, $depth + 1);
-            // any subdirectory files.
-            $files = array_merge($this->doScanDirectory($uri, $mask, $options, $depth + 1), $files);
           }
           elseif ($depth >= $options['min_depth'] && preg_match($mask, $filename)) {
-            // Always use this match over anything already set in $files with
+            // Always use this match over anything already set with the same
-            // the same $options['key'].
+            // $options['key'].
             $file = new \stdClass();
             $file->uri = $uri;
             $file->filename = $filename;
             $file->name = pathinfo($filename, PATHINFO_FILENAME);
             $key = $options['key'];
-            $files[$file->$key] = $file;
+            $files_in_this_directory[$file->$key] = $file;
             if ($options['callback']) {
               $options['callback']($uri);
             }
@@ -739,7 +738,9 @@ class FileSystem implements FileSystemInterface {
       $this->logger->error('@dir can not be opened', ['@dir' => $dir]);
     }
 
-    return $files;
+    // Give priority to files in this folder by merging them after
+    // any subdirectory files.
+    return array_merge(array_merge(...$files_in_sub_dirs), $files_in_this_directory);
   }
 
 }

core/lib/Drupal/Core/File/MimeType/MimeTypeGuesser.php

@@ -108,7 +108,7 @@ class MimeTypeGuesser implements MimeTypeGuesserInterface {
    */
   protected function sortGuessers() {
     krsort($this->guessers);
-    return array_merge([], ...$this->guessers);
+    return array_merge(...$this->guessers);
   }
 
 }

core/lib/Drupal/Core/Logger/LoggerChannel.php

@@ -166,7 +166,7 @@ class LoggerChannel implements LoggerChannelInterface {
    */
   protected function sortLoggers() {
     krsort($this->loggers);
-    return array_merge([], ...$this->loggers);
+    return array_merge(...$this->loggers);
   }
 
 }

core/lib/Drupal/Core/PathProcessor/PathProcessorManager.php

@@ -132,7 +132,7 @@ class PathProcessorManager implements InboundPathProcessorInterface, OutboundPat
    */
   protected function sortProcessors($type) {
     krsort($this->{$type});
-    return array_merge([], ...$this->{$type});
+    return array_merge(...$this->{$type});
   }
 
 }

core/lib/Drupal/Core/RouteProcessor/RouteProcessorManager.php

@@ -72,7 +72,7 @@ class RouteProcessorManager implements OutboundRouteProcessorInterface {
    */
   protected function sortProcessors() {
     krsort($this->outboundProcessors);
-    return array_merge([], ...$this->outboundProcessors);
+    return array_merge(...$this->outboundProcessors);
   }
 
 }

core/lib/Drupal/Core/Routing/MethodFilter.php

@@ -36,14 +36,14 @@ class MethodFilter implements FilterInterface {
       }
 
       if (!in_array($method, $supported_methods, TRUE)) {
-        $all_supported_methods = array_merge($supported_methods, $all_supported_methods);
+        $all_supported_methods[] = $supported_methods;
         $collection->remove($name);
       }
     }
     if (count($collection)) {
       return $collection;
     }
-    throw new MethodNotAllowedException(array_unique($all_supported_methods));
+    throw new MethodNotAllowedException(array_unique(array_merge(...$all_supported_methods)));
   }
 
 }

core/lib/Drupal/Core/StringTranslation/TranslationManager.php

@@ -78,7 +78,7 @@ class TranslationManager implements TranslationInterface, TranslatorInterface {
    */
   protected function sortTranslators() {
     krsort($this->translators);
-    return array_merge([], ...$this->translators);
+    return array_merge(...$this->translators);
   }
 
   /**

core/lib/Drupal/Core/Template/Attribute.php

@@ -183,8 +183,9 @@ class Attribute implements \ArrayAccess, \IteratorAggregate, MarkupInterface {
         // Merge the values passed in from the classes array.
         // The argument is cast to an array to support comma separated single
         // values or one or more array arguments.
-        $classes = array_merge($classes, (array) $arg);
+        $classes[] = (array) $arg;
       }
+      $classes = array_merge(...$classes);
 
       // Merge if there are values, just add them otherwise.
       if (isset($this->storage['class']) && $this->storage['class'] instanceof AttributeArray) {
@@ -271,8 +272,9 @@ class Attribute implements \ArrayAccess, \IteratorAggregate, MarkupInterface {
         // Merge the values passed in from the classes array.
         // The argument is cast to an array to support comma separated single
         // values or one or more array arguments.
-        $classes = array_merge($classes, (array) $arg);
+        $classes[] = (array) $arg;
       }
+      $classes = array_merge(...$classes);
 
       // Remove the values passed in from the value array. Use array_values() to
       // ensure that the array index remains sequential.

core/lib/Drupal/Core/Test/JUnitConverter.php

@@ -90,9 +90,9 @@ class JUnitConverter {
       if ($file && !$child->attributes()->file) {
         $child->addAttribute('file', $file);
       }
-      $test_cases = array_merge($test_cases, static::findTestCases($child, $element));
+      $test_cases[] = static::findTestCases($child, $element);
     }
-    return $test_cases;
+    return array_merge(...$test_cases);
   }
 
   /**

core/lib/Drupal/Core/Test/TestSetupTrait.php

@@ -195,12 +195,12 @@ trait TestSetupTrait {
     $exceptions = [];
     while ($class) {
       if (property_exists($class, 'configSchemaCheckerExclusions')) {
-        $exceptions = array_merge($exceptions, $class::$configSchemaCheckerExclusions);
+        $exceptions[] = $class::$configSchemaCheckerExclusions;
       }
       $class = get_parent_class($class);
     }
     // Filter out any duplicates.
-    return array_unique($exceptions);
+    return array_unique(array_merge(...$exceptions));
   }
 
 }

core/modules/config_translation/src/Controller/ConfigTranslationMapperList.php

@@ -71,7 +71,7 @@ class ConfigTranslationMapperList extends ControllerBase {
       $mappers[$weight] = $mapper;
     }
 
-    $build['#rows'] = array_merge([], ...$mappers);
+    $build['#rows'] = array_merge(...$mappers);
 
     return $build;
   }

core/modules/jsonapi/src/Routing/ReadOnlyModeMethodFilter.php

@@ -50,7 +50,7 @@ class ReadOnlyModeMethodFilter implements FilterInterface {
       $all_supported_methods[] = $route->getMethods();
     }
 
-    $all_supported_methods = array_merge([], ...$all_supported_methods);
+    $all_supported_methods = array_merge(...$all_supported_methods);
     $collection = $this->inner->filter($collection, $request);
 
     if (!$this->readOnlyModeIsEnabled) {

core/modules/locale/locale.bulk.inc

@@ -308,7 +308,7 @@ function locale_translate_batch_refresh(&$context) {
       foreach ($context['results']['stats'] as $report) {
         $strings[] = $report['strings'];
       }
-      $strings = array_merge([], ...$strings);
+      $strings = array_merge(...$strings);
     }
     if ($strings) {
       // Initialize multi-step string refresh.

core/modules/serialization/src/RegisterEntityResolversCompilerPass.php

@@ -49,7 +49,7 @@ class RegisterEntityResolversCompilerPass implements CompilerPassInterface {
    */
   protected function sort($services) {
     krsort($services);
-    return array_merge([], ...$services);
+    return array_merge(...$services);
   }
 
 }

core/modules/serialization/src/RegisterSerializationClassesCompilerPass.php

@@ -75,7 +75,7 @@ class RegisterSerializationClassesCompilerPass implements CompilerPassInterface
    */
   protected function sort($services) {
     krsort($services);
-    return array_merge([], ...$services);
+    return array_merge(...$services);
   }
 
 }

core/modules/views/src/Plugin/views/field/RenderedEntity.php

@@ -163,7 +163,7 @@ class RenderedEntity extends FieldPluginBase implements CacheableDependencyInter
     foreach ($view_displays as $view_display) {
       $tags[] = $view_display->getCacheTags();
     }
-    return array_merge([], ...$tags);
+    return array_merge(...$tags);
   }
 
   /**

core/modules/views/src/Plugin/views/query/Sql.php

@@ -1429,7 +1429,7 @@ class Sql extends QueryPluginBase {
    * Get the arguments attached to the WHERE and HAVING clauses of this query.
    */
   public function getWhereArgs() {
-    return array_merge([], ...array_column($this->where, 'args'), ...array_column($this->having, 'args'));
+    return array_merge(...array_column($this->where, 'args'), ...array_column($this->having, 'args'));
   }
 
   /**

core/tests/Drupal/Tests/Core/Authentication/AuthenticationCollectorTest.php

@@ -43,7 +43,7 @@ class AuthenticationCollectorTest extends UnitTestCase {
     krsort($providers);
 
     // Merge nested providers from $providers into $sorted_providers.
-    $sorted_providers = array_merge([], ...$providers);
+    $sorted_providers = array_merge(...$providers);
     $this->assertEquals($sorted_providers, $authentication_collector->getSortedProviders());
 
     // Test AuthenticationCollector::getProvider() and