diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index fa38bfb..5305248 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -1286,7 +1286,6 @@ function comment_get_display_page($cid, $instance) {
  * @param \Drupal\comment\CommentInterface $comment
  */
 function comment_preview(CommentInterface $comment) {
-  global $user;
   $preview_build = array();
   $entity = entity_load($comment->entity_type->value, $comment->entity_id->value);
 
@@ -1295,8 +1294,8 @@ function comment_preview(CommentInterface $comment) {
     if (!empty($comment->name->value)) {
       $account = user_load_by_name($comment->name->value);
     }
-    elseif ($user->isAuthenticated() && empty($comment->is_anonymous)) {
-      $account = $user;
+    elseif (\Drupal::currentUser()->isAuthenticated() && empty($comment->is_anonymous)) {
+      $account = \Drupal::currentUser();
     }
 
     if (!empty($account) && $account->isAuthenticated()) {
@@ -1524,13 +1523,12 @@ function template_preprocess_comment(&$variables) {
 function theme_comment_post_forbidden($variables) {
   $entity = $variables['commented_entity'];
   $field_name = $variables['field_name'];
-  global $user;
 
   // Since this is expensive to compute, we cache it so that a page with many
   // comments only has to query the database once for all the links.
   $authenticated_post_comments = &drupal_static(__FUNCTION__, NULL);
 
-  if ($user->isAnonymous()) {
+  if (\Drupal::currentUser()->isAnonymous()) {
     if (!isset($authenticated_post_comments)) {
       // We only output a link if we are certain that users will get permission
       // to post comments by logging in.
diff --git a/core/modules/comment/lib/Drupal/comment/Entity/Comment.php b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
index cf96a59..37cefc2 100644
--- a/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
+++ b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
@@ -216,10 +216,8 @@ public function id() {
   public function preSave(EntityStorageControllerInterface $storage_controller) {
     parent::preSave($storage_controller);
 
-    $user = \Drupal::currentUser();
-
     if (!isset($this->status->value)) {
-      $this->status->value = $user->hasPermission('skip comment approval') ? COMMENT_PUBLISHED : COMMENT_NOT_PUBLISHED;
+      $this->status->value = \Drupal::currentUser()->hasPermission('skip comment approval') ? COMMENT_PUBLISHED : COMMENT_NOT_PUBLISHED;
     }
     if ($this->isNew()) {
       // Add the comment to database. This next section builds the thread field.
@@ -288,8 +286,8 @@ public function preSave(EntityStorageControllerInterface $storage_controller) {
       }
       // We test the value with '===' because we need to modify anonymous
       // users as well.
-      if ($this->uid->target_id === $user->id() && $user->isAuthenticated()) {
-        $this->name->value = $user->getUsername();
+      if ($this->uid->target_id === \Drupal::currentUser()->id() && \Drupal::currentUser()->isAuthenticated()) {
+        $this->name->value = \Drupal::currentUser()->getUsername();
       }
       // Add the values which aren't passed into the function.
       $this->thread->value = $thread;
diff --git a/core/modules/comment/lib/Drupal/comment/Plugin/views/field/NodeNewComments.php b/core/modules/comment/lib/Drupal/comment/Plugin/views/field/NodeNewComments.php
index 3e36dff..b12ade0 100644
--- a/core/modules/comment/lib/Drupal/comment/Plugin/views/field/NodeNewComments.php
+++ b/core/modules/comment/lib/Drupal/comment/Plugin/views/field/NodeNewComments.php
@@ -93,7 +93,7 @@ public function query() {
   }
 
   public function preRender(&$values) {
-    global $user;
+    $user = \Drupal::currentUser();
     if ($user->isAnonymous() || empty($values)) {
       return;
     }
diff --git a/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationController.php b/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationController.php
index 634043b..18192c6 100644
--- a/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationController.php
+++ b/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationController.php
@@ -237,7 +237,7 @@ public function entityFormAlter(array &$form, array &$form_state, EntityInterfac
       // Default to the anonymous user.
       $name = '';
       if ($new_translation) {
-        $name = $GLOBALS['user']->getUsername();
+        $name = \Drupal::currentUser()->getUsername();
       }
       elseif ($entity->translation[$form_langcode]['uid']) {
         $name = user_load($entity->translation[$form_langcode]['uid'])->getUsername();