Issue #2948211: Front page redirects break the canonical link

src/EventSubscriber/RouteNormalizerRequestSubscriber.php

@@ -31,6 +31,13 @@ class RouteNormalizerRequestSubscriber implements EventSubscriberInterface {
    */
   protected $config;
 
+  /**
+   * Global configuration.
+   *
+   * @var \Drupal\Core\Config\Config
+   */
+  protected $configMain;
+
   /**
    * The URL generator service.
    *
@@ -73,6 +80,7 @@ class RouteNormalizerRequestSubscriber implements EventSubscriberInterface {
     $this->pathMatcher = $path_matcher;
     $this->redirectChecker = $redirect_checker;
     $this->config = $config->get('redirect.settings');
+    $this->configMain = $config;
   }
 
   /**
@@ -103,7 +111,16 @@ class RouteNormalizerRequestSubscriber implements EventSubscriberInterface {
     if ($this->redirectChecker->canRedirect($request)) {
       // The "<current>" placeholder can be used for all routes except the front
       // page because it's not a real route.
-      $route_name = $this->pathMatcher->isFrontPage() ? '<front>' : '<current>';
+
+      $current_path = $this->currentPath->getPath();
+      $front_uri = $this->configMain->get('system.site')->get('page.front');
+      $front_alias = $this->aliasManager->getAliasByPath($front_uri);
+      $current_alias = $this->aliasManager->getAliasByPath($current_path);
+      $isFrontPage = $this->pathMatcher->isFrontPage() || $front_alias === $current_alias;
+      $route_name = '<current>';
+      if ($isFrontPage) {
+        $route_name = '<front>';
+      }
 
       // Explicitly replicate PathAliasSubscriber::onKernelController() to set
       // the cache key.