Issue #2822470 by Kazanir, Yogesh Pawar, markcarver, joelpittet, dawehner,...

Issue #2822470 by Kazanir, Yogesh Pawar, markcarver, joelpittet, dawehner, xjm, larowlan: Unified cache key & template class handling for Twig templates

core/core.services.yml

@@ -1618,7 +1618,10 @@ services:
       - { name: service_collector, tag: twig.loader, call: addLoader, required: TRUE }
   twig.loader.filesystem:
     class: Drupal\Core\Template\Loader\FilesystemLoader
-    arguments: ['@app.root', '@module_handler', '@theme_handler']
+    # We use '.' instead of '@app.root' as the path for non-namespaced template
+    # files so that they match the relative paths of templates loaded via the
+    # theme registry or via Twig namespaces.
+    arguments: ['.', '@module_handler', '@theme_handler']
     tags:
       - { name: twig.loader, priority: 100 }
   twig.loader.theme_registry:

core/tests/Drupal/KernelTests/Core/Theme/TwigEnvironmentTest.php

@@ -111,6 +111,35 @@ public function testTemplateNotFoundException() {
     }
   }
 
+  /**
+   * Ensures that templates resolve to the same class name and cache file.
+   */
+  public function testTemplateClassname() {
+    /** @var \Drupal\Core\Template\TwigEnvironment $environment */
+    $environment = \Drupal::service('twig');
+
+    // Test using an include template path.
+    $name_include = 'container.html.twig';
+    $class_include = $environment->getTemplateClass($name_include);
+    $key_include = $environment->getCache()->generateKey($name_include, $class_include);
+
+    // Test using a namespaced template path.
+    $name_namespaced = '@system/container.html.twig';
+    $class_namespaced = $environment->getTemplateClass($name_namespaced);
+    $key_namespaced = $environment->getCache()->generateKey($name_namespaced, $class_namespaced);
+
+    // Test using a direct filesystem template path.
+    $name_direct = 'core/modules/system/templates/container.html.twig';
+    $class_direct = $environment->getTemplateClass($name_direct);
+    $key_direct = $environment->getCache()->generateKey($name_direct, $class_direct);
+
+    // All three should be equal for both cases.
+    $this->assertEqual($class_include, $class_namespaced);
+    $this->assertEqual($class_namespaced, $class_direct);
+    $this->assertEqual($key_include, $key_namespaced);
+    $this->assertEqual($key_namespaced, $key_direct);
+  }
+
   /**
    * Ensures that cacheFilename() varies by extensions + deployment identifier.
    */