Issue #3502069 by just_like_good_vibes, christian.wiedemann, pdureau,...

Issue #3502069 by just_like_good_vibes, christian.wiedemann, pdureau, grimreaper: Duplicate blocks when nested ComponentLayout with Layout Builder

modules/ui_patterns_layouts/src/Plugin/Layout/ComponentLayout.php

@@ -132,12 +132,11 @@ class ComponentLayout extends LayoutDefault implements ContainerFactoryPluginInt
         continue;
       }
       $build['#slots'][$region_name] = $regions[$region_name];
-      // For layout builder we need to pass slots also
-      // direct to the build array. They are needed to generate contextual
-      // links and other surrounding markup.
-      // This makes field layout forms empty.
-      // Not sure how to handle this. Should we support field_layout?
-      $build[$region_name] = $regions[$region_name];
+      // Add a reference from slots to regions
+      // Additional markup and contextual links are added
+      // by layout consumers.
+      // @see Drupal\layout_builder\Element\LayoutBuilder::buildAddSectionLink
+      $build[$region_name] = &$build['#slots'][$region_name];
     }
     return $build;
   }

modules/ui_patterns_layouts/tests/src/Functional/LayoutBuilderRenderTest.php

@@ -105,6 +105,9 @@ class LayoutBuilderRenderTest extends UiPatternsFunctionalTestBase {
     $page->clickLink('Add block');
     $page->clickLink('Text (formatted)');
     $page->pressButton('Add block');
+
+    // Check if layout specific classes are added.
+    $assert_session->elementExists('css', 'div[data-layout-block-uuid]');
     $page->pressButton('Save layout');
     $this->drupalGet('node/' . $node->id());
     $assert_session->elementExists('css', '.ui-patterns-test-component');