Posts: Fix hierarchical parent selection for pages with non-published ancestors

src/wp-admin/includes/meta-boxes.php

@@ -1010,6 +1010,7 @@ function page_attributes_meta_box( $post ) {
 			'show_option_none' => __( '(no parent)' ),
 			'sort_column'      => 'menu_order, post_title',
 			'echo'             => 0,
+			'post_status'      => array( 'publish', 'draft', 'pending', 'private' ),
 		);
 
 		/**

src/wp-includes/post.php

@@ -6268,6 +6268,23 @@ function get_page_children( $page_id, $pages ) {
 		}
 	}
 
+	if ( 0 === $page_id ) {
+		$parent_ids = array_keys( $children );
+		$page_ids   = wp_list_pluck( $pages, 'ID' );
+
+		foreach ( $parent_ids as $parent_id ) {
+			if ( 0 !== $parent_id && ! in_array( $parent_id, $page_ids, true ) ) {
+				foreach ( $children[ $parent_id ] as $orphan ) {
+					$page_list[] = $orphan;
+					if ( isset( $children[ $orphan->ID ] ) ) {
+						$orphan_pages = get_page_children( $orphan->ID, $pages );
+						$page_list    = array_merge( $page_list, $orphan_pages );
+					}
+				}
+			}
+		}
+	}
+
 	return $page_list;
 }
 

tests/phpunit/tests/post/wpDropdownPages.php

@@ -219,4 +219,65 @@ public function test_wp_dropdown_pages_should_obey_class_parameter() {
 
 		$this->assertMatchesRegularExpression( '/<select[^>]+class=\'bar\'/', $found );
 	}
+
+	/**
+	 * Test that published child pages remain selectable when parent is trashed.
+	 *
+	 * @ticket 11235
+	 */
+	public function test_child_page_available_when_parent_trashed() {
+		$parent_id = self::factory()->post->create(
+			array(
+				'post_type'   => 'page',
+				'post_status' => 'publish',
+			)
+		);
+
+		$child_id = self::factory()->post->create(
+			array(
+				'post_type'   => 'page',
+				'post_parent' => $parent_id,
+				'post_status' => 'publish',
+			)
+		);
+
+		wp_trash_post( $parent_id );
+
+		$output = wp_dropdown_pages( array( 'echo' => 0 ) );
+
+		$this->assertStringContainsString( 'value="' . $child_id . '"', $output, 'Published child page should remain available even when parent is trashed.' );
+		$this->assertStringNotContainsString( 'value="' . $parent_id . '"', $output, 'Trashed parent should not appear in dropdown.' );
+	}
+
+	/**
+	 * Test that published child pages remain selectable when parent is draft or pending.
+	 *
+	 * @ticket 11235
+	 */
+	public function test_child_page_available_when_parent_not_published() {
+		$parent_id = self::factory()->post->create(
+			array(
+				'post_type'   => 'page',
+				'post_status' => 'publish',
+			)
+		);
+
+		$child_id = self::factory()->post->create(
+			array(
+				'post_type'   => 'page',
+				'post_parent' => $parent_id,
+				'post_status' => 'publish',
+			)
+		);
+
+		wp_update_post(
+			array(
+				'ID'          => $parent_id,
+				'post_status' => 'draft',
+			)
+		);
+
+		$output = wp_dropdown_pages( array( 'echo' => 0 ) );
+		$this->assertStringContainsString( 'value="' . $child_id . '"', $output, 'Published child should be available when parent is draft.' );
+	}
 }