diff --git a/core/lib/Drupal/Core/Template/TwigExtension.php b/core/lib/Drupal/Core/Template/TwigExtension.php
index 05c7390..cf3500e 100644
--- a/core/lib/Drupal/Core/Template/TwigExtension.php
+++ b/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -82,6 +82,10 @@ public function getFilters() {
// Array filters.
new \Twig_SimpleFilter('without', 'twig_without'),
+
+ // CSS class and ID filters.
+ new \Twig_SimpleFilter('clean_class', 'drupal_html_class'),
+ new \Twig_SimpleFilter('clean_id', 'drupal_clean_id_identifier'),
);
}
diff --git a/core/modules/system/src/Tests/Theme/TwigFilterTest.php b/core/modules/system/src/Tests/Theme/TwigFilterTest.php
index c22be7f..5a285c7 100644
--- a/core/modules/system/src/Tests/Theme/TwigFilterTest.php
+++ b/core/modules/system/src/Tests/Theme/TwigFilterTest.php
@@ -111,6 +111,10 @@ public function testTwigWithoutFilter() {
'expected' => '
All attributes again.
',
'message' => 'All attributes printed again.',
),
+ array(
+ 'expected' => 'ID and class. Having the same ID twice is not valid markup but we want to make sure the filter doesn\'t use drupal_html_id().
',
+ 'message' => 'Class and ID filtered.',
+ ),
);
foreach ($elements as $element) {
diff --git a/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.filter.html.twig b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.filter.html.twig
index 28e5c15..cc7bc56 100644
--- a/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.filter.html.twig
+++ b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.filter.html.twig
@@ -20,3 +20,4 @@
Without string attribute.
Without either nor class attributes.
All attributes again.
+ID and class. Having the same ID twice is not valid markup but we want to make sure the filter doesn't use drupal_html_id().