Added u string extension: https://twig.symfony.com/doc/3.x/filters/u.html

Author: thampe

Framework/View/TemplateEngine/Twig.php

@@ -20,6 +20,8 @@
 use Twig\TemplateWrapper;
 use Twig\TwigFilter;
 use Twig\TwigFunction;
+use Twig\Extra\String\StringExtension;
+
 
 class Twig extends Php
 {
@@ -106,6 +108,7 @@ private function initTwig()
 
         $this->twig->addFilter(new TwigFilter('trans', '__'));
         $this->twig->addExtension(new DebugExtension());
+        $twig->addExtension(new StringExtension());
         $this->eventManager->dispatch('twig_init', ['twig' => $this->twig]);
     }
 

composer.json

@@ -6,7 +6,8 @@
         "magento/framework": ">=100.0.0",
         "magento/module-backend": ">=100.0.0",
         "magento/module-config": ">=100.0.0",
-        "twig/twig": "^3.0"
+        "twig/twig": "^3.0",
+        "twig/string-extra":"^3.3"
     },
     "type": "magento2-module",
     "version": "2.0.1",