Tag "trans" is already registered error when symfony/twig-bridge is installed

[plopesc]

Description

When symfony/twig-bridge is installed alongside twig-cs-fixer-drupal, running twig-cs-fixer lint fails with:

Error: Tag "trans" is already registered.

Root Cause

DrupalConfig::getConfig() explicitly adds Drupal's TwigTransTokenParser (tag: trans) at line 30:

$config->addTokenParser(new TwigTransTokenParser());

However, StubbedEnvironment::__construct() in vincentlanglet/twig-cs-fixer calls handleOptionalDependencies() before processing custom token parsers. That method registers Symfony's TransTokenParser (also tag: trans) when symfony/twig-bridge is present:

if (class_exists(TransTokenParser::class)) {
    $this->addTokenParser(new TransTokenParser());
}

Twig's StagingExtension::addTokenParser() throws a LogicException when a tag is registered twice — there's no override mechanism.

So the registration order is:

1. StubbedEnvironment::handleOptionalDependencies() → Symfony's TransTokenParser (trans) ✅
2. Custom token parsers from config → Drupal's TwigTransTokenParser (trans) ❌ throws

How to Reproduce

Install a project where symfony/twig-bridge is pulled in by another dependency (e.g. simplesamlphp/simplesamlphp), then run:

vendor/bin/twig-cs-fixer lint

With .twig-cs-fixer.php:

<?php
return \TwigCsFixerDrupal\DrupalConfig::getConfig();

Suggested Fix

DrupalConfig::getConfig() should check whether the trans tag will already be handled by StubbedEnvironment before adding the Drupal token parser. For example:

// Only add Drupal's TwigTransTokenParser if the Symfony Bridge one won't
// be auto-registered by StubbedEnvironment::handleOptionalDependencies().
if (!class_exists(\Symfony\Bridge\Twig\TokenParser\TransTokenParser::class)) {
    $config->addTokenParser(new TwigTransTokenParser());
}

Workaround

Replicate DrupalConfig::getConfig() in .twig-cs-fixer.php without the TwigTransTokenParser line. For linting purposes, Symfony's TransTokenParser handles the {% trans %} syntax adequately.

Versions

• lullabot/twig-cs-fixer-drupal: 2.3.0
• vincentlanglet/twig-cs-fixer: 3.14.0
• twig/twig: 3.x
• symfony/twig-bridge: 6.4.x (required by simplesamlphp/simplesamlphp)