EmailConstraint.php

<?php

namespace Drupal\Core\Validation\Plugin\Validation\Constraint;

use Symfony\Component\Validator\Constraints\Email;

/**
 * Count constraint.
 *
 * Overrides the symfony constraint to use the strict setting.
 *
 * @Constraint(
 *   id = "Email",
 *   label = @Translation("Email", context = "Validation")
 * )
 */
class EmailConstraint extends Email {
    
    /**
     * {@inheritdoc}
     */
    public function __construct($options = []) {
        // Since Symfony 4.1, the 'mode' property is used, for previous versions the
        // 'strict' property. If the 'strict' property is set,
        // \Symfony\Component\Validator\Constraints\EmailValidator will trigger
        // a deprecation error, so only assign a value for versions of Symfony
        // < 4.2. This compatibility layer can be removed once Drupal requires
        // Symfony 4.2 or higher in https://www.drupal.org/node/3009219.
        if (property_exists($this, 'mode')) {
            $default_options = [
                'mode' => 'strict',
            ];
        }
        else {
            $default_options = [
                'strict' => TRUE,
            ];
        }
        $options += $default_options;
        parent::__construct($options);
    }
    
    /**
     * {@inheritdoc}
     */
    public function validatedBy() {
        return '\\Symfony\\Component\\Validator\\Constraints\\EmailValidator';
    }

}