<?php

use Symfony\Component\Validator\ValidatorBuilder;
use Symfony\Component\Validator\Constraints as C;
use Symfony\Component\Validator\ConstraintViolationList;
use Doctrine\Common\Annotations\AnnotationRegistry;

$projectRootPath = '/path/to/project';

/**
 * @C\Expression(
 *     expression="this.start < this.end",
 *     message="Why is you start value bigger than the end value?"
 * )
 */
$object = new class() {
    public $start = 10;
    public $end = 5;
};

// Validator uses Doctrine Annotation library
AnnotationRegistry::registerAutoloadNamespace(
    'Symfony\Component\Validator\Constraints',
    $projectRootPath . '/vendor/symfony/symfony/src'
);

$validator = (new ValidatorBuilder())
    ->enableAnnotationMapping()
    ->getValidator();

$violationList = $validator->validate($object);

dump($violationList[0]->getMessage());

^ "Why is you start value bigger than the end value?"

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PHP 8.3, Laminas MVC 3.2, Symfony 5.2, Laravel 8.28, PHPUnit 9.5, Doctrine ORM 2.8