DeprecatedServicePass.php

<?php

namespace Drupal\Core\DependencyInjection\Compiler;

use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;

/**
 * Sets the _deprecated_service_list parameter.
 *
 * @see \Drupal\Component\DependencyInjection\Container::get()
 */
class DeprecatedServicePass implements CompilerPassInterface {
    
    /**
     * {@inheritdoc}
     */
    public function process(ContainerBuilder $container) {
        $deprecated_services = [];
        foreach ($container->getDefinitions() as $service_id => $definition) {
            if ($definition->isDeprecated()) {
                $deprecated_services[$service_id] = $definition->getDeprecation($service_id)['message'];
            }
        }
        foreach ($container->getAliases() as $service_id => $definition) {
            if ($definition->isDeprecated()) {
                $deprecated_services[$service_id] = $definition->getDeprecation($service_id)['message'];
            }
        }
        $container->setParameter('_deprecated_service_list', $deprecated_services);
    }

}