I see 1 way to improve it: the visibility of the alias being added here should be set based on the visibility of the decorated service, so that decorating a private service does not turn it into a public one:

```php
if ($container->hasAlias($decorated)) {
    $alias = $container->getAlias($decorated);
    $public = $alias->isPublic();
    $container->setAlias($renamedId, new Alias((string) $alias, false));
} else {
    $definition = $container->getDefinition($decorated); 
    $public = $definition->isPublic();
    $definition->setPublic(false); 
    $container->setDefinition($renamedId, $definition);
}

$container->setAlias($decorated, new Alias($id, $public)); 
```