Complex PHP-DI Configuration based on build time variable

For my PHP-DI definitions I need to make complex calculations beforhand, which are based on other configurations not coming from PHP-DI (those configurations are stored at build time in a variable). As it is harder to explain, than to show, let me give a simplified example which will show, what I would like to do, but will actually not work.

First let’s build the container. The code here is nothing special and shoud work:

<?php

use DIContainer;
use DIContainerBuilder;

class MyContainerBuilder
{
    // @param number is the build time (configuration) variable
    // I would like to use later
    public function build(int $number): Container
    {
        $builder = new DIContainerBuilder();
        $builder->addDefinitions(['number' => $number]);
        // In config.php I now want to do some complex calculations
        $builder->addDefinitions(__DIR__ . '/config.php');
        // here the container may be compiled, such that in production, the complex 
        // calculations from `config.php` will only be done once (to my understanding)
        return $builder->build();
    }
}

Now comes the problematic part. The calculation in config.php

<?php

$number = $container->get('number');
// complex calculation:
$number += 1;

return [
    'improvedNumber' => $number,
];

This is of course not possible, since the php-di container seems not to be available in the configuration file. Is it still possible to make the value of $number somehow available in the config.php?

Sidenote: What I really try to archive is to determine a bunch of services, which shall be injected using php-di. Those services are located in several directories and those directories I must know, when searching for them in the config.php-file.