New assertion breaks QueryBuilder with dummy driver

[Bilge]

I use the Doctrine QueryBuilder with a foreign database library. Since the QueryBuilder does not work without a driver, I create a dummy driver so I can just use the QueryBuilder. This worked until a BC break in a minor revision that added an assertion that disagrees with the type hint on the backing field.

BC Break Report

Q	A
BC Break	yes
Version	2.10.3

Summary

When upgrading from 2.10.2. to 2.10.3 my code breaks due to this change: e48861e

dbal/lib/Doctrine/DBAL/Connection.php

Line 1459 in e48861e

assert($this->_conn !== null);

Previous behaviour

Previously $this->_conn was allowed to be null. The type hint for $_conn still reads as nullable, but for some reason this assertion was added that disagrees with this.

dbal/lib/Doctrine/DBAL/Connection.php

Lines 82 to 87 in e48861e

	/**
	* The wrapped driver connection.
	*
	* @var \Doctrine\DBAL\Driver\Connection|null
	*/
	protected $_conn;

Current behavior

Since the assertions forces $_conn to be non-null, it breaks cases where $_conn is null.

How to reproduce

<?php
declare(strict_types=1);

use Doctrine\DBAL\Driver\AbstractPostgreSQLDriver;

final class DummyPostgresDriver extends AbstractPostgreSQLDriver
{
    public function connect(array $params, $username = null, $password = null, array $driverOptions = []): void
    {
        // Intentionally empty.
    }

    public function getName(): string
    {
        return __CLASS__;
    }
}

$qb = (new Doctrine\DBAL\Connection([], new DummyPostgresDriver))->createQueryBuilder();
$qb->setMaxResults(50); // Only occurs when max results is defined.
$qb->getSql(); // This eventually calls Connection::getWrappedConnection(), triggering the assertion to fail.

[greg0ire]

Before the assertion was added, there was a contract for implementations though:

dbal/lib/Doctrine/DBAL/Connection.php

Line 1453 in e48861e

* @return DriverConnection

The contract is enforced now, any implementation should already be compliant. You can work this around by disabling assertions, or you could implement the contract by returning a dummy implementation of DriverConnection.

[Bilge]

The class itself is already a DriverConnection. I could inject it into itself but that seems silly.

[greg0ire]

Doesn't having a dummy driver feel silly already? Anyway, I don't think we are going to revert this to humor this use case, sorry. Feels a bit too much like xkcd 1172

[Bilge]

Doesn't having a QueryBuilder tied to an active connection feel silly? I'm trying to work around these artificial constraints.

[greg0ire]

It sure does. Good luck with your issue.

[greg0ire]

Closing as per #4094 (comment)

[github-actions]

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