Undefined static method Drupal\Core\Database\Connection::serialize()

Problem/Motivation

Discovered by PHPStan in #3178534: Start running PHPStan on Drupal core (level 0)

\Drupal\Core\Database\Driver\mysql\Connection::serialize() reads as follows:

  /**
   * {@inheritdoc}
   */
  public function serialize() {
    // Cleanup the connection, much like __destruct() does it as well.
    if ($this->needsCleanup) {
      $this->nextIdDelete();
    }
    $this->needsCleanup = FALSE;

    return parent::serialize();
  }

However the parent class has no serialize() method, and it does not implement the Serializable interface.

Steps to reproduce

Try to call serialize() directly:

>>> \Drupal::database()->serialize();
PHP Error:  Call to undefined method Drupal/Core/Database/Connection::serialize() in /var/www/html/drupal/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php on line 213

Proposed resolution

Remove this code.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet