install.php should pass the class loader down into install_begin_request()

Problem/Motivation

Drupal cannot be installed by an external script if that external script is bootstrapped via Composer's autoloader and that autoloader contains Drupal as well.

For a more concrete use-case, given a Composer project that pulls in both Drupal and Drush, drush site-install will not work. Drush will bootstrap itself with Composer's autoloader (the one in /path/to/project/vendor/autoload.php) and then the installer will include Drupal's autoloader (the one in /path/to/drupal/core/vendor/autoload.php). Both will try to require core/lib/Drupal.php and, thus, the second one fails.

Proposed resolution

The basic idea is to remove loading an autoloader from somewhere else than the frontcontrollers (index.php, install.php, ...).

Pass down the classloader into install_drupal() and install_being_request(). That way Drush and other scripts can pass in the right classloader from the start.

Note that for drush site-install to work, the latest Drush master is required and the following hunk must be applied to drush_core_site_install_version() in commands/core/drupal/site_install.inc:

$msg .= ' Consider using the --notify global option.';
}
drush_log(dt($msg), 'ok');
- drush_op('install_drupal', $settings);
+ $class_loader = drush_drupal_load_autoloader(DRUPAL_ROOT);
+ drush_op('install_drupal', $class_loader, $settings);
drush_log(dt('Installation complete. User name: @name User password: @pass', array('@name' => $account_name, '@pass' => $account_pass)), 'ok');
}

Remaining tasks

User interface changes

Note.

API changes

install_drupal() and install_begin_request() have a new (non-optional) $class_loader argument.

Beta phase evaluation