ap( 'strtolower', (array) apply_filters( 'illegal_user_logins', array() ) );
		if ( in_array( strtolower( $sanitized_user_login ), $illegal_user_logins ) ) {
			$errors->add( 'invalid_username', __( '<strong>ERROR</strong>: Sorry, that username is not allowed.' ) );
		}
	}

	// Check the email address
	if ( $user_email == '' ) {
		$errors->add( 'empty_email', __( '<strong>ERROR</strong>: Please type your email address.' ) );
	} elseif ( ! is_email( $user_email ) ) {
		$errors->add( 'invalid_email', __( '<strong>ERROR</strong>: The email address isn&#8217;t correct.' ) );
		$user_email = '';
	} elseif ( email_exists( $user_email ) ) {
		$errors->add( 'email_exists', __( '<strong>ERROR</strong>: This email is already registered, please choose another one.' ) );
	}

	/**
	 * Fires when submitting registration form data, before the user is created.
	 *
	 * @since 2.1.0
	 *
	 * @param string   $sanitized_user_login The submitted username after being sanitized.
	 * @param string   $user_email           The submitted email.
	 * @param WP_Error $errors               Contains any errors with submitted username and email,
	 *                                       e.g., an empty field, an invalid username or email,
	 *                                       or an existing username or email.
	 */
	do_action( 'register_post', $sanitized_user_login, $user_email, $errors );

	/**
	 * Filters the errors encountered when a new user is being registered.
	 *
	 * The filtered WP_Error object may, for example, contain errors for an invalid
	 * or existing username or email address. A WP_Error object should always returned,
	 * but may or may not contain errors.
	 *
	 * If any errors are present in $errors, this will abort the user's registration.
	 *
	 * @since 2.1.0
	 *
	 * @param WP_Error $errors               A WP_Error object containing any errors encountered
	 *                                       during registration.
	 * @param string   $sanitized_user_login User's username after it has been sanitized.
	 * @param string   $user_email           User's email.
	 */
	$errors = apply_filters( 'registration_errors', $errors, $sanitized_user_login, $user_email );

	if ( $errors->get_error_code() )
		return $errors;

	$user_pass = wp_generate_password( 12, false );
	$user_id = wp_create_user( $sanitized_user_login, $user_pass, $user_email );
	if ( ! $user_id || is_wp_error( $user_id ) ) {
		$errors->add( 'registerfail', sprintf( __( '<strong>ERROR</strong>: Couldn&#8217;t register you&hellip; please contact the <a href="mailto:%s">webmaster</a> !' ), get_option( 'admin_email' ) ) );
		return $errors;
	}

	update_user_option( $user_id, 'default_password_nag', true, true ); //Set up the Password change nag.

	/**
	 * Fires after a new user registration has been recorded.
	 *
	 * @since 4.4.0
	 *
	 * @param int $user_id ID of the newly registered user.
	 */
	do_action( 'register_new_user', $user_id );

	return $user_id;
}

/**
 * Initiates email notifications related to the creation of new users.
 *
 * Notifications are sent both to the site admin and to the newly created user.
 *
 * @since 4.4.0
 * @since 4.6.0 Converted the `$notify` parameter to accept 'user' for sending
 *              notifications only to the user created.
 *
 * @param int    $user_id ID of the newly created user.
 * @param string $notify  Optional. Type of notification that should happen. Accepts 'admin'
 *                        or an empty string (admin only), 'user', or 'both' (admin and user).
 *                        Default 'both'.
 */
function wp_send_new_user_notifications( $user_id, $notify = 'both' ) {
	wp_new_user_notification( $user_id, null, $notify );
}

/**
 * Retrieve the current session token from the logged_in cookie.
 *
 * @since 4.0.0
 *
 * @return string Token.
 */
function wp_get_session_token() {
	$cookie = wp_parse_auth_cookie( '', 'logged_in' );
	return ! empty( $cookie['token'] ) ? $cookie['token'] : '';
}

/**
 * Retrieve a list of sessions for the current user.
 *
 * @since 4.0.0
 * @return array Array of sessions.
 */
function wp_get_all_sessions() {
	$manager = WP_Session_Tokens::get_instance( get_current_user_id() );
	return $manager->get_all();
}

/**
 * Remove the current session token from the database.
 *
 * @since 4.0.0
 */
function wp_destroy_current_session() {
	$token = wp_get_session_token();
	if ( $token ) {
		$manager = WP_Session_Tokens::get_instance( get_current_user_id() );
		$manager->destroy( $token );
	}
}

/**
 * Remove all but the current session token for the current user for the database.
 *
 * @since 4.0.0
 */
function wp_destroy_other_sessions() {
	$token = wp_get_session_token();
	if ( $token ) {
		$manager = WP_Session_Tokens::get_instance( get_current_user_id() );
		$manager->destroy_others( $token );
	}
}

/**
 * Remove all session tokens for the current user from the database.
 *
 * @since 4.0.0
 */
function wp_destroy_all_sessions() {
	$manager = WP_Session_Tokens::get_instance( get_current_user_id() );
	$manager->destroy_all();
}

/**
 * Get the user IDs of all users with no role on this site.
 *
 * This function returns an empty array when used on Multisite.
 *
 * @since 4.4.0
 *
 * @return array Array of user IDs.
 */
function wp_get_users_with_no_role() {
	global $wpdb;

	if ( is_multisite() ) {
		return array();
	}

	$prefix = $wpdb->get_blog_prefix();
	$regex  = implode( '|', array_keys( wp_roles()->get_names() ) );
	$regex  = preg_replace( '/[^a-zA-Z_\|-]/', '', $regex );
	$users  = $wpdb->get_col( $wpdb->prepare( "
		SELECT user_id
		FROM $wpdb->usermeta
		WHERE meta_key = '{$prefix}capabilities'
		AND meta_value NOT REGEXP %s
	", $regex ) );

	return $users;
}

/**
 * Retrieves the current user object.
 *
 * Will set the current user, if the current user is not set. The current user
 * will be set to the logged-in person. If no user is logged-in, then it will
 * set the current user to 0, which is invalid and won't have any permissions.
 *
 * This function is used by the pluggable functions wp_get_current_user() and
 * get_currentuserinfo(), the latter of which is deprecated but used for backward
 * compatibility.
 *
 * @since 4.5.0
 * @access private
 *
 * @see wp_get_current_user()
 * @global WP_User $current_user Checks if the current user is set.
 *
 * @return WP_User Current WP_User instance.
 */
function _wp_get_current_user() {
	global $current_user;

	if ( ! empty( $current_user ) ) {
		if ( $current_user instanceof WP_User ) {
			return $current_user;
		}

		// Upgrade stdClass to WP_User
		if ( is_object( $current_user ) && isset( $current_user->ID ) ) {
			$cur_id = $current_user->ID;
			$current_user = null;
			wp_set_current_user( $cur_id );
			return $current_user;
		}

		// $current_user has a junk value. Force to WP_User with ID 0.
		$current_user = null;
		wp_set_current_user( 0 );
		return $current_user;
	}

	if ( defined('XMLRPC_REQUEST') && XMLRPC_REQUEST ) {
		wp_set_current_user( 0 );
		return $current_user;
	}

	/**
	 * Filters the current user.
	 *
	 * The default filters use this to determine the current user from the
	 * request's cookies, if available.
	 *
	 * Returning a value of false will effectively short-circuit setting
	 * the current user.
	 *
	 * @since 3.9.0
	 *
	 * @param int|bool $user_id User ID if one has been determined, false otherwise.
	 */
	$user_id = apply_filters( 'determine_current_user', false );
	if ( ! $user_id ) {
		wp_set_current_user( 0 );
		return $current_user;
	}

	wp_set_current_user( $user_id );

	return $current_user;
}