WordPress at a glance
function is not described

filter_SSL() WP 2.8.5

Formats a URL to use https.

Useful as a filter.

No Hooks.

Return

String. URL with https as the scheme

Usage

filter_SSL( $url );
$url(string) (required)
URL

Code of filter SSL: wp-includes/ms-functions.php WP 5.2.2

<?php
function filter_SSL( $url ) {
	if ( ! is_string( $url ) ) {
		return get_bloginfo( 'url' ); // Return home blog url with proper scheme
	}

	if ( force_ssl_content() && is_ssl() ) {
		$url = set_url_scheme( $url, 'https' );
	}

	return $url;
}