WordPress at a glance
filter is not described

redirect_canonical filter-hook . WP 2.3.0

Filters the canonical redirect URL.

Returning false to this filter will cancel the redirect.

Usage

add_filter( 'redirect_canonical', 'filter_function_name_4777', 10, 2 );
function filter_function_name_4777( $redirect_url, $requested_url ){
	// filter...

	return $redirect_url;
}
$redirect_url(string)
The redirect URL.
$requested_url(string)
The requested URL.

Where the hook is called

redirect_canonical()
wp-includes/canonical.php 523
$redirect_url = apply_filters( 'redirect_canonical', $redirect_url, $requested_url );

Where the hook is used (in WP core)

Does not used.