WordPress at a glance
filter is not described

pre_post_link filter-hook . WP 3.0.0

Filters the permalink structure for a post before token replacement occurs.

Only applies to posts with post_type of 'post'.

Usage

add_filter( 'pre_post_link', 'filter_function_name_7061', 10, 3 );
function filter_function_name_7061( $permalink, $post, $leavename ){
	// filter...

	return $permalink;
}
$permalink(string)
The site's permalink structure.
$post(WP_Post)
The post in question.
$leavename(true/false)
Whether to keep the post name.

Where the hook is called

get_permalink()
pre_post_link
wp-includes/link-template.php 163
$permalink = apply_filters( 'pre_post_link', $permalink, $post, $leavename );

Where the hook is used (in WP core)

Does not used.