permalink_anchor( string $mode = 'id' )

Source

File: wp-includes/link-template.php

function permalink_anchor( $mode = 'id' ) {
	$post = get_post();
	switch ( strtolower( $mode ) ) {
		case 'title':
			$title = sanitize_title( $post->post_title ) . '-' . $post->ID;
			echo '<a id="' . $title . '"></a>';
			break;
		case 'id':
		default:
			echo '<a id="post-' . $post->ID . '"></a>';
			break;
	}
}