wp-admin/includes/upgrade.php:1553Remove old categories, link2cat, and post2cat database tables.
function upgrade_230_old_tables() { global $wpdb; $wpdb->query( 'DROP TABLE IF EXISTS ' . $wpdb->prefix . 'categories' ); $wpdb->query( 'DROP TABLE IF EXISTS ' . $wpdb->prefix . 'link2cat' ); $wpdb->query( 'DROP TABLE IF EXISTS ' . $wpdb->prefix . 'post2cat' );}Introduced in 2.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/upgrade.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.