wp-admin/includes/upgrade.php:1568Upgrade old slugs made in version 2.2.
function upgrade_old_slugs() { // Upgrade people who were using the Redirect Old Slugs plugin. global $wpdb; $wpdb->query( "UPDATE $wpdb->postmeta SET meta_key = '_wp_old_slug' WHERE meta_key = 'old_slug'" );}Introduced in 2.2.0. 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.