wp-includes/class-wpdb.php:832Makes private properties un-settable for backward compatibility.
$namestring public function __unset( $name ) { unset( $this->$name ); }Introduced in 3.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wpdb.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.