wp-includes/pluggable.php:83Retrieves user info by user ID.
$user_idintWP_User|false function get_userdata( $user_id ) { return get_user_by( 'id', $user_id ); }Introduced in 0.71. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/pluggable.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.