wp-includes/widgets.php:1282Retrieves the widget ID base value.
$idstringstringfunction _get_widget_id_base( $id ) { return preg_replace( '/-[0-9]+$/', '', $id );}Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/widgets.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.