in src/uriparameters/spec/EnumParameterCodegenSpec.hack [15:25]
private static function cast<T>(
RequestParameter $param,
): EnumRequestParameter<T> {
invariant(
$param is EnumRequestParameter<_>,
'Expected %s to be an enum parameter, got %s',
$param->getName(),
\get_class($param),
);
return /* HH_FIXME[4110] unsafe generic */ $param;
}