Macro parse_conf_value_impl 

macro_rules! parse_conf_value_impl {
    ($map:expr, $ty:ty, $errors:expr, $file:expr, $field_span:expr, (), ()) => { ... };
    ($map:expr, $ty:ty, $errors:expr, $file:expr, $field_span:expr, ($profiles:expr), ()) => { ... };
    ($map:expr, $ty:ty, $errors:expr, $file:expr, $field_span:expr, (), ($disallowed:expr)) => { ... };
    (
        $map:expr,
        $ty:ty,
        $errors:expr,
        $file:expr,
        $field_span:expr,
        ($profiles:expr),
        ($disallowed:expr)
    ) => { ... };
}