Merge "Floss: Propagate error at Option<T> decoding"

#[proc_macro]

pub fn generate_dbus_arg(_item: TokenStream) -> TokenStream {

    let gen = quote! {

        use dbus::arg::{PropMap, RefArg};

        use dbus::arg::RefArg;

        use dbus::nonblock::SyncConnection;

        use dbus::strings::BusName;

        use dbus_projection::DisconnectWatcher;

                remote: Option<BusName<'static>>,

                disconnect_watcher: Option<Arc<Mutex<DisconnectWatcher>>>)

                -> Result<Option<T>, Box<dyn Error>> {

                let mut result: Option<T> = None;

                // It's Ok if the key doesn't exist. That just means we have an empty option (i.e.

                // None).

                let value = match T::from_dbus(ref_value, conn, remote, disconnect_watcher) {

                    Ok(v) => Some(v),

                    Err(_) => None,

                    Err(e) => return Err(e),

                };

                Ok(value)