Signal with generic argument not working since 5.0.0

[jbbjarnason]

I updated from 4.4.0 where the following code worked:

    #[zbus(signal)]
    async fn value(signal_ctxt: &zbus::SignalContext<'_>, val: &T) -> zbus::Result<()>;

to 5.2.0(same as 5.0.0) where I have changed this code to

    #[zbus(signal)]
    async fn value(
        signal_ctxt: &zbus::object_server::SignalEmitter<'_>,
        val: &T,
    ) -> Result<(), zbus::Error>;

but I get this weird compile error:

error[E0412]: cannot find type `T` in this scope
   --> src/ipc/dbus.rs:135:15
    |
135 |         val: &T,
    |               ^ not found in this scope

please note that T is part of the impl section that has not changed.

full code:

#[interface(name = "is.centroid.Signal")]
impl<T> SignalInterface<T>
where
    T: Clone
        + detail::SupportedTypes
        + zbus::zvariant::Type
        + Sync
        + Send
        + 'static
        + JsonSchema
        + for<'a> zbus::export::serde::de::Deserialize<'a>
        + zbus::export::serde::ser::Serialize,
{
    #[zbus(property, name = "Value")]
    fn value_prop(&self) -> Result<zbus::zvariant::Value<'static>, zbus::fdo::Error> {
        let ref_val = self.value_receiver.borrow();

        match *ref_val {
            Some(ref value) => Ok(value.to_value()), // this copies but is unfrequent
            None => Err(zbus::fdo::Error::Failed("No value set".into())),
        }
    }
    #[zbus(property(emits_changed_signal = "const"))]
    fn schema(&self) -> Result<String, zbus::fdo::Error> {
        serde_json::to_string_pretty(&schemars::schema_for!(T)).map_err(|e| {
            let err_msg = format!("Error serializing to JSON schema: {}", e);
            log!(target: &self.log_key, Level::Error, "{}", err_msg);
            zbus::fdo::Error::Failed(err_msg)
        })
    }
    fn last_value(&self) -> Result<T, zbus::fdo::Error> {
        let ref_val = self.value_receiver.borrow();

        match *ref_val {
            Some(ref value) => Ok(value.clone()),
            None => Err(zbus::fdo::Error::Failed("No value set".into())),
        }
    }
    #[zbus(signal)]
    async fn value(
        signal_ctxt: &zbus::object_server::SignalEmitter<'_>,
        val: &T,
    ) -> Result<(), zbus::Error>;
}