act_zero
macro_rules! upcast { ($x:expr) => { ... }; }
Converts an Addr<T> or WeakAddr<T> to an Addr<dyn Trait> or WeakAddr<dyn Trait>.
Addr<T>
WeakAddr<T>
Addr<dyn Trait>
WeakAddr<dyn Trait>
let trait_addr: Addr<dyn Trait> = upcast!(addr);