Opaque inside translatable

tip

There is no need to memorize anything here (or anything in doc) - the code generator will provide warnings when detecting non-best-practices.

Suppose you want to have a translatable struct, and it has an (auto) opaque field:

pub struct A { pub b: B }

// Suppose it is opaque
pub struct B { ... }

If you want to use the same object of type A multiple times, then it is suggested (and flutter_rust_bridge will automatically hint you about that) to add an RustAutoOpaque<...> wrapper on it:

-    pub b: B,
+    pub b: RustAutoOpaque<B>,

(Optional) explanations: This is because, shortly speaking, the original version needs to have an owned B, and thus the B object cannot be used later. On the other hand, the updated version, which uses RustAutoOpaque thus Arc, will only require shared ownership.

(Optional) In the future, we may utilize this feature, then the scenario above can be automatically handled without any change to RustAutoOpaque.