Macro flutter_rust_bridge::opaque_dyn

macro_rules! opaque_dyn {
    ($ex:expr) => { ... };
}

Macro helper to instantiate an RustOpaque<dyn Trait>, as Rust does not support custom DSTs on stable.

Example:

use std::fmt::Debug;
use flutter_rust_bridge::*;

pub trait MyDebug: DartSafe + Debug {}

impl<T: DartSafe + Debug> MyDebug for T {}

let opaque: RustOpaque<Box<dyn MyDebug>> = opaque_dyn!("foobar");