async-trait

Look at the extremely popular async_trait macro crate: https://crates.io/crates/async-trait . What it does under the hood is to box everything. See https://github.com/dtolnay/async-trait#explanation You would think that you should be able to desugar async traits to something that does not need to box. But this is not possible with stable rust. There is an effort to make this possible. See for example this discussion here: https://blog.rust-lang.org/inside-rust/2022/11/17/async-fn-i... Initially it was thought that Send bounds would not be needed, but community feedback strongly suggests that Send is indeed needed. https://blog.rust-lang.org/inside-rust/2023/05/03/stabilizin... All this is a real problem, and not just a "you are holding it wrong" problem. Edit: here is the - still open - issue about higher-ranked lifetime errors: https://g

This macro goes a very long way toward solving the problem: https://github.com/dtolnay/async-trait