Is the async_trait still necessary for dync Trait with async methods? (programming.dev)

submitted 4 days ago by onlinepersona@programming.dev to c/rust@programming.dev

7 comments fedilink hide all child comments

I just ran into the wonderful error message

the trait is not dyn compatible because method publish_video is async

and boy, what a rabbit hole. I found out about async_trait which resolves this by turning async methods into fn method() -> Pin<Box<dyn Future + Send + 'async_trait>>, but I thought that's what the async fn was syntax sugar for??? Then I ran into this member-only medium post claiming

Rust Async Traits: What Finally Works Now

Async functions in traits shipped. Here’s what that means for your service interfaces.

But I clicked through every rust release since 1.75.0 where impl AsyncTrait was shipped and couldn't find a mention of async. Now I'm just confused (and still using async_trait). Hence the question above...

you are viewing a single comment's thread
view the rest of the comments

[-] BB_C@programming.dev 4 points 4 days ago

dyn compatibility of the trait itself is another matter. In this case, an async method makes a trait not dyn-compatible because of the implicit -> impl Future opaque return type, as documented here.

But OP didn't mention whether dyn is actually needed or not. For me, dyn is almost always a crutch (exceptions exist).

this post was submitted on 22 Jan 2026

21 points (100.0% liked)

Rust

7697 readers

4 users here now

Welcome to the Rust community! This is a place to discuss about the Rust programming language.

Wormhole

!performance@programming.dev

Credits

The icon is a modified version of the official rust logo (changing the colors to a gradient and black background)

founded 2 years ago

MODERATORS

snowe@programming.dev

Ategon@programming.dev

EdTheLegendary@programming.dev

kahnclusions@programming.dev

torcherist@programming.dev