rwf2/Rocket

Phase out async_trait macro

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#2,684 opened on Dec 30, 2023

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 (5 comments) (6 reactions) (0 assignees)Rust (25,738 stars) (1,645 forks)batch import
acceptedhelp wantedrequest

Description

What's missing?

Rocket currently re-exports the async_trait crate for use with its Fairing (and possibly others). As of rust 1.75.0 this is no longer needed, therefore it would be nice to get rid of this dependency and use actual async functions for these traits.

This generally improves compile times, dependency count and IDE responsiveness.

Ideal Solution

For v0.6, remove async_trait (or put its usage behind a feature) and use async functions directly. This would raise the MSRV to 1.75.0.

Why can't this be implemented outside of Rocket?

This is an integral part of Rocket.

Are there workarounds usable today?

No. You bypass the need for the macro attribute by returning a Box<dyn Future<Output = T> + Send + 'a>, but this is unwieldy.

Alternative Solutions

No response

Additional Context

No response

System Checks

  • I do not believe that this feature can or should be implemented outside of Rocket.
  • I was unable to find a previous request for this feature.

Contributor guide

Tech stack
rust
Domain
backend
Issue type
refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Rust knowledgeAsync programming in RustFamiliarity with Rocket's Fairing trait
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Look for all usages of `async trait` in the Rocket codebase, particularly in the `Fairing` trait and any other traits that currently use the `#[async trait]` attribute. Check the `Cargo.toml` for the `async trait` dependency and its feature flags. The goal is to replace each `#[async trait]` attribute with `async fn` in trait definitions and implementations, and remove the dependency. Consider raising the MSRV to 1.75.0 as mentioned.
Phase out async_trait macro · rwf2/Rocket#2684 | Good First Issue