Attribute Macro async_trait 

#[async_trait]

Retrofits support for async fn in trait impls and declarations.

Any trait declaration or trait impl decorated with #[async_trait] is retrofitted with support for async fns:

#[async_trait]
trait MyAsyncTrait {
    async fn do_async_work();
}

#[async_trait]
impl MyAsyncTrait for () {
    async fn do_async_work() { /* .. */ }
}

All impls for a trait declared with #[async_trait] must themselves be decorated with #[async_trait]. Many of Rocket’s traits, such as FromRequest and Fairing are async. As such, implementations of said traits must be decorated with #[async_trait]. See the individual trait docs for trait-specific details.

For more details on #[async_trait], see async_trait.