async_trait incompatible with builder-pattern

[clotodex]

I cannot get async_trait and builder-pattern to play nice together.

My test (assume MyAsyncTrait exists):

#[derive(Builder)]
pub struct MyStruct {
    a: SomeStructA,
    b_provider: Box<dyn MyAsyncTrait>,
}

It complains that MyAsyncTrait cannot be made into an object. My guess is that either the double-code generation breaks something OR that builder-pattern would need to place the #[async_trait] in its generated code too.

This is currently blocking me from using the builder pattern.

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If this is too hard to implement, Rust aims to support a first version of stable async traits (not via library) from 1.74, which should land in July. Then this might be resolved. What do you think?