SubscriberExt::with cant be used on a Box<dyn Subscriber>.

[Devlyn-Nelson]

Is there a reason tracing_subscriber::sealed::Sealed is private? because it removes the ability to use SubscriberExt on something like a Box<dyn Subscriber> because i can't require Sealed.

[hawkw]

SubscriberExt is implemented for all S where S implements Subscriber. The trait is sealed to prevent it from being implemented for types that don't implement Subscriber, as this wouldn't be useful or make sense.

If you can't call with on a Box<dyn Subscriber>, that's because dyn Subscriber doesn't implement Subscriber. We should fix this by adding an impl Subscriber for dyn Subscriber in the tracing-core crate.

[Devlyn-Nelson]

are we talking about the same thing? https://docs.rs/tracing-subscriber/latest/tracing_subscriber/layer/trait.SubscriberExt.html

[hawkw]

Yes, note that there is a blanket implementation of SubscriberExt for all S where S: Subscriber: https://docs.rs/tracing-subscriber/latest/tracing_subscriber/layer/trait.SubscriberExt.html#impl-SubscriberExt-for-S

[Devlyn-Nelson]

I see. I don't get it why its Subscriber + Sealed if it gets blanketed to any Subscriber anyway, but i will trust that it makes sense in the larger picture. I will comeback to this when i have more time to mess around with nonessential improvements. Thank you and all the other tokio devs.

[hawkw]

I don't think that sealing the trait to prevent downstream implementations was actually necessary, and we could definitely remove it. But, we would still need to solve the problem of a missing subscriber implementation for Box<dyn Subscriber>.