Tracing's log feature should not cause code that would otherwise compile to break

[Noah-Kennedy]

Currently, enabling the log feature in tracing can break code that would otherwise compile, which is a problem, as features are generally supposed to be additive. This leads to situations such as projects breaking when trying to use console, as Tonic enables the default features in tower, which enables this feature in tracing.

There has already been some discussion about this in the discord server.

Thread 1: https://discord.com/channels/500028886025895936/838895414455435335/905519088934211584
Thread 2: https://discord.com/channels/500028886025895936/838895414455435335/921838120788459561

[Noah-Kennedy]

Bumping this, it's been long enough and it's a very easy problem to hit nowadays, especially with console-subscriber.

[hawkw]

I thought this issue was fixed in #1823? Are you still seeing errors with an up-to-date tracing dependency?

[Noah-Kennedy]

Yes, I am sadly seeing this in v0.1.33

[hawkw]

Can you share the error you're seeing? The issue fixed by #1823 is the only one I'm aware of, so I'd like to see if this is the same problem or a different one.

[Noah-Kennedy]

@hawkw I'll get an mcre up shortly

[Noah-Kennedy]

@hawkw I have an MCRE here: https://github.com/Noah-Kennedy/another-tracing-mcre

In a nutshell:

#[tokio::main(flavor = "current_thread")]
async fn main() {
    tracing_subscriber::fmt().init();
    tokio::spawn(do_request()).await.unwrap();
}

async fn do_request() {
    let response = reqwest::get("https://google.com").await.unwrap();
    tracing::info!("{}", response.text().await.unwrap());
}

This fails with tracing/log enabled because the future returned by do_request is no longer Send, but works without that feature. I suspect that this would work with any await held in that position. I shall attempt to minify further.

[Noah-Kennedy]

Got it working without reqwest:

#[tokio::main(flavor = "current_thread")]
async fn main() {
    tokio::spawn(do_request()).await.unwrap();
}

async fn do_request() {
    tracing::info!("{}", std::future::ready("test").await);
}

The tokio::spawn is basically just there to assert that the resulting future is Send.