Example given for tracing_subscriber::fmt::format doesn't work

[malaire]

Bug Report

Version

cargo tree | grep tracing reports

tracing v0.1.22
tracing-attributes v0.1.11
tracing-core v0.1.17
tracing-futures v0.2.4
tracing-log v0.1.1
tracing-serde v0.1.2
tracing-subscriber v0.2.15

Platform

Linux box 4.19.0-12-amd64 #1 SMP Debian 4.19.152-1 (2020-10-18) x86_64 GNU/Linux

Description

When using the example code shows at tracing_subscriber::fmt::format I get no tracing output at all with RUST_LOG=trace cargo run:

let format = tracing_subscriber::fmt::format()
    .without_time()         // Don't include timestamps
    .with_target(false)     // Don't include event targets.
    .with_level(false)      // Don't include event levels.
    .compact();             // Use a more compact, abbreviated format.

// Use the configured formatter when building a new subscriber.
tracing_subscriber::fmt()
    .event_format(format)
    .init();

When I instead use tracing_subscriber::fmt::init() I do get tracing output, so that example is not working.

[malaire]

It looks like the problem is that the example doesn't set any verbosity level and also doesn't enable EnvFilter.

So maybe either with_env_filter or with_max_level should be added to the example.