[trc] Flexi_logger trc outputs logs to a file with ANSI.

[12Saturn]

When I use the trc function of flexi_logger to output logs to a file locally, ANSI codes are present. Here is my use case.

use flexi_logger::{
    writers::FileLogWriter, Cleanup, Criterion,FileSpec, LogSpecification,Naming, WriteMode
};
use tracing::{error, info};

fn main() {
    let _keep_alive_handles = flexi_logger::trc::setup_tracing(
        LogSpecification::info(),
        None,
        FileLogWriter::builder(
            FileSpec::default()
                .directory("flexi_logger_example/logs")
                .basename("mylog")
                .use_timestamp(true),
        )
        .format(flexi_logger::default_format)
        .rotate(
            Criterion::Size(10_000_000),
            Naming::Timestamps,
            Cleanup::KeepLogFiles(7),
        )
        .write_mode(WriteMode::Async),
    )
    .unwrap();

    info!("Application started");
    error!("Something went wrong");
}

cargo.toml

flexi_logger = {version = "0.30.0", features = ["trc"]}
tracing = "0.1"

result:
�[2m2025-06-16T03:53:34.186399Z�[0m �[32m INFO�[0m �[2mflexi_logger_example�[0m�[2m:�[0m Application started �[2m2025-06-16T03:53:34.186429Z�[0m �[31mERROR�[0m �[2mflexi_logger_example�[0m�[2m:�[0m Something went wrong

expteced:
I hope that the flexi_logger trc input to the file does not contain ANSI. If there is any problem with my usage, please point it out. I would be extremely grateful.

[emabee]

I can reproduce this.
I'm not sure if this behavior was the same when flexi_logger's trc feature was released (back in 2021), maybe it was introduced by newer versions of tracing-subscriber. But there are possibilities to fix this.

Some background: tracing-subscriber requires a sink object that just implements std::io::Write - this means, the called object has no chance to influence the structure of what is written!

flexi_logger::trc::setup_tracinginitializes a tracing_subscriber::fmt::SubscriberBuilder<N = format::DefaultFields, E = format::Format<format::Full>, F = LevelFilter, W = fn() -> io::Stdout> which (at least meanwhile) offers capabilities to influence the log line formatting in many details.
I will provide an update that exposes these capabilities to the caller of setup_tracing.
You will then have to add a line to your code (it will be a breaking change, I guess).

[emabee]

The new version now requires an additional parameter to flexi_logger::setup_tracing().
In your case, it might be sufficient to add &flexi_logger::trc::FormatConfig::default(), since ANSI coloring is now switched off by default.