Regression: New `tracing-subscriber` breaks ANSI color and styling support

[ziemkowski]

Bug Report

The 0.3.20 release with PR #3368 attempts to disallow unsafe ANSI control characters, but escaping the ESC character disables all ANSI control sequences, making coloring and styling in logs now show escaped ANSI sequences.

It seems like the ANSI escape sequence character (\x1b ESC) should not be included in the list, as it also controls when colors and styles are honored.

If the desire is to escape all ANSI, could we change format().with_ansi() to something like format().with_dangerous_ansi() and disable the entire #3368 change?

Version

tracing v0.1.41 (*)
tracing-subscriber v0.3.20 (*)

Platform

Darwin adrian-personal 24.6.0 Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:55 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6031 arm64

Crates

tracing-subscriber

Description

I have hundreds (thousands?) of instances of colored-rs vars in my logs that now print escape sequences in color TTYs.

For example:

info!("This is red: {}", "color test".red());

now escapes the color sequence despite format().with_ansi(use_color):

This is red: \x1b[31mcolor test\x1b[0m

The PR description mentions "while preserving the ability for applications to deliberately include formatting in trusted contexts" but I didn't see a way to do this. If there is in fact a way, it should be better documented.

[ziemkowski]

Temporary workaround:

Locking the tracing-subcriber crate to 0.3.19 in Crate.toml fixes the issue:

tracing-subscriber = { version = "=0.3.19", features = ["env-filter"] }

[doroved]

I also encountered this problem, and I'm glad that it has already been discussed.

println!("\u{001b}[38;5;208mTEST\u{001b}[0m");
tracing::info!("\u{001b}[38;5;208mTEST\u{001b}[0m");

[stlyx]

Any solution to opt-out #3368 ?

[AdrianEddy]

I have the same issue, I'd like to be able to use the ANSI colors. I think the \x1b escape code should be whitelisted

[goulvenclech]

Same issue here!

[ziemkowski]

@carllerche have you seen this request to update your recent change?
cc @hawkw (since you approved #3368)

[ndevenish]

Frustrating! Pinned for now.

To clear my understanding: This patch discussed has completely disabled the ability to use colored logging output in tracing-subscriber? with_ansi(true) only controls whether the e.g. level name is output with a colour now?