Route codegen error includes literal escape codes

[robjwells]

Rocket Version

0.5.1

Operating System

macOS 12.7.6

Rust Toolchain Version

rustc 1.84.0 (9fc6b4312 2025-01-07)

What happened?

When encountering an (expected) error in route codegen with a mismatched path variable and function argument, the compiler error mesage includes terminal color escape codes as literal text, making the error message difficult to read.

Test Case

use rocket::{get, routes};

#[get("/hello/<name>")]
fn hello(other: &str) -> String {
    format!("Hello, {other}!")
}

#[rocket::launch]
fn rocket() -> rocket::Rocket<rocket::Build> {
    rocket::build().mount("/", routes![hello])
}

Log Output

❯ ROCKET_LOG_LEVEL=debug cargo build
   Compiling rocketroutetest v0.1.0 (/Users/robjwells/Desktop/rocketroutetest)
error: unused parameter
 --> src/main.rs:3:7
  |
3 | #[get("/hello/<name>")]
  |       ^^^^^^^^^^^^^^^

error: ␛[1;34m[␛[0m␛[1;32mnote␛[0m␛[1;34m] ␛[0m␛[1;39mexpected argument named `name` here␛[0m
 --> src/main.rs:4:9
  |
4 | fn hello(other: &str) -> String {
  |         ^^^^^^^^^^^^^

error[E0422]: cannot find struct, variant or union type `hello` in this scope
  --> src/main.rs:10:40
   |
10 |     rocket::build().mount("/", routes![hello])
   |                                        ^^^^^ not found in this scope

For more information about this error, try `rustc --explain E0422`.
error: could not compile `rocketroutetest` (bin "rocketroutetest") due to 3 previous errors

Additional Context

The source of the message is here:

Rocket/core/codegen/src/attribute/route/parse.rs

Lines 118 to 119 in f53611f

	let msg = format!("expected argument named `{}` here", param.name);
	let diag = param.span().error("unused parameter").span_note(args.span, msg);

This isn't affected by ROCKET_CLI_COLORS. There is no rocket.toml in the project. I don't have RUST_LOG or anything similar set in my shell env.

System Checks

• My bug report relates to functionality.
• I have tested against the latest Rocket release or a recent git commit.
• I have tested against the latest stable rustc toolchain.
• I was unable to find this issue previously reported.

[the10thWiz]

This looks like a fairly straight forward issue with proc-macro2-diagnostics. It's using yansi internally (outside of rocket) to add color the compile timeout output.

This appears to be related to the compiler version, since running on nightly solves this issue. I've reported this issue upstream (SergioBenitez/proc-macro2-diagnostics#11).