Perfect color-eyre

color-eyre provides advanced ways to obtain BACKTRACE and SPANTRACE and is hard to ignore.

Let’s extend the official example by adding hooq’s pseudo trace.

Create a new project and set the following in Cargo.toml (replace hooq with the latest version):

[features]
default = ["capture-spantrace"]
capture-spantrace = []

[dependencies]
color-eyre = "0.6.5"
hooq = { path = "../../hooq" } # Please rewrite `hooq = "*"`
tracing = "0.1.43"
tracing-error = "0.2.1"
tracing-subscriber = { version = "0.3.22", features = ["env-filter"] }

We want color_eyre::eyre::WrapErr instead of ::eyre::WrapErr, so place hooq.toml next to Cargo.toml to override the import. Other settings inherit from the built‑in eyre flavor.

[eyre]
trait_uses = ["color_eyre::eyre::WrapErr"]

Write main.rs. use hooq::hooq; and annotate #[hooq(eyre)] above #[instrument] (we also add .without_time() to stabilize snapshots).

use color_eyre::Section;
use color_eyre::eyre::{Report, WrapErr};
use hooq::hooq;
use tracing::{info, instrument};

#[hooq(eyre)]
#[instrument]
fn main() -> Result<(), Report> {
    #[cfg(feature = "capture-spantrace")]
    install_tracing();

    color_eyre::install()?;

    read_config()
}

#[cfg(feature = "capture-spantrace")]
fn install_tracing() {
    use tracing_error::ErrorLayer;
    use tracing_subscriber::prelude::*;
    use tracing_subscriber::{EnvFilter, fmt};

    let fmt_layer = fmt::layer().with_target(false).without_time();
    let filter_layer = EnvFilter::try_from_default_env()
        .or_else(|_| EnvFilter::try_new("info"))
        .unwrap();

    tracing_subscriber::registry()
        .with(filter_layer)
        .with(fmt_layer)
        .with(ErrorLayer::default())
        .init();
}

#[hooq(eyre)]
#[instrument]
fn read_file(path: &str) -> Result<(), Report> {
    info!("Reading file");
    std::fs::read_to_string(path).map(drop)
}

#[hooq(eyre)]
#[instrument]
fn read_config() -> Result<(), Report> {
    read_file("fake_file")
        .wrap_err("Unable to read config")
        .suggestion("try using a file that exists next time")
}

Run with RUST_LIB_BACKTRACE=1 to also see the BACKTRACE:

Error: 
   0: [mdbook-source-code/recipe-color-eyre/src/main.rs:14:5]
        14>    read_config()
          |
   1: [mdbook-source-code/recipe-color-eyre/src/main.rs:45:5]
        45>    read_file("fake_file")
        46|        .wrap_err("Unab..nfig")
        47|        .suggestion("try ..time")
          |
   2: Unable to read config
   3: [mdbook-source-code/recipe-color-eyre/src/main.rs:39:5]
        39>    std::fs::read_to_string(path).map(drop)
          |
   4: No such file or directory (os error 2)

Location:
   mdbook-source-code/recipe-color-eyre/src/main.rs:39

  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ SPANTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

   0: recipe_color_eyre::read_file with path="fake_file"
      at mdbook-source-code/recipe-color-eyre/src/main.rs:36
   1: recipe_color_eyre::read_config
      at mdbook-source-code/recipe-color-eyre/src/main.rs:43

  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BACKTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
                                ⋮ 4 frames hidden ⋮                               
   5: <E as eyre::context::ext::StdError>::ext_report::h0e9fcf40b567f05e
      at /home/USER/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/eyre-0.6.12/src/context.rs:26
                                 ⋮ 1 frame hidden ⋮                               
   7: recipe_color_eyre::read_file::h74782b4bb409e5a9
      at /home/USER/workspace/hooq/mdbook-source-code/recipe-color-eyre/src/main.rs:39
   8: recipe_color_eyre::read_config::h8139da57eb93337e
      at /home/USER/workspace/hooq/mdbook-source-code/recipe-color-eyre/src/main.rs:45
   9: recipe_color_eyre::main::h9c27f45de169a3be
      at /home/USER/workspace/hooq/mdbook-source-code/recipe-color-eyre/src/main.rs:14
  10: core::ops::function::FnOnce::call_once::h724113526cc98cab
      at /home/USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250
  11: std::sys::backtrace::__rust_begin_short_backtrace::h9e20a34286867e4d
      at /home/USER/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/backtrace.rs:158
                                ⋮ 14 frames hidden ⋮                              

Suggestion: try using a file that exists next time

Run with COLORBT_SHOW_HIDDEN=1 environment variable to disable frame filtering.
Run with RUST_BACKTRACE=full to include source snippets.

This is likely the most detailed output.