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|
//! This crate allows tools to enable rust logging without having to magically
//! match rustc's tracing crate version.
//!
//! For example if someone is working on rustc_ast and wants to write some
//! minimal code against it to run in a debugger, with access to the `debug!`
//! logs emitted by rustc_ast, that can be done by writing:
//!
//! ```toml
//! [dependencies]
//! rustc_ast = { path = "../rust/compiler/rustc_ast" }
//! rustc_log = { path = "../rust/compiler/rustc_log" }
//! rustc_span = { path = "../rust/compiler/rustc_span" }
//! ```
//!
//! ```
//! fn main() {
//! rustc_log::init_env_logger("LOG").unwrap();
//!
//! let edition = rustc_span::edition::Edition::Edition2021;
//! rustc_span::create_session_globals_then(edition, || {
//! /* ... */
//! });
//! }
//! ```
//!
//! Now `LOG=debug cargo run` will run your minimal main.rs and show
//! rustc's debug logging. In a workflow like this, one might also add
//! `std::env::set_var("LOG", "debug")` to the top of main so that `cargo
//! run` by itself is sufficient to get logs.
//!
//! The reason rustc_log is a tiny separate crate, as opposed to exposing the
//! same things in rustc_driver only, is to enable the above workflow. If you
//! had to depend on rustc_driver in order to turn on rustc's debug logs, that's
//! an enormously bigger dependency tree; every change you make to rustc_ast (or
//! whichever piece of the compiler you are interested in) would involve
//! rebuilding all the rest of rustc up to rustc_driver in order to run your
//! main.rs. Whereas by depending only on rustc_log and the few crates you are
//! debugging, you can make changes inside those crates and quickly run main.rs
//! to read the debug logs.
#![deny(rustc::untranslatable_diagnostic)]
#![deny(rustc::diagnostic_outside_of_impl)]
#![feature(is_terminal)]
use std::env::{self, VarError};
use std::fmt::{self, Display};
use std::io::{self, IsTerminal};
use tracing_core::{Event, Subscriber};
use tracing_subscriber::filter::{Directive, EnvFilter, LevelFilter};
use tracing_subscriber::fmt::{
format::{self, FormatEvent, FormatFields},
FmtContext,
};
use tracing_subscriber::layer::SubscriberExt;
pub fn init_env_logger(env: &str) -> Result<(), Error> {
let filter = match env::var(env) {
Ok(env) => EnvFilter::new(env),
_ => EnvFilter::default().add_directive(Directive::from(LevelFilter::WARN)),
};
let color_logs = match env::var(String::from(env) + "_COLOR") {
Ok(value) => match value.as_ref() {
"always" => true,
"never" => false,
"auto" => stderr_isatty(),
_ => return Err(Error::InvalidColorValue(value)),
},
Err(VarError::NotPresent) => stderr_isatty(),
Err(VarError::NotUnicode(_value)) => return Err(Error::NonUnicodeColorValue),
};
let verbose_entry_exit = match env::var_os(String::from(env) + "_ENTRY_EXIT") {
None => false,
Some(v) => &v != "0",
};
let layer = tracing_tree::HierarchicalLayer::default()
.with_writer(io::stderr)
.with_indent_lines(true)
.with_ansi(color_logs)
.with_targets(true)
.with_verbose_exit(verbose_entry_exit)
.with_verbose_entry(verbose_entry_exit)
.with_indent_amount(2);
#[cfg(parallel_compiler)]
let layer = layer.with_thread_ids(true).with_thread_names(true);
let subscriber = tracing_subscriber::Registry::default().with(filter).with(layer);
match env::var(format!("{env}_BACKTRACE")) {
Ok(str) => {
let fmt_layer = tracing_subscriber::fmt::layer()
.with_writer(io::stderr)
.without_time()
.event_format(BacktraceFormatter { backtrace_target: str });
let subscriber = subscriber.with(fmt_layer);
tracing::subscriber::set_global_default(subscriber).unwrap();
}
Err(_) => {
tracing::subscriber::set_global_default(subscriber).unwrap();
}
};
Ok(())
}
struct BacktraceFormatter {
backtrace_target: String,
}
impl<S, N> FormatEvent<S, N> for BacktraceFormatter
where
S: Subscriber + for<'a> tracing_subscriber::registry::LookupSpan<'a>,
N: for<'a> FormatFields<'a> + 'static,
{
fn format_event(
&self,
_ctx: &FmtContext<'_, S, N>,
mut writer: format::Writer<'_>,
event: &Event<'_>,
) -> fmt::Result {
let target = event.metadata().target();
if !target.contains(&self.backtrace_target) {
return Ok(());
}
let backtrace = std::backtrace::Backtrace::capture();
writeln!(writer, "stack backtrace: \n{:?}", backtrace)
}
}
pub fn stdout_isatty() -> bool {
io::stdout().is_terminal()
}
pub fn stderr_isatty() -> bool {
io::stderr().is_terminal()
}
#[derive(Debug)]
pub enum Error {
InvalidColorValue(String),
NonUnicodeColorValue,
}
impl std::error::Error for Error {}
impl Display for Error {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Error::InvalidColorValue(value) => write!(
formatter,
"invalid log color value '{value}': expected one of always, never, or auto",
),
Error::NonUnicodeColorValue => write!(
formatter,
"non-Unicode log color value: expected one of always, never, or auto",
),
}
}
}
|
