log: remove deprecated env_logger and trace_logger APIs (#2771)

Removing the `env_logger` feature in order to address GHSA-g98v-hv3f-hcfr.

In addition, this PR also removes the deprecated `trace_logger` module, in
preparation for an upcoming v0.2.0 of `tracing-log`.

For additional details on the approach, please refer to #2750. Note that this
PR depends on #2770, so this PR will temporarily have more commits 
than intended. 
---------

Co-authored-by: Eliza Weisman <eliza@buoyant.io>

examples/Cargo.toml

@@ -19,7 +19,6 @@ tracing-tower = { version = "0.1.0", path = "../tracing-tower" }
 tracing-subscriber = { path = "../tracing-subscriber", version = "0.3.0", features = ["json", "env-filter"] }
 tracing-futures = { version = "0.2.1", path = "../tracing-futures", features = ["futures-01"] }
 tracing-attributes = { path = "../tracing-attributes", version = "0.1.22" }
-tracing-log = { path = "../tracing-log", version = "0.1.3", features = ["env_logger"] }
 tracing-serde = { path = "../tracing-serde" }
 tracing-appender = { path = "../tracing-appender", version = "0.2.0" }
 tracing-journald = { path = "../tracing-journald" }

tracing-log/Cargo.toml

@@ -18,17 +18,15 @@ readme = "README.md"
 rust-version = "1.56.0"
 
 [features]
-default = ["log-tracer", "trace-logger", "std"]
+default = ["log-tracer", "std"]
 std = ["log/std"]
 log-tracer = []
-trace-logger = []
 interest-cache = ["lru", "ahash"]
 
 [dependencies]
 tracing-core = { path = "../tracing-core", version = "0.1.28"}
 log = { version = "0.4.17" }
 once_cell = "1.13.0"
-env_logger = { version = "0.8.4", optional = true }
 lru = { version = "0.7.7", optional = true }
 ahash = { version = "0.7.6", optional = true }
 

tracing-log/README.md

@@ -43,8 +43,6 @@ This crate provides:
 - [`AsTrace`] and [`AsLog`] traits for converting between `tracing` and `log` types.
 - [`LogTracer`], a [`log::Log`] implementation that consumes [`log::Record`]s
   and outputs them as [`tracing::Event`]s.
-- An [`env_logger`] module, with helpers for using the [`env_logger` crate]
-  with `tracing` (optional, enabled by the `env_logger` feature).
 
 [`tracing`]: https://crates.io/crates/tracing
 [`log`]: https://crates.io/crates/log

tracing-log/src/lib.rs

@@ -13,8 +13,6 @@
 //! - [`AsTrace`] and [`AsLog`] traits for converting between `tracing` and `log` types.
 //! - [`LogTracer`], a [`log::Log`] implementation that consumes [`log::Record`]s
 //!   and outputs them as [`tracing::Event`].
-//! - An [`env_logger`] module, with helpers for using the [`env_logger` crate]
-//!   with `tracing` (optional, enabled by the `env-logger` feature).
 //!
 //! *Compiler support: [requires `rustc` 1.56+][msrv]*
 //!
@@ -57,23 +55,20 @@
 //!
 //! ## Caution: Mixing both conversions
 //!
-//! Note that logger implementations that convert log records to trace events
+//! Note that `log::Logger` implementations that convert log records to trace events
 //! should not be used with `Subscriber`s that convert trace events _back_ into
-//! log records (such as the `TraceLogger`), as doing so will result in the
-//! event recursing between the subscriber and the logger forever (or, in real
-//! life, probably overflowing the call stack).
+//! `log` records, as doing so will result in the event recursing between the subscriber
+//! and the logger forever (or, in real life, probably overflowing the call stack).
 //!
 //! If the logging of trace events generated from log records produced by the
 //! `log` crate is desired, either the `log` crate should not be used to
 //! implement this logging, or an additional layer of filtering will be
 //! required to avoid infinitely converting between `Event` and `log::Record`.
 //!
-//! # Feature Flags
-//! * `trace-logger`: enables an experimental `log` subscriber, deprecated since
-//!   version 0.1.1.
+//! ## Feature Flags
+//!
+//! * `std`: enables features that require the Rust standard library (on by default)
 //! * `log-tracer`: enables the `LogTracer` type (on by default)
-//! * `env_logger`: enables the `env_logger` module, with helpers for working
-//!   with the [`env_logger` crate].
 //! * `interest-cache`: makes it possible to configure an interest cache for
 //!   logs emitted through the `log` crate (see [`Builder::with_interest_cache`]); requires `std`
 //!
@@ -94,7 +89,6 @@
 //! [`init`]: LogTracer::init
 //! [`init_with_filter`]: LogTracer::init_with_filter
 //! [`tracing`]: https://crates.io/crates/tracing
-//! [`env_logger` crate]: https://crates.io/crates/env-logger
 //! [`tracing::Subscriber`]: https://docs.rs/tracing/latest/tracing/trait.Subscriber.html
 //! [`Subscriber`]: https://docs.rs/tracing/latest/tracing/trait.Subscriber.html
 //! [`tracing::Event`]: https://docs.rs/tracing/latest/tracing/struct.Event.html
@@ -143,33 +137,11 @@ use tracing_core::{
 #[cfg_attr(docsrs, doc(cfg(feature = "log-tracer")))]
 pub mod log_tracer;
 
-#[cfg(feature = "trace-logger")]
-#[cfg_attr(docsrs, doc(cfg(feature = "trace-logger")))]
-pub mod trace_logger;
-
 #[cfg(feature = "log-tracer")]
 #[cfg_attr(docsrs, doc(cfg(feature = "log-tracer")))]
 #[doc(inline)]
 pub use self::log_tracer::LogTracer;
 
-#[cfg(feature = "trace-logger")]
-#[cfg_attr(docsrs, doc(cfg(feature = "trace-logger")))]
-#[deprecated(
-    since = "0.1.1",
-    note = "use the `tracing` crate's \"log\" feature flag instead"
-)]
-#[allow(deprecated)]
-#[doc(inline)]
-pub use self::trace_logger::TraceLogger;
-
-#[cfg(feature = "env_logger")]
-#[cfg_attr(docsrs, doc(cfg(feature = "env_logger")))]
-#[deprecated(
-    since = "0.1.4",
-    note = "use `tracing-subscriber`'s `fmt::Subscriber` instead"
-)]
-pub mod env_logger;
-
 pub use log;
 
 #[cfg(all(feature = "interest-cache", feature = "log-tracer", feature = "std"))]