log

What's Changed

• doc: Add context-logger utility to README by @alekseysidorov in #735
• Add alloc support for boxed loggers by @malezjaa in #737

New Contributors

• @alekseysidorov made their first contribution in #735
• @malezjaa made their first contribution in #737

Full Changelog: 0.4.33...0.4.34

What's Changed

• Fixed key comparison by @matteo-zeggiotti-ok in #732

New Contributors

• @matteo-zeggiotti-ok made their first contribution in #732

Full Changelog: 0.4.32...0.4.33

What's Changed

• Support Value -> string conversions with kv + std features instead of kv_std by @tisonkun in #729
• Prepare for 0.4.32 release by @KodrAus in #730

Full Changelog: 0.4.31...0.4.32

What's Changed

• Support Value -> string conversions with kv + std features instead of kv_std by @tisonkun in https://github.com/rust-lang/log/pull/729

Full Changelog: https://github.com/rust-lang/log/compare/0.4.31...0.4.32

What's Changed

• fix typos in kv compile errors and log documentation by @Isvane in #726
• Leverage static str key when possible by @tisonkun in #727
• Prepare for 0.4.31 release by @KodrAus in #728

New Contributors

• @Isvane made their first contribution in #726

Full Changelog: 0.4.30...0.4.31

What's Changed

• Leverage static str key when possible by @tisonkun in https://github.com/rust-lang/log/pull/727

New Contributors

• @Isvane made their first contribution in https://github.com/rust-lang/log/pull/726

Full Changelog: https://github.com/rust-lang/log/compare/0.4.30...0.4.31

What's Changed

• Support capturing of std::net types by @KodrAus in #724

New Contributors

• @V0ldek made their first contribution in #720
• @woodruffw made their first contribution in #723

Full Changelog: 0.4.29...0.4.30

Notable Changes

• MSRV is bumped to 1.71.0 in #723

What's Changed

• Support capturing of std::net types by @KodrAus in https://github.com/rust-lang/log/pull/724

New Contributors

• @V0ldek made their first contribution in https://github.com/rust-lang/log/pull/720
• @woodruffw made their first contribution in https://github.com/rust-lang/log/pull/723

Full Changelog: https://github.com/rust-lang/log/compare/0.4.29...0.4.30

Notable Changes

• MSRV is bumped to 1.71.0 in https://github.com/rust-lang/log/pull/723

MSRV

This release increases log's MSRV from 1.61.0 to 1.68.0.

What's Changed

• docs: Add missing impls from README.md by @AldaronLau in #703
• Point to new URLs for favicon and logo by @AldaronLau in #704
• perf: reduce llvm-lines of FromStr for Level and LevelFilter by @dishmaker in #709
• Replace serde with serde_core by @Thomasdezeeuw in #712
• Fix clippy lints by @Thomasdezeeuw in #713
• Use GitHub Actions to install Rust and cargo-hack by @Thomasdezeeuw in #715
• Exclude old unstable_kv features from testing matrix by @Thomasdezeeuw in #716
• Fix up CI by @KodrAus in #718
• Prepare for 0.4.29 release by @KodrAus in #719

New Contributors

• @AldaronLau made their first contribution in #703
• @dishmaker made their first contribution in #709

Full Changelog: 0.4.28...0.4.29

What's Changed

• perf: reduce llvm-lines of FromStr for Level and LevelFilter by @dishmaker in https://github.com/rust-lang/log/pull/709
• Replace serde with serde_core by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/712

New Contributors

• @AldaronLau made their first contribution in https://github.com/rust-lang/log/pull/703
• @dishmaker made their first contribution in https://github.com/rust-lang/log/pull/709

Full Changelog: https://github.com/rust-lang/log/compare/0.4.28...0.4.29

What's Changed

• ci: drop really old trick and ensure MSRV for all feature combo by @tisonkun in #676
• chore: fix some typos in comment by @xixishidibei in #677
• Unhide #[derive(Debug)] in example by @ZylosLumen in #688
• Chore: delete compare_exchange method for AtomicUsize on platforms without atomics by @HaoliangXu in #690
• Add increment_severity() and decrement_severity() methods for Level and LevelFilter by @nebkor in #692
• Prepare for 0.4.28 release by @KodrAus in #695

New Contributors

• @xixishidibei made their first contribution in #677
• @ZylosLumen made their first contribution in #688
• @HaoliangXu made their first contribution in #690
• @nebkor made their first contribution in #692

Full Changelog: 0.4.27...0.4.28

What's Changed

• ci: drop really old trick and ensure MSRV for all feature combo by @tisonkun in https://github.com/rust-lang/log/pull/676
• Chore: delete compare_exchange method for AtomicUsize on platforms without atomics by @HaoliangXu in https://github.com/rust-lang/log/pull/690
• Add increment_severity() and decrement_severity() methods for Level and LevelFilter by @nebkor in https://github.com/rust-lang/log/pull/692

What's Changed

• A few minor lint fixes by @nyurik in #671
• Enable clippy support for format-like macros by @nyurik in #665
• Add an optional logger param by @tisonkun in #664
• Pass global logger by value, supplied logger by ref by @KodrAus in #673
• Prepare for 0.4.27 release by @KodrAus in #674

Full Changelog: 0.4.26...0.4.27

What's Changed

• A few minor lint fixes by @nyurik in https://github.com/rust-lang/log/pull/671
• Enable clippy support for format-like macros by @nyurik in https://github.com/rust-lang/log/pull/665
• Add an optional logger param by @tisonkun in https://github.com/rust-lang/log/pull/664
• Pass global logger by value, supplied logger by ref by @KodrAus in https://github.com/rust-lang/log/pull/673

Full Changelog: https://github.com/rust-lang/log/compare/0.4.26...0.4.27

What's Changed

• Derive Clone for kv::Value by @SpriteOvO in #668
• Add spdlog-rs link to crate doc by @SpriteOvO in #669
• Prepare for 0.4.26 release by @KodrAus in #670

Full Changelog: 0.4.25...0.4.26

What's Changed

• Derive Clone for kv::Value by @SpriteOvO in https://github.com/rust-lang/log/pull/668
• Add spdlog-rs link to crate doc by @SpriteOvO in https://github.com/rust-lang/log/pull/669

Full Changelog: https://github.com/rust-lang/log/compare/0.4.25...0.4.26

What's Changed

• Revert loosening of kv cargo features by @KodrAus in #662
• Prepare for 0.4.25 release by @KodrAus in #663

Full Changelog: 0.4.24...0.4.25

What's Changed

• Revert loosening of kv cargo features by @KodrAus in https://github.com/rust-lang/log/pull/662

Full Changelog: https://github.com/rust-lang/log/compare/0.4.24...0.4.25

What's Changed

• Fix up kv feature activation by @KodrAus in https://github.com/rust-lang/log/pull/659

Full Changelog: https://github.com/rust-lang/log/compare/0.4.23...0.4.24

What's Changed

• Fix some typos by @Kleinmarb in https://github.com/rust-lang/log/pull/637
• Add logforth to implementation by @tisonkun in https://github.com/rust-lang/log/pull/638
• Add spdlog-rs link to README by @SpriteOvO in https://github.com/rust-lang/log/pull/639
• Add correct lifetime to kv::Value::to_borrowed_str by @stevenroose in https://github.com/rust-lang/log/pull/643
• docs: Add logforth as an impl by @tisonkun in https://github.com/rust-lang/log/pull/642
• Add clang_log implementation by @DDAN-17 in https://github.com/rust-lang/log/pull/646
• Bind lifetimes of &str returned from Key by the lifetime of 'k rather than the lifetime of the Key struct by @gbbosak in https://github.com/rust-lang/log/pull/648
• Fix up key lifetimes and add method to try get a borrowed key by @KodrAus in https://github.com/rust-lang/log/pull/653
• Add Ftail implementation by @tjardoo in https://github.com/rust-lang/log/pull/652

New Contributors

• @Kleinmarb made their first contribution in https://github.com/rust-lang/log/pull/637
• @tisonkun made their first contribution in https://github.com/rust-lang/log/pull/638
• @SpriteOvO made their first contribution in https://github.com/rust-lang/log/pull/639
• @stevenroose made their first contribution in https://github.com/rust-lang/log/pull/643
• @DDAN-17 made their first contribution in https://github.com/rust-lang/log/pull/646
• @gbbosak made their first contribution in https://github.com/rust-lang/log/pull/648
• @tjardoo made their first contribution in https://github.com/rust-lang/log/pull/652

Full Changelog: https://github.com/rust-lang/log/compare/0.4.22...0.4.23

What's Changed

• Add some clarifications to the library docs by @KodrAus in https://github.com/rust-lang/log/pull/620
• Add links to colog crate by @chrivers in https://github.com/rust-lang/log/pull/621
• adding line_number test + updating some testing infrastructure by @DIvkov575 in https://github.com/rust-lang/log/pull/619
• Clarify the actual set of functions that can race in _racy variants by @KodrAus in https://github.com/rust-lang/log/pull/623
• Replace deprecated std::sync::atomic::spin_loop_hint() by @Catamantaloedis in https://github.com/rust-lang/log/pull/625
• Check usage of max_level features by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/627
• Remove unneeded import by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/628
• Loosen orderings for logger initialization in https://github.com/rust-lang/log/pull/632. Originally by @pwoolcoc in https://github.com/rust-lang/log/pull/599
• Use Location::caller() for file and line info in https://github.com/rust-lang/log/pull/633. Originally by @Cassy343 in https://github.com/rust-lang/log/pull/520

New Contributors

• @chrivers made their first contribution in https://github.com/rust-lang/log/pull/621
• @DIvkov575 made their first contribution in https://github.com/rust-lang/log/pull/619
• @Catamantaloedis made their first contribution in https://github.com/rust-lang/log/pull/625

Full Changelog: https://github.com/rust-lang/log/compare/0.4.21...0.4.22

What's Changed

• Minor clippy nits by @nyurik in https://github.com/rust-lang/log/pull/578
• Simplify Display impl by @nyurik in https://github.com/rust-lang/log/pull/579
• Set all crates to 2021 edition by @nyurik in https://github.com/rust-lang/log/pull/580
• Various changes based on review by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/583
• Fix typo in file_static() method doc by @dimo414 in https://github.com/rust-lang/log/pull/590
• Specialize empty key value pairs by @EFanZh in https://github.com/rust-lang/log/pull/576
• Fix incorrect lifetime in Value::to_str() by @peterjoel in https://github.com/rust-lang/log/pull/587
• Remove some API of the key-value feature by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/585
• Add logcontrol-log and log-reload by @swsnr in https://github.com/rust-lang/log/pull/595
• Add Serialization section to kv::Value docs by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/593
• Rename Value::to_str to to_cow_str by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/592
• Clarify documentation and simplify initialization of STATIC_MAX_LEVEL by @ptosi in https://github.com/rust-lang/log/pull/594
• Update docs to 2021 edition, test by @nyurik in https://github.com/rust-lang/log/pull/577
• Add "alterable_logger" link to README.md by @brummer-simon in https://github.com/rust-lang/log/pull/589
• Normalize line ending by @EFanZh in https://github.com/rust-lang/log/pull/602
• Remove ok_or in favor of Option::ok_or by @AngelicosPhosphoros in https://github.com/rust-lang/log/pull/607
• Use Acquire ordering for initialization check by @AngelicosPhosphoros in https://github.com/rust-lang/log/pull/610
• Get structured logging API ready for stabilization by @KodrAus in https://github.com/rust-lang/log/pull/613

New Contributors

• @nyurik made their first contribution in https://github.com/rust-lang/log/pull/578
• @dimo414 made their first contribution in https://github.com/rust-lang/log/pull/590
• @peterjoel made their first contribution in https://github.com/rust-lang/log/pull/587
• @ptosi made their first contribution in https://github.com/rust-lang/log/pull/594
• @brummer-simon made their first contribution in https://github.com/rust-lang/log/pull/589
• @AngelicosPhosphoros made their first contribution in https://github.com/rust-lang/log/pull/607

• Remove rustversion dev-dependency by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/568
• Remove local_inner_macros usage by @EFanZh in https://github.com/rust-lang/log/pull/570

• Use target_has_atomic instead of the old atomic_cas cfg by @GuillaumeGomez in https://github.com/rust-lang/log/pull/555
• Put MSRV into Cargo.toml by @est31 in https://github.com/rust-lang/log/pull/557

• fix Markdown links (again) by @hellow554 in https://github.com/rust-lang/log/pull/513
• add cargo doc to workflow by @hellow554 in https://github.com/rust-lang/log/pull/515
• Apply Clippy lints by @hellow554 in https://github.com/rust-lang/log/pull/516
• Replace ad-hoc eq_ignore_ascii_case with slice::eq_ignore_ascii_case by @glandium in https://github.com/rust-lang/log/pull/519
• fix up windows targets by @KodrAus in https://github.com/rust-lang/log/pull/528
• typo fix by @jiangying000 in https://github.com/rust-lang/log/pull/529
• Remove dependency on cfg_if by @EriKWDev in https://github.com/rust-lang/log/pull/536
• GitHub Workflows security hardening by @sashashura in https://github.com/rust-lang/log/pull/538
• Fix build status badge by @atouchet in https://github.com/rust-lang/log/pull/539
• Add call_logger to the documentation by @a1ecbr0wn in https://github.com/rust-lang/log/pull/547
• Use stable internals for key-value API by @KodrAus in https://github.com/rust-lang/log/pull/550
• Change wording of list of implementations by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/553
• Add std-logger to list of implementations by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/554
• Add set_max_level_racy and gate set_max_level by @djkoloski in https://github.com/rust-lang/log/pull/544
• [doc] src/lib.rs : prefix an unused variable with an underscore by @OccupyMars2025 in https://github.com/rust-lang/log/pull/561
• [doc] src/macros.rs : correct grammar errors of an example in lib documentation by @OccupyMars2025 in https://github.com/rust-lang/log/pull/562

• Update kv_unstable internal dependencies.

• Fix a conflict with unqualified Option use in macros.

• Silence a warning about the deprecated spin_loop_hint.
• Relax ordering in the atomic set_max_level call.
• Add thumbv4t-none-eabi to targets that don't support atomics
• Allow levels to be iterated over.
• Implement Log on some common wrapper types.
• Improvements to test coverage.
• Improvements to documentation.
• Add key-value support to the log! macros.
• Tighten kv_unstable internal dependencies, so they don't bump past their current alpha.
• Add a simple visit API to kv_unstable.
• Support NonZero* integers as values in structured logging
• Support static strings as keys in structured logging

• Remove the __private_api_log_lit special case.
• Fixed incorrect combination of kv_unstable and std features causing compile failures.
• Remove unstable Value::to_* conversions that were incorrectly using as.
• Rename unstable Value::to_error to Value::to_borrowed_error.

• This is the same as 0.4.11, except with a kv_unstable_std feature added to aid migrating current dependents to 0.4.14 (which was originally going to be 0.4.13 until it was decided to create a patch from 0.4.11 to minimize disruption).

New

• Support platforms without atomics by racing instead of failing to compile
• Implement Log for Box<T: Log>
• Update cfg-if to 1.0
• Internal reworks of the structured logging API. Removed the Fill API and added source::as_map and source::as_list to easily serialize a Source as either a map of {key: value, ..} or as a list of [(key, value), ..].

Fixed

• Fixed deserialization of LevelFilter to use their u64 index variants

New

• Support coercing structured values into concrete types.
• Reference the win_dbg_logger in the readme.

Fixed

• Updates a few deprecated items used internally.
• Fixed issues in docs and expands sections.
• Show the correct build badge in the readme.
• Fix up a possible inference breakage with structured value errors.
• Respect formatting flags in structured value formatting.

Fixed

• Fixed the log! macros, so they work in expression context (this regressed in 0.4.9, which has been yanked).

Minimum Supported Rust Version

This release bumps the minimum compiler version to 1.31.0. This was mainly needed for cfg-if, but between 1.16.0 and 1.31.0 there are a lot of language and library improvements we now take advantage of.

New

• Unstable support for capturing key-value pairs in a record using the log! macros

Improved

• Better documentation for max level filters.
• Internal updates to line up with bumped MSRV

New

• Support attempting to get Record fields as static strings.

New

• Support for embedded environments with thread-unsafe initialization.
• Initial unstable support for capturing structured data under the kv_unstable feature gate. This new API doesn't affect existing users and may change in future patches (so those changes may not appear in the changelog until it stabilizes).

Improved

• Docs for using log with the 2018 edition.
• Error messages for macros missing arguments.

Improved

• Support 2018-style macro import for the log_enabled! macro.

Improved

• Make log's internal helper macros less likely to conflict with user-defined macros.

Improved

• Support 2018-style imports of the log macros.

Improved

• More code generation improvements.

Improved

• Log invocations now generate less code.

Fixed

• Example Logger implementations now properly set the max log level.

Fixed

• Some doc links were fixed.

The changes in this release include cleanup of some obscure functionality and a more robust public API designed to support bridges to other logging systems, and provide more flexibility to new features in the future.

Compatibility

Vast portions of the Rust ecosystem use the 0.3.x release series of log, and we don't want to force the community to go through the pain of upgrading every crate to 0.4.x at the exact same time. Along with 0.4.0, we've published a new 0.3.9 release which acts as a "shim" over 0.4.0. This will allow crates using either version to coexist without losing messages from one side or the other.

There is one caveat - a log message generated by a crate using 0.4.x but consumed by a logging implementation using 0.3.x will not have a file name or module path. Applications affected by this can upgrade their logging implementations to one using 0.4.x to avoid losing this information. The other direction does not lose any information, fortunately!

TL;DR Libraries should feel comfortable upgrading to 0.4.0 without treating that as a breaking change. Applications may need to update their logging implementation (e.g. env-logger) to a newer version using log 0.4.x to avoid losing module and file information.

New

• The crate is now no_std by default.
• Level and LevelFilter now implement Serialize and Deserialize when the serde feature is enabled.
• The Record and Metadata types can now be constructed by third-party code via a builder API.
• The logger free function returns a reference to the logger implementation. This, along with the ability to construct Records, makes it possible to bridge from another logging framework to this one without digging into the private internals of the crate. The standard error! warn!, etc., macros now exclusively use the public API of the crate rather than "secret" internal APIs.
• Log::flush has been added to allow crates to tell the logging implementation to ensure that all "in flight" log events have been persisted. This can be used, for example, just before an application exits to ensure that asynchronous log sinks finish their work.

Removed

• The shutdown and shutdown_raw functions have been removed. Supporting shutdown significantly complicated the implementation and imposed a performance cost on each logging operation.
• The log_panics function and its associated nightly Cargo feature have been removed. Use the log-panics instead.

Changed

• The Log prefix has been removed from type names. For example, LogLevelFilter is now LevelFilter, and LogRecord is now Record.
• The MaxLogLevelFilter object has been removed in favor of a set_max_level free function.
• The set_logger free functions have been restructured. The logger is now directly passed to the functions rather than a closure which returns the logger. set_logger now takes a &'static Log and is usable in no_std contexts in place of the old set_logger_raw. set_boxed_logger is a convenience function which takes a Box<Log> but otherwise acts like set_logger. It requires the std feature.
• The file and module_path values in Record no longer have the 'static lifetime to support integration with other logging frameworks that don't provide a 'static lifetime for the equivalent values.
• The file, line, and module_path values in Record are now Options to support integration with other logging frameworks that don't provide those values.

In the Future

• We're looking to add support for structured logging - the inclusion of extra key-value pairs of information in a log event in addition to the normal string message. This should be able to be added in a backwards compatible manner to the 0.4.x series when the design is worked out.