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# Change Log
## [Unreleased]
## [0.4.20] - 2023-07-11
## [0.4.19] - 2023-06-10
* Use target_has_atomic instead of the old atomic_cas cfg by @GuillaumeGomez in https://github.com/rust-lang/log/pull/555
## [0.4.18] - 2023-05-28
* Replace ad-hoc eq_ignore_ascii_case with slice::eq_ignore_ascii_case by @glandium in https://github.com/rust-lang/log/pull/519
* 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
## [0.4.17] - 2022-04-29
* Update `kv_unstable` internal dependencies.
## [0.4.16] - 2022-03-22
* Fix a conflict with unqualified `Option` use in macros.
## [0.4.15] - 2022-02-23
* 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
## [0.4.14] - 2021-01-27
* 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`.
## [0.4.13] - 2021-01-11
* 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).
## [0.4.12] - 2020-12-24
### 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
## [0.4.11] - 2020-07-09
### 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.
## [0.4.10] - 2019-12-16 (yanked)
### Fixed
* Fixed the `log!` macros so they work in expression context (this regressed in `0.4.9`, which has been yanked).
## [0.4.9] - 2019-12-12 (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
## [0.4.8] - 2019-07-28
### New
* Support attempting to get `Record` fields as static strings.
## [0.4.7] - 2019-07-06
### 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.
## [0.4.6] - 2018-10-27
### Improved
* Support 2018-style macro import for the `log_enabled!` macro.
## [0.4.5] - 2018-09-03
### Improved
* Make `log`'s internal helper macros less likely to conflict with user-defined
macros.
## [0.4.4] - 2018-08-17
### Improved
* Support 2018-style imports of the log macros.
## [0.4.3] - 2018-06-29
### Improved
* More code generation improvements.
## [0.4.2] - 2018-06-05
### Improved
* Log invocations now generate less code.
### Fixed
* Example Logger implementations now properly set the max log level.
## [0.4.1] - 2017-12-30
### Fixed
* Some doc links were fixed.
## [0.4.0] - 2017-12-24
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 `Record`s, 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
### 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 `Option`s 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.
## Older
Look at the [release tags] for information about older releases.