+Version 1.43.0 (2020-04-23)
+==========================
+
+Language
+--------
+- [Fixed using binary operations with `&{number}` (e.g. `&1.0`) not having
+ the type inferred correctly.][68129]
+- [Attributes such as `#[cfg()]` can now be used on `if` expressions.][69201]
+
+**Syntax only changes**
+- [Allow `type Foo: Ord` syntactically.][69361]
+- [Fuse associated and extern items up to defaultness.][69194]
+- [Syntactically allow `self` in all `fn` contexts.][68764]
+- [Merge `fn` syntax + cleanup item parsing.][68728]
+- [`item` macro fragments can be interpolated into `trait`s, `impl`s, and `extern` blocks.][69366]
+ For example, you may now write:
+ ```rust
+ macro_rules! mac_trait {
+ ($i:item) => {
+ trait T { $i }
+ }
+ }
+ mac_trait! {
+ fn foo() {}
+ }
+ ```
+
+These are still rejected *semantically*, so you will likely receive an error but
+these changes can be seen and parsed by macros and
+conditional compilation.
+
+
+Compiler
+--------
+- [You can now pass multiple lint flags to rustc to override the previous
+ flags.][67885] For example; `rustc -D unused -A unused-variables` denies
+ everything in the `unused` lint group except `unused-variables` which
+ is explicitly allowed. However, passing `rustc -A unused-variables -D unused` denies
+ everything in the `unused` lint group **including** `unused-variables` since
+ the allow flag is specified before the deny flag (and therefore overridden).
+- [rustc will now prefer your system MinGW libraries over its bundled libraries
+ if they are available on `windows-gnu`.][67429]
+- [rustc now buffers errors/warnings printed in JSON.][69227]
+
+Libraries
+---------
+- [`Arc<[T; N]>`, `Box<[T; N]>`, and `Rc<[T; N]>`, now implement
+ `TryFrom<Arc<[T]>>`,`TryFrom<Box<[T]>>`, and `TryFrom<Rc<[T]>>`
+ respectively.][69538] **Note** These conversions are only available when `N`
+ is `0..=32`.
+- [You can now use associated constants on floats and integers directly, rather
+ than having to import the module.][68952] e.g. You can now write `u32::MAX` or
+ `f32::NAN` with no imports.
+- [`u8::is_ascii` is now `const`.][68984]
+- [`String` now implements `AsMut<str>`.][68742]
+- [Added the `primitive` module to `std` and `core`.][67637] This module
+ reexports Rust's primitive types. This is mainly useful in macros
+ where you want avoid these types being shadowed.
+- [Relaxed some of the trait bounds on `HashMap` and `HashSet`.][67642]
+- [`string::FromUtf8Error` now implements `Clone + Eq`.][68738]
+
+Stabilized APIs
+---------------
+- [`Once::is_completed`]
+- [`f32::LOG10_2`]
+- [`f32::LOG2_10`]
+- [`f64::LOG10_2`]
+- [`f64::LOG2_10`]
+- [`iter::once_with`]
+
+Cargo
+-----
+- [You can now set config `[profile]`s in your `.cargo/config`, or through
+ your environment.][cargo/7823]
+- [Cargo will now set `CARGO_BIN_EXE_<name>` pointing to a binary's
+ executable path when running integration tests or benchmarks.][cargo/7697]
+ `<name>` is the name of your binary as-is e.g. If you wanted the executable
+ path for a binary named `my-program`you would use `env!("CARGO_BIN_EXE_my-program")`.
+
+Misc
+----
+- [Certain checks in the `const_err` lint were deemed unrelated to const
+ evaluation][69185], and have been moved to the `unconditional_panic` and
+ `arithmetic_overflow` lints.
+
+Compatibility Notes
+-------------------
+
+- [Having trailing syntax in the `assert!` macro is now a hard error.][69548] This
+ has been a warning since 1.36.0.
+- [Fixed `Self` not having the correctly inferred type.][69340] This incorrectly
+ led to some instances being accepted, and now correctly emits a hard error.
+
+[69340]: https://github.com/rust-lang/rust/pull/69340
+
+Internal Only
+-------------
+These changes provide no direct user facing benefits, but represent significant
+improvements to the internals and overall performance of `rustc` and
+related tools.
+
+- [All components are now built with `opt-level=3` instead of `2`.][67878]
+- [Improved how rustc generates drop code.][67332]
+- [Improved performance from `#[inline]`-ing certain hot functions.][69256]
+- [traits: preallocate 2 Vecs of known initial size][69022]
+- [Avoid exponential behaviour when relating types][68772]
+- [Skip `Drop` terminators for enum variants without drop glue][68943]
+- [Improve performance of coherence checks][68966]
+- [Deduplicate types in the generator witness][68672]
+- [Invert control in struct_lint_level.][68725]
+
+[67332]: https://github.com/rust-lang/rust/pull/67332/
+[67429]: https://github.com/rust-lang/rust/pull/67429/
+[67637]: https://github.com/rust-lang/rust/pull/67637/
+[67642]: https://github.com/rust-lang/rust/pull/67642/
+[67878]: https://github.com/rust-lang/rust/pull/67878/
+[67885]: https://github.com/rust-lang/rust/pull/67885/
+[68129]: https://github.com/rust-lang/rust/pull/68129/
+[68672]: https://github.com/rust-lang/rust/pull/68672/
+[68725]: https://github.com/rust-lang/rust/pull/68725/
+[68728]: https://github.com/rust-lang/rust/pull/68728/
+[68738]: https://github.com/rust-lang/rust/pull/68738/
+[68742]: https://github.com/rust-lang/rust/pull/68742/
+[68764]: https://github.com/rust-lang/rust/pull/68764/
+[68772]: https://github.com/rust-lang/rust/pull/68772/
+[68943]: https://github.com/rust-lang/rust/pull/68943/
+[68952]: https://github.com/rust-lang/rust/pull/68952/
+[68966]: https://github.com/rust-lang/rust/pull/68966/
+[68984]: https://github.com/rust-lang/rust/pull/68984/
+[69022]: https://github.com/rust-lang/rust/pull/69022/
+[69185]: https://github.com/rust-lang/rust/pull/69185/
+[69194]: https://github.com/rust-lang/rust/pull/69194/
+[69201]: https://github.com/rust-lang/rust/pull/69201/
+[69227]: https://github.com/rust-lang/rust/pull/69227/
+[69548]: https://github.com/rust-lang/rust/pull/69548/
+[69256]: https://github.com/rust-lang/rust/pull/69256/
+[69361]: https://github.com/rust-lang/rust/pull/69361/
+[69366]: https://github.com/rust-lang/rust/pull/69366/
+[69538]: https://github.com/rust-lang/rust/pull/69538/
+[cargo/7823]: https://github.com/rust-lang/cargo/pull/7823
+[cargo/7697]: https://github.com/rust-lang/cargo/pull/7697
+[`Once::is_completed`]: https://doc.rust-lang.org/std/sync/struct.Once.html#method.is_completed
+[`f32::LOG10_2`]: https://doc.rust-lang.org/std/f32/consts/constant.LOG10_2.html
+[`f32::LOG2_10`]: https://doc.rust-lang.org/std/f32/consts/constant.LOG2_10.html
+[`f64::LOG10_2`]: https://doc.rust-lang.org/std/f64/consts/constant.LOG10_2.html
+[`f64::LOG2_10`]: https://doc.rust-lang.org/std/f64/consts/constant.LOG2_10.html
+[`iter::once_with`]: https://doc.rust-lang.org/std/iter/fn.once_with.html
+
+
+Version 1.42.0 (2020-03-12)
+==========================
+
+Language
+--------
+- [You can now use the slice pattern syntax with subslices.][67712] e.g.
+ ```rust
+ fn foo(words: &[&str]) {
+ match words {
+ ["Hello", "World", "!", ..] => println!("Hello World!"),
+ ["Foo", "Bar", ..] => println!("Baz"),
+ rest => println!("{:?}", rest),
+ }
+ }
+ ```
+- [You can now use `#[repr(transparent)]` on univariant `enum`s.][68122] Meaning
+ that you can create an enum that has the exact layout and ABI of the type
+ it contains.
+- [There are some *syntax-only* changes:][67131]
+ - `default` is syntactically allowed before items in `trait` definitions.
+ - Items in `impl`s (i.e. `const`s, `type`s, and `fn`s) may syntactically
+ leave out their bodies in favor of `;`.
+ - Bounds on associated types in `impl`s are now syntactically allowed
+ (e.g. `type Foo: Ord;`).
+ - `...` (the C-variadic type) may occur syntactically directly as the type of
+ any function parameter.
+
+ These are still rejected *semantically*, so you will likely receive an error
+ but these changes can be seen and parsed by procedural macros and
+ conditional compilation.
+
+Compiler
+--------
+- [Added tier 2\* support for `armv7a-none-eabi`.][68253]
+- [Added tier 2 support for `riscv64gc-unknown-linux-gnu`.][68339]
+- [`Option::{expect,unwrap}` and
+ `Result::{expect, expect_err, unwrap, unwrap_err}` now produce panic messages
+ pointing to the location where they were called, rather than
+ `core`'s internals. ][67887]
+
+\* Refer to Rust's [platform support page][forge-platform-support] for more
+information on Rust's tiered platform support.
+
+Libraries
+---------
+- [`iter::Empty<T>` now implements `Send` and `Sync` for any `T`.][68348]
+- [`Pin::{map_unchecked, map_unchecked_mut}` no longer require the return type
+ to implement `Sized`.][67935]
+- [`io::Cursor` now derives `PartialEq` and `Eq`.][67233]
+- [`Layout::new` is now `const`.][66254]
+- [Added Standard Library support for `riscv64gc-unknown-linux-gnu`.][66899]
+
+
+Stabilized APIs
+---------------
+- [`CondVar::wait_while`]
+- [`CondVar::wait_timeout_while`]
+- [`DebugMap::key`]
+- [`DebugMap::value`]
+- [`ManuallyDrop::take`]
+- [`matches!`]
+- [`ptr::slice_from_raw_parts_mut`]
+- [`ptr::slice_from_raw_parts`]
+
+Cargo
+-----
+- [You no longer need to include `extern crate proc_macro;` to be able to
+ `use proc_macro;` in the `2018` edition.][cargo/7700]
+
+Compatibility Notes
+-------------------
+- [`Error::description` has been deprecated, and its use will now produce a
+ warning.][66919] It's recommended to use `Display`/`to_string` instead.
+
+[68253]: https://github.com/rust-lang/rust/pull/68253/
+[68348]: https://github.com/rust-lang/rust/pull/68348/
+[67935]: https://github.com/rust-lang/rust/pull/67935/
+[68339]: https://github.com/rust-lang/rust/pull/68339/
+[68122]: https://github.com/rust-lang/rust/pull/68122/
+[67712]: https://github.com/rust-lang/rust/pull/67712/
+[67887]: https://github.com/rust-lang/rust/pull/67887/
+[67131]: https://github.com/rust-lang/rust/pull/67131/
+[67233]: https://github.com/rust-lang/rust/pull/67233/
+[66899]: https://github.com/rust-lang/rust/pull/66899/
+[66919]: https://github.com/rust-lang/rust/pull/66919/
+[66254]: https://github.com/rust-lang/rust/pull/66254/
+[cargo/7700]: https://github.com/rust-lang/cargo/pull/7700
+[`DebugMap::key`]: https://doc.rust-lang.org/stable/std/fmt/struct.DebugMap.html#method.key
+[`DebugMap::value`]: https://doc.rust-lang.org/stable/std/fmt/struct.DebugMap.html#method.value
+[`ManuallyDrop::take`]: https://doc.rust-lang.org/stable/std/mem/struct.ManuallyDrop.html#method.take
+[`matches!`]: https://doc.rust-lang.org/stable/std/macro.matches.html
+[`ptr::slice_from_raw_parts_mut`]: https://doc.rust-lang.org/stable/std/ptr/fn.slice_from_raw_parts_mut.html
+[`ptr::slice_from_raw_parts`]: https://doc.rust-lang.org/stable/std/ptr/fn.slice_from_raw_parts.html
+[`CondVar::wait_while`]: https://doc.rust-lang.org/stable/std/sync/struct.Condvar.html#method.wait_while
+[`CondVar::wait_timeout_while`]: https://doc.rust-lang.org/stable/std/sync/struct.Condvar.html#method.wait_timeout_while
+
+
Version 1.41.1 (2020-02-27)
===========================
[69225]: https://github.com/rust-lang/rust/issues/69225
[69145]: https://github.com/rust-lang/rust/pull/69145
+
Version 1.41.0 (2020-01-30)
===========================
Language
--------
-* [`cfg_attr` works on `path` attributes](https://github.com/rust-lang/rust/pull/34546)
* [Support nested `cfg_attr` attributes](https://github.com/rust-lang/rust/pull/34216)
* [Allow statement-generating braced macro invocations at the end of blocks](https://github.com/rust-lang/rust/pull/34436)
* [Macros can be expanded inside of trait definitions](https://github.com/rust-lang/rust/pull/34213)
Language
--------
-* [Allow `concat_idents!` in type positions as well as in expression
- positions](https://github.com/rust-lang/rust/pull/33735).
* [`Copy` types are required to have a trivial implementation of `Clone`](https://github.com/rust-lang/rust/pull/33420).
[RFC 1521](https://github.com/rust-lang/rfcs/blob/master/text/1521-copy-clone-semantics.md).
* [Single-variant enums support the `#[repr(..)]` attribute](https://github.com/rust-lang/rust/pull/33355).
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