Version 1.55.0 (2021-09-09)

============================

Language

--------

- [You can now write open "from" range patterns (`X..`), which will start at `X` and

will end at the maximum value of the integer.][83918]

- [You can now explicitly import the prelude of different editions

through `std::prelude` (e.g. `use std::prelude::rust_2021::*;`).][86294]

Compiler

--------

- [Added tier 3\* support for `powerpc64le-unknown-freebsd`.][83572]

\* Refer to Rust's [platform support page][platform-support-doc] for more

information on Rust's tiered platform support.

Libraries

---------

- [Updated std's float parsing to use the Eisel-Lemire algorithm.][86761]

These improvements should in general provide faster string parsing of floats,

no longer reject certain valid floating point values, and reduce

the produced code size for non-stripped artifacts.

- [`string::Drain` now implements `AsRef<str>` and `AsRef<[u8]>`.][86858]

Stabilised APIs

---------------

- [`Bound::cloned`]

- [`Drain::as_str`]

- [`IntoInnerError::into_error`]

- [`IntoInnerError::into_parts`]

- [`MaybeUninit::assume_init_mut`]

- [`MaybeUninit::assume_init_ref`]

- [`MaybeUninit::write`]

- [`array::map`]

- [`ops::ControlFlow`]

- [`x86::_bittest`]

- [`x86::_bittestandcomplement`]

- [`x86::_bittestandreset`]

- [`x86::_bittestandset`]

- [`x86_64::_bittest64`]

- [`x86_64::_bittestandcomplement64`]

- [`x86_64::_bittestandreset64`]

- [`x86_64::_bittestandset64`]

The following previously stable functions are now `const`.

- [`str::from_utf8_unchecked`]

- [`mem::transmute`]

Cargo

-----

- [Cargo will now deduplicate compiler diagnostics to the terminal when invoking

rustc in parallel such as when using `cargo test`.][cargo/9675]

- [The package definition in `cargo metadata` now includes the `"default_run"`

field from the manifest.][cargo/9550]

- [Added `cargo d` as an alias for `cargo doc`.][cargo/9680]

- [Added `{lib}` as formatting option for `cargo tree` to print the `"lib_name"`

of packages.][cargo/9663]

Rustdoc

-------

- [Added "Go to item on exact match" search option.][85876]

- [The "Implementors" section on traits no longer shows redundant

method definitions.][85970]

- [Trait implementations are toggled open by default.][86260] This should make the

implementations more searchable by tools like `CTRL+F` in your browser.

- [Intra-doc links should now correctly resolve associated items (e.g. methods)

through type aliases.][86334]

- [Traits which are marked with `#[doc(hidden)]` will no longer appear in the

"Trait Implementations" section.][86513]

Compatibility Notes

-------------------

- [std functions that return an `io::Error` will no longer use the

`ErrorKind::Other` variant.][85746] This is to better reflect that these

kinds of errors could be categorised [into newer more specific `ErrorKind`

variants][79965], and that they do not represent a user error.

- [Using environment variable names with `process::Command` on Windows now

behaves as expected.][85270] Previously using envionment variables with

`Command` would cause them to be ASCII-uppercased.

- [Rustdoc will now warn on using rustdoc lints that aren't prefixed

with `rustdoc::`][86849]

[86849]: https://github.com/rust-lang/rust/pull/86849

[86513]: https://github.com/rust-lang/rust/pull/86513

[86334]: https://github.com/rust-lang/rust/pull/86334

[86260]: https://github.com/rust-lang/rust/pull/86260

[85970]: https://github.com/rust-lang/rust/pull/85970

[85876]: https://github.com/rust-lang/rust/pull/85876

[83572]: https://github.com/rust-lang/rust/pull/83572

[86294]: https://github.com/rust-lang/rust/pull/86294

[86858]: https://github.com/rust-lang/rust/pull/86858

[86761]: https://github.com/rust-lang/rust/pull/86761

[85769]: https://github.com/rust-lang/rust/pull/85769

[85746]: https://github.com/rust-lang/rust/pull/85746

[85305]: https://github.com/rust-lang/rust/pull/85305

[85270]: https://github.com/rust-lang/rust/pull/85270

[84111]: https://github.com/rust-lang/rust/pull/84111

[83918]: https://github.com/rust-lang/rust/pull/83918

[79965]: https://github.com/rust-lang/rust/pull/79965

[87370]: https://github.com/rust-lang/rust/pull/87370

[87298]: https://github.com/rust-lang/rust/pull/87298

[cargo/9663]: https://github.com/rust-lang/cargo/pull/9663

[cargo/9675]: https://github.com/rust-lang/cargo/pull/9675

[cargo/9550]: https://github.com/rust-lang/cargo/pull/9550

[cargo/9680]: https://github.com/rust-lang/cargo/pull/9680

[cargo/9663]: https://github.com/rust-lang/cargo/pull/9663

[`array::map`]: https://doc.rust-lang.org/stable/std/primitive.array.html#method.map

[`Bound::cloned`]: https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.cloned

[`Drain::as_str`]: https://doc.rust-lang.org/stable/std/string/struct.Drain.html#method.as_str

[`IntoInnerError::into_error`]: https://doc.rust-lang.org/stable/std/io/struct.IntoInnerError.html#method.into_error

[`IntoInnerError::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.IntoInnerError.html#method.into_parts

[`MaybeUninit::assume_init_mut`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_mut

[`MaybeUninit::assume_init_ref`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_ref

[`MaybeUninit::write`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.write

[`Seek::rewind`]: https://doc.rust-lang.org/stable/std/io/trait.Seek.html#method.rewind

[`mem::transmute`]: https://doc.rust-lang.org/stable/std/mem/fn.transmute.html

[`ops::ControlFlow`]: https://doc.rust-lang.org/stable/std/ops/enum.ControlFlow.html

[`str::from_utf8_unchecked`]: https://doc.rust-lang.org/stable/std/str/fn.from_utf8_unchecked.html

[`x86::_bittest`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittest.html

[`x86::_bittestandcomplement`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandcomplement.html

[`x86::_bittestandreset`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandreset.html

[`x86::_bittestandset`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandset.html

[`x86_64::_bittest64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittest64.html

[`x86_64::_bittestandcomplement64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandcomplement64.html

[`x86_64::_bittestandreset64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandreset64.html

[`x86_64::_bittestandset64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandset64.html

- [You can now use macros for values in some built-in attributes.][83366]

This primarily allows you to call macros within the `#[doc]` attribute. For

example, to include external documentation in your crate, you can now write

the following:

- [`-Zmutable-noalias=yes`][82834] is enabled by default when using LLVM 12 or above.

[82834]: https://github.com/rust-lang/rust/pull/82834

(`NaN`, `-0`) according to IEEE 754.][78618]