Rust 1.47.0

Language

--------

- [Closures will now warn when not used.][74869]

Compiler

--------

- [Stabilized the -C control-flow-guard codegen option][73893], which enables

[Control Flow Guard][1.47.0-cfg] for Windows platforms, and is ignored on other

platforms.

- [Upgraded to LLVM 11.][73526]

- [Added tier 3\* support for the thumbv4t-none-eabi target.][74419]

- [Upgrade the FreeBSD toolchain to version 11.4][75204]

- [RUST_BACKTRACE's output is now more compact.][75048]

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

information on Rust's tiered platform support.

Libraries

---------

- [CStr now implements Index>.][74021]

- [Traits in std/core are now implemented for arrays of any length, not just

those of length less than 33.][74060]

- [ops::RangeFull and ops::Range now implement Default.][73197]

- [panic::Location now implements Copy, Clone, Eq, Hash, Ord,

PartialEq, and PartialOrd.][73583]

Stabilized APIs

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

- [Ident::new_raw]

- [Range::is_empty]

- [RangeInclusive::is_empty]

- [Result::as_deref]

- [Result::as_deref_mut]

- [Vec::leak]

- [pointer::offset_from]

- [f32::TAU]

- [f64::TAU]

The following previously stable APIs have now been made const.

- [The new method for all NonZero integers.][73858]

- [The checked_add,checked_sub,checked_mul,checked_neg, checked_shl,

checked_shr, saturating_add, saturating_sub, and saturating_mul

methods for all integers.][73858]

- [The checked_abs, saturating_abs, saturating_neg, and signum for all

signed integers.][73858]

- [The is_ascii_alphabetic, is_ascii_uppercase, is_ascii_lowercase,

is_ascii_alphanumeric, is_ascii_digit, is_ascii_hexdigit, is_ascii_punctuation, is_ascii_graphic, is_ascii_whitespace, and is_ascii_control methods for char and u8.][73858]

Cargo

-----

- [build-dependencies are now built with opt-level 0 by default.][cargo/8500]

You can override this by setting the following in your Cargo.toml.

  [profile.release.build-override]
opt-level = 3

- [cargo-help will now display man pages for commands rather just the

--help text.][cargo/8456]

- [cargo-metadata now emits a test field indicating if a target has

tests enabled.][cargo/8478]

- [workspace.default-members now respects workspace.exclude.][cargo/8485]

- [cargo-publish will now use an alternative registry by default if it's the

only registry specified in package.publish.][cargo/8571]

Misc

----

- [Added a help button beside Rustdoc's searchbar that explains rustdoc's

type based search.][75366]

- [Added the Ayu theme to rustdoc.][71237]

Compatibility Notes

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

- [Bumped the minimum supported Emscripten version to 1.39.20.][75716]

- [Fixed a regression parsing {} && false in tail expressions.][74650]

- [Added changes to how proc-macros are expanded in macro_rules! that should

help to preserve more span information.][73084] These changes may cause

compilation errors if your macro was unhygenic or didn't correctly handle

Delimiter::None.

- [Moved support for the CloudABI target to tier 3.][75568]

- [linux-gnu targets now require minimum kernel 2.6.32 and glibc 2.11.][74163]

- [Added the rustc-docs component.][75560] This allows you to install

and read the documentation for the compiler internal APIs. (Currently only

available for x86_64-unknown-linux-gnu.)

Internal Only

--------

- [Improved default settings for bootstrapping in x.py.][73964] You can read details about this change in the "Changes to x.py defaults" post on the Inside Rust blog.

[1.47.0-cfg]: https://docs.microsoft.com/en-us/windows/win32/secbp/control-flow-guard

[75048]: https://github.com/rust-lang/rust/pull/75048/

[74163]: https://github.com/rust-lang/rust/pull/74163/

[71237]: https://github.com/rust-lang/rust/pull/71237/

[74869]: https://github.com/rust-lang/rust/pull/74869/

[73858]: https://github.com/rust-lang/rust/pull/73858/

[75716]: https://github.com/rust-lang/rust/pull/75716/

[75560]: https://github.com/rust-lang/rust/pull/75560/

[75568]: https://github.com/rust-lang/rust/pull/75568/

[75366]: https://github.com/rust-lang/rust/pull/75366/

[75204]: https://github.com/rust-lang/rust/pull/75204/

[74650]: https://github.com/rust-lang/rust/pull/74650/

[74419]: https://github.com/rust-lang/rust/pull/74419/

[73964]: https://github.com/rust-lang/rust/pull/73964/

[74021]: https://github.com/rust-lang/rust/pull/74021/

[74060]: https://github.com/rust-lang/rust/pull/74060/

[73893]: https://github.com/rust-lang/rust/pull/73893/

[73526]: https://github.com/rust-lang/rust/pull/73526/

[73583]: https://github.com/rust-lang/rust/pull/73583/

[73084]: https://github.com/rust-lang/rust/pull/73084/

[73197]: https://github.com/rust-lang/rust/pull/73197/

[cargo/8456]: https://github.com/rust-lang/cargo/pull/8456/

[cargo/8478]: https://github.com/rust-lang/cargo/pull/8478/

[cargo/8485]: https://github.com/rust-lang/cargo/pull/8485/

[cargo/8500]: https://github.com/rust-lang/cargo/pull/8500/

[cargo/8571]: https://github.com/rust-lang/cargo/pull/8571/

[Ident::new_raw]: https://doc.rust-lang.org/nightly/proc_macro/struct.Ident.html#method.new_raw

[Range::is_empty]: https://doc.rust-lang.org/nightly/std/ops/struct.Range.html#method.is_empty

[RangeInclusive::is_empty]: https://doc.rust-lang.org/nightly/std/ops/struct.RangeInclusive.html#method.is_empty

[Result::as_deref_mut]: https://doc.rust-lang.org/nightly/std/result/enum.Result.html#method.as_deref_mut

[Result::as_deref]: https://doc.rust-lang.org/nightly/std/result/enum.Result.html#method.as_deref

[Vec::leak]: https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.leak

[f32::TAU]: https://doc.rust-lang.org/nightly/std/f32/consts/constant.TAU.html

[f64::TAU]: https://doc.rust-lang.org/nightly/std/f64/consts/constant.TAU.html

[pointer::offset_from]: https://doc.rust-lang.org/nightly/std/primitive.pointer.html#method.offset_from