Rust 1.46.0

Language

--------

- [if, match, and loop expressions can now be used in const functions.][72437]

- [Additionally you are now also able to coerce and cast to slices (&[T]) in

const functions.][73862]

- [The #[track_caller] attribute can now be added to functions to use the

function's caller's location information for panic messages.][72445]

- [Recursively indexing into tuples no longer needs parentheses.][71322] E.g.

x.0.0 over (x.0).0.

- [mem::transmute can now be used in statics and constants.][72920] Note

You currently can't use mem::transmute in constant functions.

Compiler

--------

- [You can now use the cdylib target on Apple iOS and tvOS platforms.][73516]

- [Enabled static "Position Independent Executables" by default

for x86_64-unknown-linux-musl.][70740]

Libraries

---------

- [mem::forget is now a const fn.][73887]

- [String now implements From.][73466]

- [The leading_ones, and trailing_ones methods have been stabilised for all

integer types.][73032]

- [vec::IntoIter now implements AsRef<[T]>.][72583]

- [All non-zero integer types (NonZeroU8) now implement TryFrom for their

zero-able equivalent (e.g. TryFrom).][72717]

- [&[T] and &mut [T] now implement PartialEq>.][71660]

- [(String, u16) now implements ToSocketAddrs.][73007]

- [vec::Drain<'_, T> now implements AsRef<[T]>.][72584]

Stabilized APIs

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

- [Option::zip]

- [vec::Drain::as_slice]

Cargo

-----

Added a number of new environment variables that are now available when

compiling your crate.

- [CARGO_BIN_NAME and CARGO_CRATE_NAME][cargo/8270] Providing the name of

the specific binary being compiled and the name of the crate.

- [CARGO_PKG_LICENSE][cargo/8325] The license from the manifest of the package.

- [CARGO_PKG_LICENSE_FILE][cargo/8387] The path to the license file.

Compatibility Notes

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

- [The target configuration option abi_blacklist has been renamed

to unsupported_abis.][74150] The old name will still continue to work.

- [Rustc will now warn if you cast a C-like enum that implements Drop.][72331]

This was previously accepted but will become a hard error in a future release.

- [Rustc will fail to compile if you have a struct with

#[repr(i128)] or #[repr(u128)].][74109] This representation is currently only

allowed on enums.

- [Tokens passed to macro_rules! are now always captured.][73293] This helps

ensure that spans have the correct information, and may cause breakage if you

were relying on receiving spans with dummy information.

- [The InnoSetup installer for Windows is no longer available.][72569] This was

a legacy installer that was replaced by a MSI installer a few years ago but

was still being built.

- [{f32, f64}::asinh now returns the correct values for negative numbers.][72486]

- [Rustc will no longer accept overlapping trait implementations that only

differ in how the lifetime was bound.][72493]

- [Rustc now correctly relates the lifetime of an existential associated

type.][71896] This fixes some edge cases where rustc would erroneously allow

you to pass a shorter lifetime than expected.

- [Rustc now dynamically links to libz (also called zlib) on Linux.][74420]

The library will need to be installed for rustc to work, even though we

expect it to be already available on most systems.

- [Tests annotated with #[should_panic] are broken on ARMv7 while running

under QEMU.][74820]

- [Pretty printing of some tokens in procedural macros changed.][75453] The

exact output returned by rustc's pretty printing is an unstable

implementation detail: we recommend any macro relying on it to switch to a

more robust parsing system.

[75453]: https://github.com/rust-lang/rust/issues/75453/

[74820]: https://github.com/rust-lang/rust/issues/74820/

[74420]: https://github.com/rust-lang/rust/issues/74420/

[74109]: https://github.com/rust-lang/rust/pull/74109/

[74150]: https://github.com/rust-lang/rust/pull/74150/

[73862]: https://github.com/rust-lang/rust/pull/73862/

[73887]: https://github.com/rust-lang/rust/pull/73887/

[73466]: https://github.com/rust-lang/rust/pull/73466/

[73516]: https://github.com/rust-lang/rust/pull/73516/

[73293]: https://github.com/rust-lang/rust/pull/73293/

[73007]: https://github.com/rust-lang/rust/pull/73007/

[73032]: https://github.com/rust-lang/rust/pull/73032/

[72920]: https://github.com/rust-lang/rust/pull/72920/

[72569]: https://github.com/rust-lang/rust/pull/72569/

[72583]: https://github.com/rust-lang/rust/pull/72583/

[72584]: https://github.com/rust-lang/rust/pull/72584/

[72717]: https://github.com/rust-lang/rust/pull/72717/

[72437]: https://github.com/rust-lang/rust/pull/72437/

[72445]: https://github.com/rust-lang/rust/pull/72445/

[72486]: https://github.com/rust-lang/rust/pull/72486/

[72493]: https://github.com/rust-lang/rust/pull/72493/

[72331]: https://github.com/rust-lang/rust/pull/72331/

[71896]: https://github.com/rust-lang/rust/pull/71896/

[71660]: https://github.com/rust-lang/rust/pull/71660/

[71322]: https://github.com/rust-lang/rust/pull/71322/

[70740]: https://github.com/rust-lang/rust/pull/70740/

[cargo/8270]: https://github.com/rust-lang/cargo/pull/8270/

[cargo/8325]: https://github.com/rust-lang/cargo/pull/8325/

[cargo/8387]: https://github.com/rust-lang/cargo/pull/8387/

[Option::zip]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.zip

[vec::Drain::as_slice]: https://doc.rust-lang.org/stable/std/vec/struct.Drain.html#method.as_slice