Rust 1.30.0

Language

--------

- [Procedural macros are now available.][52081] These kinds of macros allow for

more powerful code generation. There is a [new chapter available][proc-macros]

in the Rust Programming Language book that goes further in depth.

- [You can now use keywords as identifiers using the raw identifiers

syntax (r#),][53236] e.g. let r#for = true;

- [Using anonymous parameters in traits is now deprecated with a warning and

will be a hard error in the 2018 edition.][53272]

- [You can now use crate in paths.][54404] This allows you to refer to the

crate root in the path, e.g. use crate::foo; refers to foo in src/lib.rs.

- [Using a external crate no longer requires being prefixed with ::.][54404]

Previously, using a external crate in a module without a use statement

required let json = ::serde_json::from_str(foo); but can now be written

as let json = serde_json::from_str(foo);.

- [You can now apply the #[used] attribute to static items to prevent the

compiler from optimising them away, even if they appear to be unused,][51363]

e.g. #[used] static FOO: u32 = 1;

- [You can now import and reexport macros from other crates with the use

syntax.][50911] Macros exported with #[macro_export] are now placed into

the root module of the crate. If your macro relies on calling other local

macros, it is recommended to export with the

#[macro_export(local_inner_macros)] attribute so users won't have to import

those macros.

- [You can now catch visibility keywords (e.g. pub, pub(crate)) in macros

using the vis specifier.][53370]

- [Non-macro attributes now allow all forms of literals, not just

strings.][53044] Previously, you would write #[attr("true")], and you can now

write #[attr(true)].

- [You can now specify a function to handle a panic in the Rust runtime with the

#[panic_handler] attribute.][51366]

Compiler

--------

- [Added the riscv32imc-unknown-none-elf target.][53822]

- [Added the aarch64-unknown-netbsd target][53165]

- [Upgraded to LLVM 8.][53611]

Libraries

---------

- [ManuallyDrop now allows the inner type to be unsized.][53033]

Stabilized APIs

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

- [Ipv4Addr::BROADCAST]

- [Ipv4Addr::LOCALHOST]

- [Ipv4Addr::UNSPECIFIED]

- [Ipv6Addr::LOCALHOST]

- [Ipv6Addr::UNSPECIFIED]

- [Iterator::find_map]

The following methods are replacement methods for trim_left, trim_right,

trim_left_matches, and trim_right_matches, which will be deprecated

in 1.33.0:

- [str::trim_end_matches]

- [str::trim_end]

- [str::trim_start_matches]

- [str::trim_start]

Cargo

----

- [cargo run doesn't require specifying a package in workspaces.][cargo/5877]

- [cargo doc now supports --message-format=json.][cargo/5878] This is

equivalent to calling rustdoc --error-format=json.

- [Cargo will now provide a progress bar for builds.][cargo/5995]

Misc

----

- [rustdoc allows you to specify what edition to treat your code as with the

--edition option.][54057]

- [rustdoc now has the --color (specify whether to output color) and

--error-format (specify error format, e.g. json) options.][53003]

- [We now distribute a rust-gdbgui script that invokes gdbgui with Rust

debug symbols.][53774]

- [Attributes from Rust tools such as rustfmt or clippy are now

available,][53459] e.g. #[rustfmt::skip] will skip formatting the next item.

[50911]: https://github.com/rust-lang/rust/pull/50911/

[51363]: https://github.com/rust-lang/rust/pull/51363/

[51366]: https://github.com/rust-lang/rust/pull/51366/

[52081]: https://github.com/rust-lang/rust/pull/52081/

[53003]: https://github.com/rust-lang/rust/pull/53003/

[53033]: https://github.com/rust-lang/rust/pull/53033/

[53044]: https://github.com/rust-lang/rust/pull/53044/

[53165]: https://github.com/rust-lang/rust/pull/53165/

[53611]: https://github.com/rust-lang/rust/pull/53611/

[53236]: https://github.com/rust-lang/rust/pull/53236/

[53272]: https://github.com/rust-lang/rust/pull/53272/

[53370]: https://github.com/rust-lang/rust/pull/53370/

[53459]: https://github.com/rust-lang/rust/pull/53459/

[53774]: https://github.com/rust-lang/rust/pull/53774/

[53822]: https://github.com/rust-lang/rust/pull/53822/

[54057]: https://github.com/rust-lang/rust/pull/54057/

[54404]: https://github.com/rust-lang/rust/pull/54404/

[cargo/5877]: https://github.com/rust-lang/cargo/pull/5877/

[cargo/5878]: https://github.com/rust-lang/cargo/pull/5878/

[cargo/5995]: https://github.com/rust-lang/cargo/pull/5995/

[proc-macros]: https://doc.rust-lang.org/nightly/book/2018-edition/ch19-06-macros.html

[Ipv4Addr::BROADCAST]: https://doc.rust-lang.org/nightly/std/net/struct.Ipv4Addr.html#associatedconstant.BROADCAST

[Ipv4Addr::LOCALHOST]: https://doc.rust-lang.org/nightly/std/net/struct.Ipv4Addr.html#associatedconstant.LOCALHOST

[Ipv4Addr::UNSPECIFIED]: https://doc.rust-lang.org/nightly/std/net/struct.Ipv4Addr.html#associatedconstant.UNSPECIFIED

[Ipv6Addr::LOCALHOST]: https://doc.rust-lang.org/nightly/std/net/struct.Ipv6Addr.html#associatedconstant.LOCALHOST

[Ipv6Addr::UNSPECIFIED]: https://doc.rust-lang.org/nightly/std/net/struct.Ipv6Addr.html#associatedconstant.UNSPECIFIED

[Iterator::find_map]: https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.find_map

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

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

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

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