Announcing Rust 1.10

The Rust team is happy to announce the latest version of Rust, 1.10. Rust is a systems programming language focused on safety, speed, and concurrency.

As always, you can install Rust 1.10 from the appropriate page on our website, and check out the detailed release notes for 1.10 on GitHub. 1276 patches were landed in this release.

What's in 1.10 stable

Rust 1.10 contains one of the most-requested features in Rust: through the -C panic=abort flag or a setting in your Cargo.toml, when a panic! happens, it will abort rather than unwind. Why would you want to do this? Remember that panics are for unexpected problems, and for many applications, aborting is a reasonable choice. With an abort, less code gets generated, meaning that binary sizes are a bit smaller, and compilation time is ever-so-slightly faster. Some very rough numbers are 10% smaller binaries, and 10% faster compilation time. This feature was defined in RFC 1513.

The second big feature in 1.10 is a new crate type: cdylib. The existing dylib dynamic library format will now be used solely for writing a dynamic library to be used within a Rust project, while cdylibs will be used when compiling Rust code as a dynamic library to be embedded in another language. With the 1.10 release, cdylibs are supported by the compiler, but not yet in Cargo. This format was defined in RFC 1510.

In addition, a number of performance improvements landed in the compiler, and so did a number of usability improvements across the documentation, rustdoc itself, and various error messages.

Finally, there's a large change to the way that we develop Rust that won't impact Rust users directly, but will help those distributing Rust significantly. Rust is implemented in Rust, which means that to build a copy of Rust, you need a copy of Rust. This is commonly referred to as 'bootstrapping'. Historically, we would do this by "snapshotting" a specific version of the compiler, and always bootstrapping from that; the snapshot would periodically be updated, as needed. Furthermore, since the Rust compiler uses unstable Rust features, in order to build a copy of the stable compiler, you would need a specific nightly version of the Rust compiler. This has served us well for years, but we've outgrown it now. The main drawback to this approach is that it requires downloading a snapshot binary, which is not ideal for an important constituency: Linux distributions. In particular, distros generally want to be able to build the latest version of Rust using only previously-packaged versions that they have produced, rather than via untrusted binaries. As such, we have modified our build system so that Rust 1.10 builds with Rust 1.9. In the future, this pattern will continue; Rust 1.11 will be built with Rust 1.10. Furthermore, you can use the stable compiler to build the compiler. This simplifies everything around bootstrapping, and helps distribution maintainers significantly, as they no longer need two packages. You can find more details about this change in its pull request.

See the detailed release notes for more.

Library stabilizations

Roughly 70 APIs were made stable in this release. They break down into these rough groups:

std::os::windows::fs::OpenOptionsExt, for Windows-specific file operations.
The ability to register and unregister panic hooks with std::panic::{set,take}_hook.
CStr::from_bytes_with_nul, to create a CStr from a byte slice (and an unchecked variant).
Small improvements to std::fs::Metadata.
compare_exchange for various atomic types.
A lot of UNIX-specific networking capabilities via std::os::unix::net::{UnixStream, UnixListener, UnixDatagram, SocketAddr}.

In addition, Default was implemented for &CStr, CString, UnsafeCell, fmt::Error, Condvar, Mutex, and RwLock.

Finally, on Linux, if HashMaps can't be initialized with getrandom they will fall back to /dev/urandom temporarily to avoid blocking during early boot.

See the detailed release notes for more.

Cargo features

Cargo has received a number of small improvements in this release.

The aforementioned profile.*.panic option can control how you'd like panics implemented for your project.
Cargo now reports its status to stderr rather than stdout.
Rust keywords are now banned from crate names.
The --force flag has been added to cargo install.
cargo test now takes a --doc flag for running only documentation tests.
cargo --explain was added, mirroring rustc --explain.

See the detailed release notes for more.

Contributors to 1.10

We had 139 individuals contribute to 1.10. Thank you so much!

Adolfo Ochagavía
Alan Somers
Alec S
Alex Burka
Alex Crichton
Alex Ozdemir
Amanieu d'Antras
Andrea Canciani
Andrew Paseltiner
Andrey Tonkih
Andy Russell
Anton Blanchard
Ariel Ben-Yehuda
Barosl Lee
benaryorg
billyevans
Björn Steinbrink
bnewbold
bors
Brandon Edens
Brayden Winterton
Brian Anderson
Brian Campbell
Brian Green
c4rlo
Christopher Serr
Corey Farwell
Cristian Oliveira
Cyryl Płotnicki-Chudyk
Dan Fockler
Daniel Campoverde [alx741]
Dave Huseby
David Hewitt
David Tolnay
Deepak Kannan
Demetri Obenour
Doug Goldstein
Eduard Burtescu
Eduard-Mihai Burtescu
Ergenekon Yigit
Fabrice Desré
Felix S. Klock II
Florian Berger
Garrett Squire
Geordon Worley
Georg Brandl
ggomez
Gigih Aji Ibrahim
Guillaume Bonnet
Guillaume Gomez
Haiko Schol
Jake Goulding
James Miller
jbranchaud
Jeffrey Seyfried
jethrogb
jocki84
Johannes Oertel
Jonas Schievink
jonathandturner
Jonathan S
Jonathan Turner
JP Sugarbroad
Kaiyin Zhong
Kamal Marhubi
Kevin Butler
Léo Testard
Luca Bruno
Lukas Kalbertodt
Lukas Pustina
Luqman Aden
Manish Goregaokar
Marcus Klaas
mark-summerfield
Masood Malekghassemi
Matt Brubeck
Matt Kraai
Maxim Samburskiy
Michael Howell
Michael Tiller
Michael Woerister
mitaa
mrmiywj
Ms2ger
Murarth
Nerijus Arlauskas
Nick Cameron
Nick Fitzgerald
Nick Hamann
Nick Platt
Niko Matsakis
Oliver 'ker' Schneider
Oliver Middleton
Oliver Schneider
Patrick Walton
Pavel Sountsov
Philipp Matthias Schaefer
Philipp Oppermann
pierzchalski
Postmodern
pravic
Pyry Kontio
Raph Levien
Rémy Rakic
rkjnsn
Robert Habermeier
Robin Kruppe
Sander Maijers
Scott Olson
Sean Gillespie
Sébastien Marie
Seo Sanghyeon
silvo38
Simonas Kazlauskas
Simon Wollwage
Stefan Schindler
Stephen Mather
Steve Klabnik
Steven Burns
Steven Fackler
Szabolcs Berecz
Tamir Duberstein
Tang Chenglong
Taylor Cramer
Ticki
Timon Van Overveldt
Timothy McRoy
Tobias Bucher
Tobias Müller
Tomáš Hübelbauer
Tomoki Aonuma
Tshepang Lekhonkhobe
Ulrik Sverdrup
User
Vadim Chugunov
Vadim Petrochenkov
Val Vanderschaegen
Wang Xuerui
York Xiang