Announcing Rust 1.2

Today marks the completion of the Rust 1.2 stable and 1.3 beta release cycles! Read on for the highlight, or check the release notes for more detail.

What's in 1.2 stable

As we previously announced, Rust 1.2 comes with two major performance improvements for the compiler:

An across-the-board improvement to real-world compiler performance. Representative crates include hyper (compiles 1.16x faster), html5ever (1.62x faster), regex (1.32x faster) and rust-encoding (1.35x faster). You can explore some of this performance data at Nick Cameron's preliminary tracking site, using dates 2015-05-15 to 2015-06-25.
Parallel codegen is now working, and produces a 33% speedup when bootstrapping on a 4 core machine. Parallel codegen is particularly useful for debug builds, since it prevents some optimizations; but it can also be used with optimizations as an effective -O1 flag. It can be activated by passing -C codegen-units=N to rustc, where N is the desired number of threads.

Cargo's performance has also improved dramatically:

Builds that do not require any recompilation ("no-op builds") for large projects are much faster: for Servo, build time went from 5 seconds to 0.5 seconds.
Cargo now supports shared target directories that cache dependencies across multiple packages, which results in significant build-time reduction for complex projects.

The 1.2 release also introduces support for the MSVC (Microsoft Visual C) toolchain, as opposed to GNU variants. The upshot is that Rust code is now directly linkable against code built using the native Windows toolchain. The compiler bootstraps on MSVC, we have preliminary nightlies, and we are testing all rust-lang crates against MSVC. Unwinding support is not yet available (the process aborts on panic), but work is underway to land it.

On the language side, Rust 1.2 marks the completion of the dynamically-sized type (DST) work, allowing smart pointers like Rc to seamless apply to arrays and trait objects, so that Rc<[T]> is fully usable. This final enhancement applies to all smart pointers in the standard library. Support for external smart pointer types is available in nightlies, and will be stabilized soon.

What's in 1.3 beta

One of the most exciting developments during the 1.3 cycle was the introduction of the Rustonomicon, a new book covering "The Dark Arts of Advanced and Unsafe Rust Programming". While it's still in its early days, this book already provides indispensable coverage of some of Rust's more subtle aspects.

The 1.3 cycle also saw additional focus on performance, though most wins here are within the standard library:

The substring matcher now uses a more efficient algorithm.
There were improvements to zero filling that speed up Vec::resize and Read::read_to_end.
The implementation of Read::read_to_end has been specialized for stdin and File, resulting in additional speedups.
The PartialEq implementation on slices is now much faster.

We have also made strides in our Windows support, landing preliminary support for targeting Windows XP. While we do not intend to treat Windows XP as a "first tier" platform, it is now feasible to build Rust code for XP as long as you avoid certain parts of the standard library.

On the Cargo front, we have landed support for lint capping as specified by an earlier RFC. The idea is that lints in your dependencies should not affect your ability to compile cleanly, which in turn makes it easier to tweak the way lints work without undue hassle in the ecosystem.

Contributors to 1.2

The 1.2 stable release represents the hard work of 180 fine folks:

Aaron Turon
Abhishek Chanda
Adolfo Ochagavía
Aidan Hobson Sayers
Akshay Chiwhane
Alex Burka
Alex Crichton
Alex Stokes
Alexander Artemenko
Alexis Beingessner
Andrea Canciani
Andrew Foote
Andrew Kensler
Andrew Straw
Ariel Ben-Yehuda
Austin Hellyer
Barosl Lee
Ben Striegel
Björn Steinbrink
Brian Anderson
Brian Campbell
Brian Leibig
Brian Quinlan
Carol (Nichols || Goulding)
Chris Hellmuth
Christian Stadelmann
Chuck Bassett
Corey Farwell
Cornel Punga
Cruz Julian Bishop
Dave Huseby
David Campbell
David Stygstra
David Voit
Eduard Bopp
Eduard Burtescu
Eli Friedman
Emilio Cobos Álvarez
Emily Dunham
Eric Ye
Erik Michaels-Ober
Falco Hirschenberger
Felix S. Klock II
FuGangqiang
Geoffrey Thomas
Gleb Kozyrev
Guillaume Gomez
Gulshan Singh
Heejong Ahn
Huachao Huang
Huon Wilson
Ivan Ukhov
Iven Hsu
Jake Goulding
Jake Hickey
James Miller
Jared Roesch
Jeremy Schlatter
Jexell
Jim Blandy
Johann Tuffe
Johannes Hoff
Johannes Oertel
John Hodge
Jonathan Reem
Joshua Landau
Kevin Ballard
Kubilay Kocak
Lee Jeffery
Leo Correa
Liigo Zhuang
Lorenz
Luca Bruno
Luqman Aden
Manish Goregaokar
Marcel Müller
Marcus Klaas
Marin Atanasov Nikolov
Markus Westerlind
Martin Pool
Marvin Löbel
Matej Lach
Mathieu David
Matt Brubeck
Matthew Astley
Max Jacobson
Maximilian Haack
Michael Layzell
Michael Macias
Michael Rosenberg
Michael Sproul
Michael Woerister
Mihnea Dobrescu-Balaur
Mikhail Zabaluev
Mohammed Attia
Ms2ger
Murarth
Mário Feroldi
Nathan Long
Nathaniel Theis
Nick Cameron
Nick Desaulniers
Nick Fitzgerald
Nick Hamann
Nick Howell
Niko Matsakis
Nils Liberg
OlegTsyba
Oliver 'ker' Schneider
Oliver Schneider
P1start
Parker Moore
Pascal Hertleif
Paul Faria
Paul Oliver
Peer Aramillo Irizar
Peter Atashian
Peter Elmers
Philip Munksgaard
Ralph Giles
Rein Henrichs
Ricardo Martins
Richo Healey
Ricky Taylor
Russell Johnston
Russell McClellan
Ryan Pendleton
Ryman
Rémi Audebert
Sae-bom Kim
Sean Collins
Sean Gillespie
Sean Patrick Santos
Seo Sanghyeon
Simon Sapin
Simonas Kazlauskas
Steve Gury
Steve Klabnik
Steven Allen
Steven Fackler
Steven Walter
Sébastien Marie
Tamir Duberstein
Thomas Karpiniec
Tim Ringenbach
Tshepang Lekhonkhobe
Ulrik Sverdrup
Vadim Petrochenkov
Wei-Ming Yang
Wesley Wiser
Wilfred Hughes
Will Andrews
Will Engler
Xuefeng Wu
XuefengWu
Yongqian Li
York Xiang
Z1
ben fleis
benaryorg
bluss
bors
clatour
diwic
dmgawel
econoplas
frankamp
funkill
inrustwetrust
joliv
klutzy
marcell
mdinger
olombard
peferron
ray glover
saml
simplex
sumito3478
webmobster