Rust 1.12 release announcement #126
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| title: "Announcing Rust 1.12.0" | ||
| author: The Rust Core Team | ||
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| The Rust team is happy to announce the latest version of Rust, 1.12.0. Rust is a | ||
| systems programming language focused on safety, speed, and concurrency. | ||
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| As always, you can [install Rust 1.12.0][install] from the appropriate page on our | ||
| website, and check out the [detailed release notes for 1.12.0][notes] on GitHub. | ||
| 1361 patches were landed in this release. | ||
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| [install]: https://www.rust-lang.org/install.html | ||
| [notes]: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1120-2016-09-29 | ||
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| ### What's in 1.12.0 stable | ||
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| Oh my god! So much stuff! | ||
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| With 1.12 stable, one of the first visible changes you will notice is the new | ||
| error message format emitted by `rustc`. We've [previously talked] about this | ||
| format and this is the first release where they are broadly available. These | ||
| error messages are a result of the effort of many hours of [volunteer effort] to | ||
| design, test, and update every one of `rustc`s errors to the new format. We're | ||
| excited to see what you think of them: | ||
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There was a problem hiding this comment. Do we want to use the same trait error in both this section and the expanded section below? Might read better to have pictures of a different kind of error here. |
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| The other major change in this release is moving to a new compiler backend based | ||
| on the new Rust [MIR]. While this feature does not result in any new | ||
| user-visible features, it paves the way for a number of future compiler | ||
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There was a problem hiding this comment. Repeating the word "feature" sounds weird, I would change the first occurrence to "change". |
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| optimizations, and for some codebases it already results in improvements to | ||
| compile times and reductions in code size. | ||
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| [previously talked]: https://blog.rust-lang.org/2016/08/10/Shape-of-errors-to-come.html | ||
| [volunteer effort]: https://github.com/rust-lang/rust/issues/35233 | ||
| [MIR]: https://blog.rust-lang.org/2016/04/19/MIR.html | ||
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| ## Overhauled error messages | ||
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| With 1.12 we're introducing a new error format which helps to surface a lot of | ||
| the internal knowledge about why an error is occurring to you, the developer. It | ||
| does this by focusing on your code, and the points of interest in your code that | ||
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There was a problem hiding this comment. i would put it here, but i over-comma, so 👍 |
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| are relevant to the error. | ||
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| For example, in 1.11 if a implementation of a trait didn't match the trait | ||
| declaration, you would see an error like the one below: | ||
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| In the new error format we represent the error by instead showing the points in | ||
| the code that matter the most. Here the relevant line in the trait declaration, | ||
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There was a problem hiding this comment. There's a missing word after "Here" -- "is" or "it shows"? |
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| and the relevant line in the implementation, using labels to describe why they | ||
| don't match: | ||
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There was a problem hiding this comment. Please use a screenshot which doesn't include the There was a problem hiding this comment. @jonathandturner mind sending a PR to my PR with new screenshots? |
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| Initially, this error design was built to aid borrow-checking errors, but we | ||
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| found, like the error above, the format can be broadly applied to a wide variety | ||
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| of errors. If you would like to learn more about the design, check out the | ||
| [previous blog post on the subject][err]. | ||
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| [err]: https://blog.rust-lang.org/2016/08/10/Shape-of-errors-to-come.html | ||
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| ## MIR code generation | ||
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| The new Rust "mid-level IR", usually called "MIR", gives the compiler a simpler | ||
| way to think about Rust code than it's previous way of operating entirely on the | ||
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| Rust abstract syntax tree. It makes analysis and optimizations possible that | ||
| have previously been difficult to implement correctly. The first of many | ||
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There was a problem hiding this comment. We just said "previous" in the sentence prior. Maybe "that would otherwise have been difficult to implement correctly" There was a problem hiding this comment. giving "historically" a try |
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| upcoming changes to the compiler enabled by MIR is a rewrite of the pass that | ||
| generates LLVM IR, what `rustc` calls "translation", and after many months of | ||
| effort the MIR-based backend has proved itself ready for prime-time. | ||
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| TODO: Improve code complexity: size of old trans vs size of new trans. | ||
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| While for the most part this new backend is simply laying the groundwork for | ||
| future improvements, this release does include one long-awaited refinement to | ||
| the run-time representation of Rust types that results in both compile-time wins | ||
| and runtime wins: the removal of "drop flags", AKA "non-zeroing drop", as | ||
| specified in [RFC 320]. | ||
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| To maintain the semantics of Rust's `Drop` implementation, we always need to | ||
| check whether a type must be dropped when it goes out of scope. Historically, | ||
| this has been done by adding a special flag to all types that implement `Drop`, | ||
| but this resulted in significant extra memory being used at runtime. | ||
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There was a problem hiding this comment. This paragraph and the one before need to go (although you can say that MIR doesn't need to fill memory with a specific byte pattern to know when to drop values), as the full removal of old trans and drop flags is only in 1.13. There was a problem hiding this comment. @eddyb - we saw the compile time performance from perf.rust-lang.org. How would you describe what happened between 1.11 and 1.12 to improve compile-time performance? There was a problem hiding this comment. The MIR backend is barely faster - however it's possible some of @nikomatsakis performance improvements to type/trait-related instrumentation to be in there, warrants further investigation. There was a problem hiding this comment. I am removing these paras but we should talk about it. |
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| MIR exposes perfect information about the program's control flow, so the | ||
| compiler knows exactly whether types are moved or not, in which case it knows | ||
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| statically whether or not the value's destructor needs to be run. In cases where | ||
| a value may or may not be moved at the end of a scope, the compiler now simply | ||
| uses a single bitflag on the stack, which is in turn easier for optimization | ||
| passes in LLVM to reason about. The end result is less work for the compiler and | ||
| less bloat at runtime. | ||
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| The improvements in compile times of some workloads due to this change alone are | ||
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There was a problem hiding this comment. Does "this change" refer to static drop, or to MIR trans? There was a problem hiding this comment. @brson mentioned yesterday this was from the non-zeroing drop. Brian, can we confirm that? |
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| significant: | ||
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There was a problem hiding this comment. We may also want to say something to the effect "though not all workloads will see these improvements" or something to help set expectations. I don't want people to be like "but 1.12 doesn't compile my codebase 4.5x faster :( :(" |
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| ``` | ||
| 1.11 1.12 % change (compile time) | ||
| inflate-0.1.0 10.17s 4.32s -57.5% | ||
| hyper.0.5.0 24.03s 5.23s -78.2% | ||
| helloworld 0.17s 0.14s -16.4% | ||
| regex.0.1.30 9.63s 2.39s -75.2% | ||
| ``` | ||
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There was a problem hiding this comment. We were thinking of this being a table. We may also want to turn the negative percentages into a column called "compile time" and change the percentage to a multiplier of improvement. Maybe something like: 2.35x faster |
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| TODO: Future improvements. | ||
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| TODO: non-zeroing drop PR https://github.com/rust-lang/rust/pull/33622 | ||
| https://irccloud.mozilla.com/pastebin/qqGY34SK | ||
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| [RFC 320]: https://github.com/rust-lang/rfcs/blob/master/text/0320-nonzeroing-dynamic-drop.md | ||
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| #### Library stabilizations | ||
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| See the [detailed release notes][notes] for more. | ||
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| #### Cargo features | ||
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| See the [detailed release notes][notes] for more. | ||
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| ### Contributors to 1.12.0 | ||
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| We had 176 individuals contribute to 1.12.0. Thank you so much! | ||
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There was a problem hiding this comment. Do we want to point out how many more people are in this one than before? Looking at 1.11 we had 126 and 1.10 had 139. It's not like an order of magnitude more, but the bump is noticeable at least. There was a problem hiding this comment. I am of two minds. It will then be conspicuously absent in the future 😉 |
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| * Aaron Gallagher | ||
| * abhi | ||
| * Adam Medziński | ||
| * Ahmed Charles | ||
| * Alan Somers | ||
| * Alexander Altman | ||
| * Alexander Merritt | ||
| * Alex Burka | ||
| * Alex Crichton | ||
| * Amanieu d'Antras | ||
| * Andrea Pretto | ||
| * Andre Bogus | ||
| * Andrew | ||
| * Andrew Cann | ||
| * Andrew Paseltiner | ||
| * Andrii Dmytrenko | ||
| * Antti Keränen | ||
| * Aravind Gollakota | ||
| * Ariel Ben-Yehuda | ||
| * Bastien Dejean | ||
| * Ben Boeckel | ||
| * Ben Stern | ||
| * bors | ||
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There was a problem hiding this comment. bots are people too! @bors has been credited in every release so far. They work really hard! |
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| * Brendan Cully | ||
| * Brett Cannon | ||
| * Brian Anderson | ||
| * Bruno Tavares | ||
| * Cameron Hart | ||
| * Camille Roussel | ||
| * Cengiz Can | ||
| * CensoredUsername | ||
| * cgswords | ||
| * Chiu-Hsiang Hsu | ||
| * Chris Stankus | ||
| * Christian Poveda | ||
| * Christophe Vu-Brugier | ||
| * Clement Miao | ||
| * Corey Farwell | ||
| * CrLF0710 | ||
| * crypto-universe | ||
| * Daniel Campbell | ||
| * David | ||
| * [email protected] | ||
| * Diggory Blake | ||
| * Dominik Boehi | ||
| * Doug Goldstein | ||
| * Dridi Boukelmoune | ||
| * Eduard Burtescu | ||
| * Eduard-Mihai Burtescu | ||
| * Evgeny Safronov | ||
| * Federico Ravasio | ||
| * Felix Rath | ||
| * Felix S. Klock II | ||
| * Fran Guijarro | ||
| * Georg Brandl | ||
| * ggomez | ||
| * gnzlbg | ||
| * Guillaume Gomez | ||
| * hank-der-hafenarbeiter | ||
| * Hariharan R | ||
| * Isaac Andrade | ||
| * Ivan Nejgebauer | ||
| * Ivan Ukhov | ||
| * Jack O'Connor | ||
| * Jake Goulding | ||
| * Jakub Hlusička | ||
| * James Miller | ||
| * Jan-Erik Rediger | ||
| * Jared Manning | ||
| * Jared Wyles | ||
| * Jeffrey Seyfried | ||
| * Jethro Beekman | ||
| * Jonas Schievink | ||
| * Jonathan A. Kollasch | ||
| * Jonathan Creekmore | ||
| * Jonathan Giddy | ||
| * Jonathan Turner | ||
| * Jorge Aparicio | ||
| * José manuel Barroso Galindo | ||
| * Josh Stone | ||
| * Jupp Müller | ||
| * Kaivo Anastetiks | ||
| * kc1212 | ||
| * Keith Yeung | ||
| * Knight | ||
| * Krzysztof Garczynski | ||
| * Loïc Damien | ||
| * Luke Hinds | ||
| * Luqman Aden | ||
| * m4b | ||
| * Manish Goregaokar | ||
| * Marco A L Barbosa | ||
| * Mark Buer | ||
| * Mark-Simulacrum | ||
| * Martin Pool | ||
| * Masood Malekghassemi | ||
| * Matthew Piziak | ||
| * Matthias Rabault | ||
| * Matt Horn | ||
| * mcarton | ||
| * M Farkas-Dyck | ||
| * Michael Gattozzi | ||
| * Michael Neumann | ||
| * Michael Rosenberg | ||
| * Michael Woerister | ||
| * Mike Hommey | ||
| * Mikhail Modin | ||
| * mitchmindtree | ||
| * mLuby | ||
| * Moritz Ulrich | ||
| * Murarth | ||
| * Nick Cameron | ||
| * Nick Massey | ||
| * Nikhil Shagrithaya | ||
| * Niko Matsakis | ||
| * Novotnik, Petr | ||
| * Oliver Forral | ||
| * Oliver Middleton | ||
| * Oliver Schneider | ||
| * Omer Sheikh | ||
| * Panashe M. Fundira | ||
| * Patrick McCann | ||
| * Paul Woolcock | ||
| * Peter C. Norton | ||
| * Phlogistic Fugu | ||
| * Pietro Albini | ||
| * Rahiel Kasim | ||
| * Rahul Sharma | ||
| * Robert Williamson | ||
| * Roy Brunton | ||
| * Ryan Scheel | ||
| * Ryan Scott | ||
| * saml | ||
| * Sam Payson | ||
| * Samuel Cormier-Iijima | ||
| * Scott A Carr | ||
| * Sean McArthur | ||
| * Sebastian Thiel | ||
| * Seo Sanghyeon | ||
| * Shantanu Raj | ||
| * ShyamSundarB | ||
| * silenuss | ||
| * Simonas Kazlauskas | ||
| * srdja | ||
| * Srinivas Reddy Thatiparthy | ||
| * Stefan Schindler | ||
| * Stephen Lazaro | ||
| * Steve Klabnik | ||
| * Steven Fackler | ||
| * Steven Walter | ||
| * Sylvestre Ledru | ||
| * Tamir Duberstein | ||
| * Terry Sun | ||
| * TheZoq2 | ||
| * Thomas Garcia | ||
| * Tim Neumann | ||
| * Timon Van Overveldt | ||
| * Tobias Bucher | ||
| * Tomasz Miąsko | ||
| * trixnz | ||
| * Tshepang Lekhonkhobe | ||
| * ubsan | ||
| * Ulrik Sverdrup | ||
| * Vadim Chugunov | ||
| * Vadim Petrochenkov | ||
| * Vincent Prouillet | ||
| * Vladimir Vukicevic | ||
| * Wang Xuerui | ||
| * Wesley Wiser | ||
| * William Lee | ||
| * Ximin Luo | ||
| * Yojan Shrestha | ||
| * Yossi Konstantinovsky | ||
| * Zack M. Davis | ||
| * Zhen Zhang | ||
| * 吴冉波 | ||
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Ha! I think brson put this in as a joke. I don't mind something fun here since there is a lot of stuff in this release, but maybe "Oh my god!" is a step too far.
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Yeah, I just imported the raw text for now 😄 I've just pushed a commit that re-works the intro a bit.