propose 2025h2 Goals #3849

nikomatsakis · 2025-08-15T21:56:34Z

Per https://blog.rust-lang.org/inside-rust/2025/06/23/project-goals-2025h2-call-for-submissions/, here is the proposed slate of 2025H2 goals.

Rendered

nikomatsakis · 2025-08-15T22:08:51Z

As in prior rounds, we'll follow an unusual FCP process here. Leads must check their boxes, others are encouraged but not required to do so.

bootstrap

cargo

compiler

crates-io

infra

lang

lang-docs

leadership-council

libs

libs-api

opsem

project-exploit-mitigations

@rcvalle (required, lead)
1c3t3a (optional)
cuviper (optional)

rustdoc

spec

testing-devex

types

wg-compiler-performance

wg-mir-opt

text/0000-Project-Goals-2025h2.md

Co-authored-by: Eric Holk <eric@theincredibleholk.org>

eholk · 2025-08-15T22:52:36Z

I love seeing how many goals are like "this builds on work from previous goals," or "this goal resolves blockers discovered in previous goals." It shows the goal program has been going long enough that it's starting to build some momentum throughout the project.

ehuss · 2025-08-16T01:00:03Z

Similar to last time, I would recommend changing leadership-council to not be optional.

Kobzol

Great job! Looks really good.

Kobzol · 2025-08-16T07:10:07Z

text/0000-Project-Goals-2025h2.md

+| [Production-ready cranelift backend](https://rust-lang.github.io/rust-project-goals/2025h2/production-ready-cranelift.html) | [Folkert de Vries][] | [compiler], [wg-compiler-performance]                        |
+
+
+The "Flexible, fast(er) Rust builds" initiative focuses on improving Rust's build system to better serve both specialized use cases and everyday development workflows:


What does "Rust's build system" mean? It sounds like the goal is to improve bootstrap 😅 Maybe something like "focuses on improving compilation of Rust programs ..."?

Cargo is rust's canonical build system. Absolutely no doubt in my mind it means "improving cargo"

Huh, that didn't even cross my mind. Maybe if it was "Rust build system", but "Rust's build system" sounds to me like it builds Rust, not builds Rust programs. Anyway, apart from build-std, these improvements are not Cargo specific.

Let me rephrase for greater clarity!

weihanglo · 2025-08-16T09:58:25Z

text/0000-Project-Goals-2025h2.md

+[Tomas Sedovic]: https://github.com/tomassedovic
+[TC]: https://github.com/traviscross
+[Weihang Lo]: https://github.com/weihanglo
+[@whlo]: https://github.com/whlo


Some of my handle are wrong.

@whlo should be either Weihang Lo or @weihanglo.

rust-lang/rust-project-goals#375

D'oh! Thanks.

nikomatsakis · 2025-08-16T11:49:12Z

Similar to last time, I would recommend changing leadership-council to not be optional.

So, that falls out from not having a lead. I can definitely tweak the script but I'm curious to hear your reasoning on that. Is it because you think the LC should generally be aligned on the "goal slate overall" or is it related to the Vision Doc goal, which is the only one that cited the LC.

ehuss · 2025-08-16T13:24:48Z

LC should generally be aligned on the "goal slate overall" or is it related to the Vision Doc goal, which is the only one that cited the LC.

Just the Vision Doc goal. It's just a formality, since I believe we've already says "yes" to it. I would just like to be careful with teams that don't have a lead to avoid things slipping through without consensus. Last time there were goals we weren't even aware of, so it was a bit different.

nikomatsakis · 2025-08-16T20:42:14Z

@ehuss ok, I'll make the change

text/0000-Project-Goals-2025h2.md

Mark-Simulacrum · 2025-08-17T20:38:02Z

text/0000-Project-Goals-2025h2.md

+| [Production-ready cranelift backend](https://rust-lang.github.io/rust-project-goals/2025h2/production-ready-cranelift.html) | \*1 |
+
+
+\*1: track and show `rustc_codegen_cranelift` performance ([from here](https://rust-lang.github.io/rust-project-goals/2025h2/production-ready-cranelift.html))


Can we clarify whether this means wg-compiler-performance owning the implementation and deployment work? I think the ongoing project from Arm on adding aarch64 (https://rust-lang.github.io/rust-project-goals/2025h1/perf-improvements.html) is probably a pre-requisite or at least strongly related to this.

I don't think the team as-is can commit to this happening without outside contributions (including potentially a funding ask from the Foundation, depending on how long the additional tests take -- presumably just limited to the dev profile?).

If we can just switch to cranelift only that's much easier to pull off though.

The linked rustc-perf project is 100% a pre-requisite for this. That being said, I expect it to be prepared for deployment in 2-3 months, so it should coincide with the Cranelift project fine, I think.

Once the new rustc-perf scheme lands, we will be able to do Cranelift benchmarks on demand on arbitrary PRs (it will backfill the missing results for the parent commit, which doesn't happen now).

If we want to automatically run Clif on each perf. run by default, that's also doable, we'd "just" need to buy a second perf. machine on Hetzner.

text/0000-Project-Goals-2025h2.md

1c3t3a · 2025-08-18T10:49:06Z

text/0000-Project-Goals-2025h2.md

+| [Prototype a new set of Cargo "plumbing" commands](https://rust-lang.github.io/rust-project-goals/2025h2/cargo-plumbing.html)                                      | ![Help Wanted][] | [cargo]                                                                               |
+| [Stabilize cargo-script](https://rust-lang.github.io/rust-project-goals/2025h2/cargo-script.html)                                                                  | [Ed Page][]           | [cargo] ([Ed Page][]), [compiler], [lang] ([Josh Triplett][]), [lang-docs] ([Josh Triplett][])     |
+| [Continue resolving `cargo-semver-checks` blockers for merging into cargo](https://rust-lang.github.io/rust-project-goals/2025h2/cargo-semver-checks.html)         | [Predrag Gruevski][]      | [cargo] ([Ed Page][]), [rustdoc] ([Alona Enraght-Moony][])                                          |
+| [Emit Retags in Codegen](https://rust-lang.github.io/rust-project-goals/2025h2/codegen_retags.html)                                                                | [Ian McCormack][]        | [compiler] ([Ralf Jeffery][]), [opsem] ([Ralf Jeffery][])                                                 |


I can only guess that this means @RalfJung instead of Ralf Jeffery (ralfj@ on GH)? cc: @icmccorm.

Yes—that was a typo, thanks!

Whoops, let me see if I can fix that :)

davidtwco · 2025-08-18T12:16:00Z

text/0000-Project-Goals-2025h2.md

+* [Polonius](https://rust-lang.github.io/rust-project-goals/2025h2/./polonius.html) will enable new borrowing patterns, and in particular [unblock "lending iterators"](https://github.com/rust-lang/rust/issues/92985). Over the last few goal periods we have identified an "alpha" vesion of polonius that addresses the most important cases while being relatively simple and optimizable. Our goal for 2025H2 is to implement this algorithm in a form that is ready for stabilization in 2026.
+* The [next gen trait solver](https://rust-lang.github.io/rust-project-goals/2025h2/./next-solver.html) is a refactored trait solver that unblocks better support for numerous language features (implied bounds, negative impls, the list goes on) in addition to closing a number of existing bugs and unsoundnesses. Over the last few goal periods, the trait solver went from early prototype to being production use in coherence. The goal for 2025H2 is to prepare it for use throughout the compiler.
+* The work on [evolving trait hierarchies](https://rust-lang.github.io/rust-project-goals/2025h2/./evolving-traits.html) will make it possible to refactor some parts of an existing trait out into a new supertrait so they can be used on their own. This unblocks a number of features where the existing trait is insufficiently general, in particular stabilizing support for custom receiver types, a prior project goal that wound up blocking on this refactoring.
+* The work to [expand Rust's `Sized` hierarchy](https://rust-lang.github.io/rust-project-goals/2025h2/./scalable-vectors.html) will permit us to express types that are neither `Sized` nor `?Sized`, such as extern types (which have no size) or ARM's Scalable Vector Extensions (which have a size that is known at runtime, but not compilation time). This goal builds on [RFC #3729](https://github.com/rust-lang/rfcs/pull/3729)[] and [RFC #3838](https://github.com/rust-lang/rfcs/pull/3838)[], authored in previous project goal periods.


Suggested change

* The work to [expand Rust's `Sized` hierarchy](https://rust-lang.github.io/rust-project-goals/2025h2/./scalable-vectors.html) will permit us to express types that are neither `Sized` nor `?Sized`, such as extern types (which have no size) or ARM's Scalable Vector Extensions (which have a size that is known at runtime, but not compilation time). This goal builds on [RFC #3729](https://github.com/rust-lang/rfcs/pull/3729)[] and [RFC #3838](https://github.com/rust-lang/rfcs/pull/3838)[], authored in previous project goal periods.

* The work to [expand Rust's `Sized` hierarchy](https://rust-lang.github.io/rust-project-goals/2025h2/./scalable-vectors.html) will permit us to express types that are neither `Sized` nor `?Sized`, such as extern types (which have no size) or Arm's Scalable Vector Extension (which have a size that is known at runtime, but not compilation time). This goal builds on [RFC #3729](https://github.com/rust-lang/rfcs/pull/3729)[] and [RFC #3838](https://github.com/rust-lang/rfcs/pull/3838)[], authored in previous project goal periods.

@davidtwco I merged some changes to this text, can you double check ?

petrochenkov · 2025-08-18T16:02:07Z

text/0000-Project-Goals-2025h2.md

+
+[Bastian Kersting]: https://github.com/1c3t3a
+[Amanieu d'Antras]: https://github.com/Amanieu
+[@BN]: https://github.com/BN


This is supposed to be https://github.com/b-naber.

petrochenkov · 2025-08-18T16:02:56Z

text/0000-Project-Goals-2025h2.md

+[Guillaume Gomez]: https://github.com/GuillaumeGomez
+[James]: https://github.com/Jamesbarford
+[Pete LeVasseur]: https://github.com/PLeVasseur
+[Ralf Jeffery]: https://github.com/RalfJ


This is supposed to be https://github.com/RalfJung.

petrochenkov · 2025-08-18T16:03:30Z

text/0000-Project-Goals-2025h2.md

+[Aapo Alasuutari]: https://github.com/aapoalas
+[Alona Enraght-Moony]: https://github.com/adotinthevoid
+[Jon Bauman]: https://github.com/baumanj
+[@boxy]: https://github.com/boxy


-> https://github.com/boxyuwu

petrochenkov · 2025-08-18T16:04:35Z

text/0000-Project-Goals-2025h2.md

+[Folkert de Vries]: https://github.com/folkertdev
+[Frank King]: https://github.com/frank-king
+[Ian McCormack]: https://github.com/icmccorm
+[Tugce Ciftci]: https://github.com/imperio


-> https://github.com/GuillaumeGomez

petrochenkov · 2025-08-18T16:05:15Z

text/0000-Project-Goals-2025h2.md

+[Ian McCormack]: https://github.com/icmccorm
+[Tugce Ciftci]: https://github.com/imperio
+[Jack Huey]: https://github.com/jackh726
+[@jackwrenn]: https://github.com/jackwrenn


-> https://github.com/jswrenn

Thank you :)

RalfJung · 2025-08-19T12:21:29Z

text/0000-Project-Goals-2025h2.md

+| [In-place initialization](https://rust-lang.github.io/rust-project-goals/2025h2/in-place-initialization.html)                                                      | [Alice Ryhl][]        | [lang] ([Taylor Cramer][])                                                                    |
+| [C++/Rust Interop Problem Space Mapping](https://rust-lang.github.io/rust-project-goals/2025h2/interop-problem-map.html)                                           | [Jon Bauman][]         | [compiler] ([Oliver Scherer][]), [lang] ([Tyler Mandry][]), [libs] ([David Tolnay][]), [opsem]                  |
+| [Finish the libtest json output experiment](https://rust-lang.github.io/rust-project-goals/2025h2/libtest-json.html)                                               | [Ed Page][]           | [cargo] ([Ed Page][]), [libs-api], [testing-devex]                                         |
+| [MIR move elimination](https://rust-lang.github.io/rust-project-goals/2025h2/mir-move-elimination.html)                                                            | [Amanieu d'Antras][]         | [compiler], [lang] ([Amanieu d'Antras][]), [opsem], [wg-mir-opt]                                  |


Amanieu is not in t-lang though, so... what does this row mean?

He's an advisor.

Co-authored-by: Josh Triplett <josh@joshtriplett.org>

Co-authored-by: lcnr <rust@lcnr.de>

propose 2025h2 Goals

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nikomatsakis and others added 4 commits August 19, 2025 09:24

Update text/0000-Project-Goals-2025h2.md

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Co-authored-by: Josh Triplett <josh@joshtriplett.org>

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Co-authored-by: lcnr <rust@lcnr.de>

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		\| [Production-ready cranelift backend](https://rust-lang.github.io/rust-project-goals/2025h2/production-ready-cranelift.html) \| [Folkert de Vries][] \| [compiler], [wg-compiler-performance] \|


		The "Flexible, fast(er) Rust builds" initiative focuses on improving Rust's build system to better serve both specialized use cases and everyday development workflows:

		\| [Production-ready cranelift backend](https://rust-lang.github.io/rust-project-goals/2025h2/production-ready-cranelift.html) \| \*1 \|


		\*1: track and show `rustc_codegen_cranelift` performance ([from here](https://rust-lang.github.io/rust-project-goals/2025h2/production-ready-cranelift.html))

propose 2025h2 Goals #3849

Are you sure you want to change the base?

propose 2025h2 Goals #3849

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bootstrap

cargo

compiler

crates-io

infra

lang

lang-docs

leadership-council

libs

libs-api

opsem

project-exploit-mitigations

rustdoc

spec

testing-devex

types

wg-compiler-performance

wg-mir-opt

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eholk commented Aug 15, 2025

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nikomatsakis commented Aug 16, 2025

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nikomatsakis commented Aug 15, 2025 •

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