Hacker News

by Ryan Harman

2026 is an exciting year for the Rust compiler (and me) (yoyo-code.com)

131 points by panstromek 8 hours ago

LoganDark 2 minutes ago

Hexcat link is broken and leads to "https://https//hexcat.nl" instead of https://hexcat.nl

throwup238 5 hours ago

> It's easy to understate how big of a deal this is for the compiler. This work resolves a major piece of technical debt that a lot of compiler developers dreamed about for years.

No kidding. I’ve been waiting for the solver at least half that decade now. Hopefully it and Polonius unblock specialization which has been in purgatory for years.

panstromek 4 hours ago

There's some movement on specialization as well: https://goals.rust-lang.org/2026/specialization.html

It's not directly blocked on the solver, but getting the type system into a better shape definitely helps reasoning about the soundness issues involved.

yhjc2692 6 hours ago

Smaller target directory size would be such a lifesaver. Hoping the best for you, and Rust!

stymaar 4 hours ago

This!

There's a recurring meme here and in other social media about rust being slow to compile, but anyone who's worked with Rust know that target dirs are a much more annoying papercut in practice than the relative speed of the compiler (which isn't appreciably worse than any other toolchain out there for the most common workflows).

anonymous908213 3 hours ago

A papercut is an unbelievable way to describe this. I tried forking Codex CLI and, for a terminal UI that manages chats and HTTP requests, it takes over 15 minutes to rebuild trivial changes on a top-shelf CPU with all incremental/caching optimizations, and tens of GBs in build caches. Neither of those is acceptable. Full stop. I am aware part of the problem is that Codex CLI is a vibe-coded monstrosity (surprise, software is not solved), but I've not had this problem with vibe-coded monstrosities in eg. Go. Hold your language to better standards. That doesn't mean abandon Rust; that means strive to make the Rust toolchain better than the Go toolchain rather than shrugging your shoulders and saying "lol this is fine no way anybody could do anything about this".

xyzzy_plugh 2 hours ago

simonask 3 hours ago

rapind 4 hours ago

Both (and memory) are a problem. Build sizes is definitely more easily solved just by throwing more disk at it though (unless you are using a hard constrained mac...).

estebank 4 hours ago

colechristensen 3 hours ago

d0mine 4 hours ago

~Zero build time Python vs 20 min for Rust web app

Filligree 3 hours ago

maccard 2 hours ago

colechristensen 3 hours ago

thomashabets2 6 hours ago

It would help, yes. Here's one of my projects, that uses different subdirectories in target/ based on compiler options pre-commit runs:

    $ du -hcs target/
    190G    target/

bitbasher 4 hours ago

I can deal with large builds, what I cant deal with is time. My rust web application takes 20 minutes to build in release mode on a high end developer machine. I can’t build it in ci/cd.

rapind 4 hours ago

panstromek 3 hours ago

simonask 4 hours ago

MBCook 4 hours ago

Could you e plain the issue for a non-rustacean?

estebank 3 hours ago

The Rust toolchain by default produces a lot of debug information for each crate being compiled and the language relies heavily on monomorphization (instantiating a different function/type for each combination of generics) which translates to generally having duplicated functionality where the only difference in the object code is the different types. These two things combined, along with large dependency trees and that "features" for conditional compilation cause the same crate to be considered different across different workspaces (meaning the rlibs that were created for one can't be reused for another), means that the target directory for Rust projects can quickly grow. That, + clippy not having stabilized an already implemented process to automatically delete files from the target directory when they are unlikely to be needed again (which can't be 100% accurate, it uses heuristics because a developer could always potentially need an exact rlib from 6 months ago, it is just unlikely) means that you can expect that under the default configuration your target directory ends up being huge after a short period of time.

A lot of those things are in different stages of being fixed. I would personally want the default for generated debug information to be changed. cargo gc will help with running out of disk space. Better cross-project reuse of existing rlibs could be accomplished with some better tracking of optional features that can be unified (think having `serde` with feature `derive` enabled in one project, and having it without it in another: features are supposed to be purely additive, so you could reuse the earlier rlib on the later, but in practice people (ab?)use features in non-additive ways so it isn't straighforward to do something like that by default). Tools like hakari lets you create workspace-unified Cargo.toml to emulate this behavior.

yhjc2692 2 hours ago

KolmogorovComp 18 minutes ago

I'm wondering about the future of clippy.

infogulch an hour ago

I'm curious about polymorphism. Should it be default on for debug builds just to save storage and compile time? How will rust decide whether to enable polymorphism? Will it be possible to provide source-level polymorphism hints to the compiler?

estebank an hour ago

The "hint" you could provide today for polymorphization is to write code like

    fn needs_string_like(x: Into<String>) {
        fn actual_logic(_: String) {}
        actual_logic(x.into())
    }
which is the explicit way of representing the same thing rustc would be doing automatically. The above will create an almost empty `needs_string_like` for each type that it is called with, but a single `actual_logic`. IIRC some optimization passess would completely remove specific instances of `needs_string_like` (like if you call `needs_string_like(String::new())`).

panstromek 22 minutes ago

> polymorphism

I assume you ask about polymorphization, which is a term used to refer to a specific optimization mentioned in the blog post.

The base version which Rust wants the most makes sense to enable by default for all builds, because it's purely just removing duplicate work - this is for cases like Vec<u64> and Vec<i64>, where we currently emit code for each one separately, even though it's pretty much the same for both.

More general version will make sense for debug builds or in some special cases, like when optimizing for size. I believe people also want to experiment with it for some interop use cases (and for that, it'd be useful to have source level annotation). I think it's too early to tell how all of this is going to look like, though.

panstromek 7 hours ago

I don't understandy why, but all submissions of this post so far had incorrect title. When I posted the correct one, it still got reassigned the wrong title and I had to edit it (and it didn't allow me to do that yesterday, only today).

tialaramex 6 hours ago

Hacker News has some automatic fixes for title text. Some - perhaps all - of them can walk into false positives where a change that's usually desirable instead ruins the title either because it's a joke and the change spoils the joke or just because English is complicated.

hmokiguess 6 hours ago

Pretty wild to see how different people’s experiences can be within the same industry but under different applications and circumstances, here is someone joyful about the future of a language whereas not long ago we had a Ruby gem maintainer in deep dissatisfaction and frustration with the future of it.

Not implying to compare Rust and Ruby, just mainly observing how these two things came out near each other in the present day.

anonymous908213 3 hours ago

Leadership matters. I don't suppose the Rust leaders have been telling their community to write more open-source code for free with the express purpose of replacing those people with LLMs trained on their work.

hmokiguess 2 hours ago

On this topic, how ironic that the Ruby dude who is getting infamous for doing this is preaching moving to Rust

shmerl 15 minutes ago

Somewhat indirectly related, but is there any progress on implementing persistent caching in rust-analyzer? It would really benefit from faster startup times.

vatsachak 4 hours ago

The best way to get a rust job is get a regular job and just write rust

cpursley 3 hours ago

I did this once but with Elixir, and it worked - because I shipped ahead of schedule (way ahead of the other teams portions). Performance and quality met the standards. Sometimes it's better to ask for forgiveness than permission if that means not having to fool with Java.

vatsachak 3 hours ago

Unless you work at a FAANG the team will ask you to make a tool and will probably be fine with a mainstream language.

lolakutty 5 hours ago

Rust is not very relevant anymore when you can write it in C and once in a while run an LLM over it to catch any memory issues...

satvikpendem 5 hours ago

I hope this is satire.

lolakutty 4 hours ago

It is not. Tell me one good reason to deal with the horrible language called rust now that we have mechanisms capable of doing the exact same stuff in a vastly less obnoxious manner....(I am talking about running LLMs over your C code once in a while).

I don't like rust because

1. Verbose Syntax made worse by having to include type system info... 2. Dumb Borrow checker 3. Automagic stuff...

Sharlin 2 hours ago

esafak 34 minutes ago

ikety 4 hours ago

or to save tokens you can have an LLM write a borrow checker to do this for you. Oh wait you're just rebuilding rust...

lolakutty 4 hours ago

The point of writing in C is that I don't have to deal with borrow checker shit when it is too dumb to figure out what I want to do is actually safe.

simonask 3 hours ago