polonius

Defines the Rust borrow checker.

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REPOSITORY AT A GLANCE

What to know before exploring

What it is

Defines the Rust borrow checker.

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

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Also in these discussions

rust-lang/chalk · linked in 2 of the same discussions
rust-lang/datafrog · linked in 2 of the same discussions

Mentioned in the same Hacker News threads. That is not proof they are substitutes.

This week on Hacker News

Nov 8–Nov 15 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/15/2026, 10:56:20 AM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year20 dated mentions

Observed mentions: 2018-05-19 13:41:37 UTC to 2026-05-18 01:30:58 UTC.

* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges

UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
Period	Start (UTC)	End (exclusive, UTC)	Mentions	Submissions	Comments
2018	2018-01-01 00:00:00 UTC	2019-01-01 00:00:00 UTC	3	0	3
2019	2019-01-01 00:00:00 UTC	2020-01-01 00:00:00 UTC	2	0	2
2020	2020-01-01 00:00:00 UTC	2021-01-01 00:00:00 UTC	2	0	2
2021	2021-01-01 00:00:00 UTC	2022-01-01 00:00:00 UTC	1	0	1
2022	2022-01-01 00:00:00 UTC	2023-01-01 00:00:00 UTC	5	0	5
2023	2023-01-01 00:00:00 UTC	2024-01-01 00:00:00 UTC	0	0	0
2024	2024-01-01 00:00:00 UTC	2025-01-01 00:00:00 UTC	2	0	2
2025	2025-01-01 00:00:00 UTC	2026-01-01 00:00:00 UTC	3	1	2
2026 (partial)	2026-01-01 00:00:00 UTC	2027-01-01 00:00:00 UTC	2	0	2

What Hacker News says

5 sources

amaranth·Dec 14, 2022

This is eventually going to be a feature-complete compiler, targeting a specific rustc version. I believe the plan is to use polonius [1], presumably as an "optional" feature so they can build a stage 1 without it, use that to build polonius, then build the final compiler with it included. [1] https://github.com/rust-lang/polonius

In Rust front-end merged in GCC trunk

idmitrievsky·Nov 14, 2022

It looks like an official borrow checker implementation called Polonius uses it as a dependency, so it makes sense: https://github.com/rust-lang/polonius/blob/981785c101b68ff54...

In Datafrog: A lightweight Datalog engine in Rust

drewbug01·Nov 8, 2022

If you click around a little, you end up on a blog post with this tidbit: > This project got put together rather suddenly, in response to some work the Rust folks are doing[1] on their new and improved borrow checker. I don't think I could tell you more than "Frank wrote it to help rust folks who were previously doing work with differential-dataflow directly." 1. https://github.com/rust-lang/polonius/pull/36#issuecomment-3...

In Differential Datalog: a programming language for incremental computation

mjw1007·Jun 17, 2022

As I understand it, Polonius is still intended to be the next version of the borrow checker. The repostory is here: https://github.com/rust-lang/polonius There doesn't seem to have been any meaningful development for well over a year. There is some very recent discussion on Zulip which makes it look like there are at least two or three people interested in actively working on it. https://rust-lang.zulipchat.com/#narrow/stream/186049-t-comp...

In Adding a Rust compiler front end to GCC [video]

tialaramex·May 19, 2022

Sometimes, what you're doing is unsound and so it must be forbidden even if you can't intuitively see why yet. Rust's diagnostics often show you why. However, sometimes (and for an experienced Rust developer this might start to happen more often than "Oh, actually that was dumb" type situations) the problem is that the Borrow Checker doesn't understand why it's fine. The diagnostic points you at something, and you say "Er, yeah, what's the problem?" and, sometimes, there wasn't really a problem. Non-lexical lifetimes were a big improvement in Rust, improving the borrow checking analysis so that more cases which are correct were allowed by the checker. Polonius is one thing intended to further improve upon this: https://github.com/rust-lang/polonius

In The Rust Borrow Checker – A Deep Dive