An independent software engineer applying compiler technology to the data space. I most often write about Rust, compilers, performance optimizations, and data querying technology.
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cargo-semver-checks
v0.35 can determine whether Rust traits are "sealed", allowing it to catch many tricky new instances of SemVer breakage. Why is accurate sealed trait detection so important, and why is implementing it correctly so hard?
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In 2022, I gave a talk at a virtual conference with an unforgettable name: HYTRADBOI, which stands for "Have You Tried Rubbing a Database On It?" Its goal was to discuss unconventional uses of database-like technology, and featured many excellent talks.
My talk "How to Query (Almost) Everything" received copious praise. It describes the Trustfall query engine's architecture, and includes real-world examples of how my (now-former) employer relies on it to statically catch and prevent cross-domain bugs across a monorepo with hundreds of services and shared libraries. For example:
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My last post covered the key cargo-semver-checks
achievements from 2023. Here are the biggest challenges that lie ahead!
Many of the remaining challenges in cargo-semver-checks are obvious: we all want more lints, fewer false-positives, etc. etc. Let's set those aside.
Instead, let's talk about four non-obvious challenges we have yet to tackle:
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2023 was a big year for cargo-semver-checks
! We saw ecosystem-wide adoption in projects of all shapes and sizes: the tokio
and PyO3
ecosystems, company-backed OSS projects from companies like Amazon and Google, and even in cargo
itself. Here's a look back at the highlights of 2023!
1970-01-01 08:00:00
cargo-semver-checks
v0.25 squashes nearly all bugs related to doc(hidden)
items — its most common source of false-positives. What does doc(hidden)
mean in Rust, and why was handling it correctly so hard?
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A few days ago, I started polls on Mastodon and Twitter whether adding a new private type, or an import, can ever be a major breaking change. The consensus was that this should be impossible.
I agree with that. It should be impossible.
I've discovered a way to cause a previously-public type or function to disappear from a crate's public API by making innocuous-seeming changes like adding a private type or adding an import, etc. It is not a hypothetical problem, either — I've found at least one real-world Rust project that has been affected by it.
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For the longest time, I thought that "sealed trait" in Rust was a singular concept implementable in one specific way. To prevent downstream crates from implementing your traits, you make the traits sealed — done, end of story. I was wrong! It turns out there are multiple ways to seal traits, forming a pleasant spectrum of options:
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We've already explored some of the dark corners of Rust semantic versioning on this blog:
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This post describes work in progress: how cargo-semver-checks
will benefit from the upcoming query optimization API in the Trustfall query engine. Read on to learn how a modern linter works under the hood, and how ideas from the world of databases can improve its performance.
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I recently built cargo-semver-checks
, a linter that ensures crates adhere to semantic versioning. This is why and how I built it.
Fearless development is a key theme throughout Rust. "If it compiles, it works", fearless concurrency, etc.
But there's one aspect of Rust (and nearly all other languages) that isn't entirely fearless yet: cargo update
, upgrading the versions of the project's dependencies.
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