9 pages tagged with "rust"

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.

read more

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:

read more

We've already explored some of the dark corners of Rust semantic versioning on this blog:

read more

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.

read more

I recently embarked on a quest: revamp the cargo-semver-checks import-handling system so that moving and re-exporting an item stops being incorrectly flagged as a major breaking change. This is how crate authors can reorganize or rename items: just re-export the items in the original location under … read more

I've been saying for a while now that semantic versioning in Rust is tricky and full of unexpected edge cases. My last post mentioned that some Rust structs can be converted into enums without requiring a major version bump. It introduced a non-exhaustive struct called Chameleon that had no public f… read more

EDIT: The Rust API evolution RFC distinguishes between breaking changes and changes that require a new semver-major version (called major changes). All major changes are breaking, but not all breaking changes are major. Changing a struct to an enum is always breaking (as pointed out on r/rust) but i… read more

cargo-semver-checks ends 2022 with 40,000 downloads from crates.io, able to prevent 30 different kinds of semver issues, and having done so in real-world use cases. Inspired by Yoshua Wuyts' "Rust in 2023 (by Yosh)" post, here are my thoughts on cargo-semver-checks in 2022, and what I look… read more

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.

read more