How to add custom local rules?

[AdrienPoupa]

Hello!

I saw that JS Custom Rules support is planned in #9905

However I was curious to see if I could create my own local rules using Rust in the meantime. I could not find anything in the documentation. Is it possible, or are you handling custom rules support in JS first?

Thank you!

[camc314]

These are still very experimental, and have not yet been oficially released. Once we announce them there will be docs about how to implement this.

If you are still interested, take a look at our test cases >

oxc/apps/oxlint/test/fixtures/basic_custom_plugin/test_plugin/index.js

Line 16 in 53d04dd

},

[overlookmotel]

What we will soon release is support for linter plugins written in JS.

I think what you're asking is are we going to support writing rules in Rust. I believe the answer to that is no, not any time soon. But @camc314 can confirm that's correct.

[camc314]

oh yes I misread the original post. Yes @overlookmotel is correct, custom rules in rust is not planned at this time. If you have an idea for a rule, feel free to open an issue/discussion and it can then be consideredd

[AdrienPoupa]

That's what I was asking indeed. I thought it'd easier to plug a custom Rust rule than a JS one at the moment.

Our rules are very domain-specific, custom to our needs so I'm not sure it'd make sense to open a feature request.

I'm curious about why it's not considered. I'm obviously not familiar at all with Oxlint's architecture, but giving users the ability to write their Rust rules would be more performant than JS and I thought it'd only require giving the ability to give a path to a local rule?

[camc314]

I'm curious about why it's not considered. I'm obviously not familiar at all with Oxlint's architecture, but giving users the ability to write their Rust rules would be more performant than JS and I thought it'd only require giving the ability to give a path to a local rule?

We will probably consider it one day, however its a non-trivial undertaking so isn't a priority at this time. To expand more, supporting it has a few challenged:

• Dynamic Loading: Rust lacks simple, safe dynamic code loading. Supporting plugins as compiled libraries (e.g., .dylib, .so) requires users to match our exact toolchain, risking version conflicts and platform-specific issues.
• Complex API Integration: Exposing a stable, safe API for custom rules to hook into our AST traversal system involves significant work, including FFI, thread-safety, and error handling to avoid crashes.
• Security Concerns: Loading external Rust code could introduce memory safety risks or unintended behavior, requiring heavy sandboxing that might offset performance gains.

We're focused on supporting custom JS plugins at present. At a later date we might consider rust plugins.

[AdrienPoupa]

That makes sense, thanks for the thorough explanation!