Linter: plan for type checked rules?

[JoshuaKGoldberg]

Forking from #503: do you have a plan for type including type information in rules, equivalent to typescript-eslint's Linting with Type Information? E.g. integrating with https://github.com/dudykr/stc, or calling to TypeScript itself?

For reference, in typescript-eslint we've found that many of the more impactful rules have to be informed by type information. Not having it is a blocker for me and many others against using oxc for linting.

[Boshen]

From what I have seen so far from larger internal projects, people stopped using type-checking rules due to its horrible performance, and non type-checking rules' performance are just bearable 😞

There is currently no way I can implement type-checking rules by invoking tsc APIs without degrading performance.

An approach I may try in the future is to re-use the type synthesis information from the ezno type checker. We already have some of the code here https://github.com/Boshen/oxc/tree/main/crates/oxc_type_synthesis

p.s I once tried porting the type inference part of tsc to Rust, and failed obviously.

[JoshuaKGoldberg]

Oop, sorry, missed this notification a month ago - just seeing it now.

From what I have seen so far from larger internal projects, people stopped using type-checking rules due to its horrible performance, and non type-checking rules' performance are just bearable 😞

🤔 I would like to push back against that. We've been talking with quite a few teams -e.g. Bloomberg, cc @acutmore to keep me honest- that have successfully used type-checking rules. A much smaller example is https://github.com/typescript-eslint/typescript-eslint with .ts files in the range of around two thousand. Some of the common performance issues are documented on https://typescript-eslint.io/linting/troubleshooting/performance-troubleshooting.

I understand if this is out of scope for the project for now. The TypeScript type checker is indeed at JavaScript-speed and nobody's managed to get a fully working native-speed equivalent yet. But I just want to be clear that type checked rules are a feature many teams successfully use in today's systems, not an unusual edge case. 🙂

[Boshen]

Nobody is against running type checking rules. The reality for large projects (in house monorepos with files in the >10k range) is that CI time goes from a few minutes to >30 minutes.

I'm still persuading @kaleidawave to get no-floating-promises working as the next prototype, we still have chances to push things forward!