feat(lint): add the ignoreRestSiblings option for lint/correctness/noUnusedVariables

[iamakulov]

Summary

This pull request adds an ignoreRestSiblings option for lint/correctness/noUnusedVariables. The option is similar to its ESLint alternative: https://eslint.org/docs/latest/rules/no-unused-vars#ignorerestsiblings

The option defaults to true (unlike its ESLint alternative) to avoid introducing a breaking change. (I’d love it if we could flip the default to false in the next major – as that would allow stricter linting by default – but this is not my call to make.)

Closes: #5152

Note: I have zero experience with Rust, so I had to Cursor my way through this PR. The (new) tests do pass, but sorry if there are any glaring omissions!

Test Plan

Tests should pass, I guess?

[ematipico]

@Conaclos what do you think about the default value?

[iamakulov]

Thanks for approving the CI run! I fixed linting/formatting checks. Two jobs (codegen and tests) are still falling.

Codegen

Codegen is obvious – but I can’t run it locally due to a silly error (which I can’t figure out how to fix), so I’d appreciate if you can do it:

$ cargo codegen-configuration
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.52s
     Running `target/debug/xtask_codegen configuration`
> rustfmt --version
rustfmt 1.8.0
Error: Failed to run rustfmt from toolchain 'stable'. Please run `rustup component add rustfmt --toolchain stable` to install it.

$ rustup component add rustfmt --toolchain stable
info: component 'rustfmt' for target 'aarch64-apple-darwin' is up to date

$ which rustfmt
/opt/homebrew/bin/rustfmt

Tests

I’m not sure why there’s such a diff between local and CI test runs, but I’m happy to hand-fix the snapshots if you say this is expected:

[ematipico]

Can you please add a changeset?

[ematipico]

$ which rustfmt
/opt/homebrew/bin/rustfmt

I don't usually use brew to handle rust on my machine. Rust has a tool called rustup that does everything without problems. https://www.rust-lang.org/tools/install

[iamakulov]

I don't usually use brew to handle rust on my machine. Rust has a tool called rustup that does everything without problems. https://www.rust-lang.org/tools/install

Thanks! Replacing the brew-installed rust and rustup with the full version helped. I updated the codegen + addressed the review feedback.

[Conaclos]

what do you think about the default value?

I think it makes sense of turning off ignoreRestSiblings by default.
This will match the behavior of ESLint (easier migration).
Also, restructuring and ignoring some properties seems as an edge case to me.
Making it opt-in seems the good call.

[Conaclos]

I wonder if we could add a note indicating that users can ignore rest sibling with the ignoreRestSiblings option.
This could improve option discovery.
We could display this note only for rest siblings like in the current case.

[codspeed-hq]

CodSpeed Performance Report

Merging #5157 will not alter performance

_{Comparing iamakulov:no-unused-vars-rest (996fa33) with main (d739883)}

Summary

✅ 94 untouched benchmarks