rust-lang / rust-lang/rust-clippy

False positive for boxed local with `wasm_bindgen`

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C-bug good first issue I-false-positive
Dominant language
Rust
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Description

wasm_bindgen is a little bit different than the issue that's been resolved with traits. In particular, wasm_bindgen just generates code around the non-trait implemented function, and the only way to use native JS arrays as parameters is to use Box<[...]>.

In general, I think maybe boxed slices should be considered ok for local parameters, as they're conceptually very similar to vectors.

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Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the Clippy lint that reports boxed locals and find its existing regression tests. Reproduce the wasm_bindgen case described here, then determine whether boxed slices used as local parameters should be exempted and add coverage showing the false positive is gone.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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