rust-lang / rust-lang/rust-clippy
Lint for highlighting possibly invalid coercion `Box<dyn Any>` -> `&dyn Any` with implicit deref
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A-lint
- Dominant language
- Rust
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Description
What it does
Give a warning when doing possibly unwanted &dyn Any coercion from a Box
Advantage
- Less headache figuring out why the Any is of wrong type
Drawbacks
No response
Example
let b: Box<dyn Any> = ...;
// What I'd write to get a reference to the inner Any
// but instead i get a reference to the box itself
let r: &dyn Any = &b; // lint: possibly unwanted coercion
// Suggest replacing with:
let r: &dyn Any = b.deref();
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
The issue names no files or tests; start from the Rust example and locate Clippy’s entry point and test pattern for coercion lints. Done means warning on the potentially unwanted Box to &dyn Any coercion, with the suggested deref alternative covered by a test.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100