rust-lang / rust-lang/rust-clippy
New lint: Use `Into`/`TryInto` in bounds as opposed to `From`/`TryFrom`
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A-lint
good first issue
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- Rust
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Description
When writing generic bounds such as:
fn foo<T>(a: T) where u32: From<T>;
Into should be preferred, like this:
fn foo<T>(a: T) where T: Into<u32>;
Why the former is bad: Into is a superset of From. In some cases coherence rules prevent implementing From but do allow implementing Into. As a result Into is more generic bound than From.
Category: Style, I guess?
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
Start with the generic-bound examples in the issue and inspect existing Rust Clippy lint implementations and tests for similar style checks. The work is complete when bounds using From or TryFrom are detected and the lint recommends the corresponding Into or TryInto form, with coverage for the examples shown.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- devtools
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100