rust-lang / rust-lang/rust-clippy
`tuple_array_conversions` lint makes code less readable when slice is involved
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Description
Summary
I tried this code:
fn main() {
let (a, b) = (1.0f64, 2.0f64);
let _foo: &[f64] = &[a, b];
}
However, using .into() in this situation doesn't work, as the compiler infers the unsized type [f64]:
fn main() {
let tuple = (1.0f64, 2.0f64);
let _foo: &[f64] = &tuple.into();
}
produces:
error[[E0277]](https://doc.rust-lang.org/nightly/error_codes/E0277.html): the trait bound `[f64]: From<(f64, f64)>` is not satisfied
--> src/main.rs:3:31
|
3 | let _foo: &[f64] = &tuple.into();
| ^^^^ the trait `From<(f64, f64)>` is not implemented for `[f64]`
|
Using <[T; N]>::from works - however, IMO this code is significantly less readable:
fn main() {
let tuple = (1.0f64, 2.0f64);
let _foo: &[f64] = &<[f64; 2]>::from(tuple);
}
I would argue that the original code is the most readable in this situation (constructing a slice from a tuple), and this lint should not fire when a slice is involved.
Lint Name
tuple_array_conversions
Reproducer
I tried this code:
fn main() {
let (a, b) = (1.0f64, 2.0f64);
let _foo: &[f64] = &[a, b];
}
However, using .into() in this situation doesn't work, as the compiler infers the unsized type [f64]:
fn main() {
let tuple = (1.0f64, 2.0f64);
let _foo: &[f64] = &tuple.into();
}
produces:
error[[E0277]](https://doc.rust-lang.org/nightly/error_codes/E0277.html): the trait bound `[f64]: From<(f64, f64)>` is not satisfied
--> src/main.rs:3:31
|
3 | let _foo: &[f64] = &tuple.into();
| ^^^^ the trait `From<(f64, f64)>` is not implemented for `[f64]`
|
Version
rustc 1.72.0-nightly (839e9a6e1 2023-07-02)
binary: rustc
commit-hash: 839e9a6e1210934fd24b15548b811a97c77138fc
commit-date: 2023-07-02
host: x86_64-unknown-linux-gnu
release: 1.72.0-nightly
LLVM version: 16.0.5
Additional Labels
No response
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 by locating the tuple_array_conversions lint implementation and its existing tests, then run the Rust reproducer from the issue. Update the lint behavior so the slice-involved case is not flagged, and verify the reproducer no longer receives the readability-reducing suggestion while other tuple-to-array conversions remain covered.
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
- Mostly clear
- Newbie friendliness
- 40/100