Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::chunks_exact_to_as_chunks: using `chunks_exact` with a constant chunk size
What it meansChecks for usage of chunks_exact or chunks_exact_mut with a constant chunk size. It is in the style group and warns by default.
What you see
warning: using `chunks_exact` with a constant chunk size --> main.rs:4:20 | 4 | let mut it = slice.chunks_exact(2); | ^^^^^^^^^^^^^^^ | help: consider using `as_chunks::<2>()` instead --> main.rs:4:20 | 4 | let mut it = slice.chunks_exact(2); | ^^^^^^^^^^^^^^^ = note: you can access the chunks using `it.0.iter()`, and the remainder using `it.1` = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#chunks_exact_to_as_chunks = note: `#[warn(clippy::chunks_exact_to_as_chunks)]` on by default
Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.
Does it matter?
as_chunks provides better ergonomics and type safety by returning arrays instead of slices. It was stabilized in Rust 1.88.
Code that works but is not idiomatic Rust. Warns by default.
How to fix it
Clippy can fix this one for you: run cargo clippy --fix (add --allow-dirty if you have uncommitted changes). Review the diff before you commit.
Flagged
let slice = [1, 2, 3, 4, 5, 6];
let mut it = slice.chunks_exact(2);
for chunk in it {}
Write this instead
let slice = [1, 2, 3, 4, 5, 6];
let (chunks, remainder) = slice.as_chunks::<2>();
for chunk in chunks {}
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::chunks_exact_to_as_chunks)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
chunks_exact_to_as_chunks = "allow"One run
cargo clippy -- -A clippy::chunks-exact-to-as-chunksThe [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.
Clippy's own documentation
What it does
Checks for usage of chunks_exact or chunks_exact_mut with a constant chunk size.
Why is this bad?
as_chunks provides better ergonomics and type safety by returning arrays instead of slices.
It was stabilized in Rust 1.88.
Example
let slice = [1, 2, 3, 4, 5, 6];
let mut it = slice.chunks_exact(2);
for chunk in it {}
Use instead:
let slice = [1, 2, 3, 4, 5, 6];
let (chunks, remainder) = slice.as_chunks::<2>();
for chunk in chunks {}
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
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All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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