Clippy lints / Pedantic
Clippy lint · Pedantic · checked with Clippy 0.1.99
clippy::stable_sort_primitive: used `sort` on primitive type `i32`
What it meansWhen sorting primitive values (integers, bools, chars, as well as arrays, slices, and tuples of such items), it is typically better to use an unstable sort than a stable sort. It is in the pedantic group and off by default.
What you see
warning: used `sort` on primitive type `i32` --> main.rs:4:1 | 4 | vec.sort(); | ^^^^^^^^^^ help: try: `vec.sort_unstable()` | = note: an unstable sort typically performs faster without any observable difference for this data type = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#stable_sort_primitive = note: `-W clippy::stable-sort-primitive` implied by `-W clippy::pedantic`
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?
Typically, using a stable sort consumes more memory and cpu cycles. Because values which compare equal are identical, preserving their relative order (the guarantee that a stable sort provides) means nothing, while the extra costs still apply.
Stricter lints with some false positives. Off by default; opt in with clippy::pedantic.
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 mut vec = vec![2, 1, 3];
vec.sort();
Write this instead
let mut vec = vec![2, 1, 3];
vec.sort_unstable();
Turn it off, or on
It is off by default. To use it, set it to warn or deny:
Whole crate (Cargo.toml)
[lints.clippy]
stable_sort_primitive = "warn"In code
#![warn(clippy::stable_sort_primitive)]One run
cargo clippy -- -W clippy::stable-sort-primitiveThe [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
When sorting primitive values (integers, bools, chars, as well as arrays, slices, and tuples of such items), it is typically better to use an unstable sort than a stable sort.
Why is this bad?
Typically, using a stable sort consumes more memory and cpu cycles. Because values which compare equal are identical, preserving their relative order (the guarantee that a stable sort provides) means nothing, while the extra costs still apply.
Known problems
As pointed out in issue #8241, a stable sort can instead be significantly faster for certain scenarios (eg. when a sorted vector is extended with new data and resorted).
For more information and benchmarking results, please refer to the issue linked above.
Example
let mut vec = vec![2, 1, 3];
vec.sort();
Use instead:
let mut vec = vec![2, 1, 3];
vec.sort_unstable();
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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