Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::redundant_slicing: redundant slicing of the whole range

What it meansChecks for redundant slicing expressions which use the full range, and do not change the type. It is in the complexity group and warns by default.

What you see

warning: redundant slicing of the whole range
 --> main.rs:4:5
  |
4 |     &x[..]
  |     ^^^^^^ help: use the original value instead: `x`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#redundant_slicing
  = note: `#[warn(clippy::redundant_slicing)]` 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?

It unnecessarily adds complexity to the expression.

Code that does something simple in a complicated way. 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

fn get_slice(x: &[u32]) -> &[u32] {
    &x[..]
}

Write this instead

fn get_slice(x: &[u32]) -> &[u32] {
    x
}

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

On one item

#[allow(clippy::redundant_slicing)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
redundant_slicing = "allow"

One run

cargo clippy -- -A clippy::redundant-slicing

The [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.

Complexitygroup

warndefault level

yesfixed by cargo clippy --fix

1.51.0added in Rust

Clippy's own documentation

What it does

Checks for redundant slicing expressions which use the full range, and do not change the type.

Why is this bad?

It unnecessarily adds complexity to the expression.

Known problems

If the type being sliced has an implementation of Index<RangeFull> that actually changes anything then it can’t be removed. However, this would be surprising to people reading the code and should have a note with it.

Example

fn get_slice(x: &[u32]) -> &[u32] {
    &x[..]
}

Use instead:

fn get_slice(x: &[u32]) -> &[u32] {
    x
}

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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