[ER] Useless slicing warning

[leonardo-m]

What it does

Inspired by this issue:
rust-lang/rust#91625

In code like this:

fn main() {
    let s = "abc".to_string();
    let t = s.strip_prefix(&['a', 'x'][..]);
    println!("{:?}", t);
}

Clippy could suggest to write instead:

s.strip_prefix(&['a', 'x'])

Or even:

s.strip_prefix(['a', 'x'])

Lint Name

No response

Category

No response

Advantage

No response

Drawbacks

No response

Example

<code>

Could be written as:

<code>

[est31]

Another example where there should be a lint:

fn foo(_v: &[u8]) {}

fn main() {
    let v = vec![1, 2, 3, 4];
    foo(&v[..]);
}

[giraffate]

We have the redundant_slicing lint, so it would be better to improve this.

[giraffate]

Clippy could suggest to write instead:

s.strip_prefix(&['a', 'x'])

It causes a compile error with currently stable 1.57.0, not beta and nightly.

[est31]

FTR, this doesn't trigger the lint either:

#![forbid(clippy::redundant_slicing)]
fn foo(_v: &[u8]) {}

fn main() {
    foo(&[1, 2, 3, 4][..]);
}

And the version without the [..] compiles on stable.