New lint: use slice.first() instead of slice.get(0)

[equal-l2]

What it does

Detects slice.get(0) and suggests replacement with slice.first().

Lint Name

slice_get_zero

Category

style

Advantage

No magic numbers.

Drawbacks

first() is longer than get(0) by 1 character.

Example

let v = vec![0, 1, 2];
println!("{}", vec.get(0));

Could be written as:

let v = vec![0, 1, 2];
println!("{}", vec.first());

[kyoto7250]

@rustbot claim

[smmoosavi]

this rule is annoying. In this code, we need the first 3 items in the list.

let path = list.get(0);
let next = list.get(1);
let other = list.get(2);

but clippy::get_first is forcing us to change the into:

let path = list.first();
let next = list.get(1);
let other = list.get(2);

which is less readable

[y21]

@smmoosavi You can also write that as let [path, next, other, ..] = &*list else { /* handle the failure case */ }; which is arguably better than both, or you can just #[allow] the lint for that let statement if you don't agree or it's not applicable.

In general, I don't think there is anything that can be done about aesthetic cases like yours. That argument can be made about pretty much almost every clippy::style lint that exists. E.g.:

let x = (collection.len() == 0).then_some(foo);
let y = (collection.len() == 1).then_some(bar);
let z = (collection.len() == 2).then_some(baz);

Clippy also suggests using is_empty on only the first one, which breaks symmetry and doesn't look as nice 🤷‍♂️