Suggest usage of `array.as_slice()` (instead of `&array[..]`) and `array.as_mut_slice()`

[Luro02]

What it does

Lints for example this code:

let array: [u8; 4] = [1, 2, 3, 4];
let slice: &[u8] = &array[..];

and suggests array::as_slice:

let array: [u8; 4] = [1, 2, 3, 4];
let slice: &[u8] = array.as_slice();

(same should be suggested for &mut array[..], which can be replaced with array.as_mut_slice())

Categories (optional)

• Kind: clippy::pedantic or clippy::style

What is the advantage of the recommended code over the original code?

For example:

• easier to read for people new to rust (not very obvious what [..] does)
• there must be a reason why array::as_slice exists? (see Add [T; N]::as_[mut_]slice rust#76120)

Drawbacks

• might have a lot of false positives or not much benefit in using the function

Possibly related issues:

• as_slice will be stable in 1.7 #728
• Add lint on &[char] #5598

Stabilization

At the time of writing this issue, the function is still unstable, but with the merging of rust-lang/rust#88353, this feature will be stabilized. (final-comment-period, so will be merged in the next few days)

Not sure about this one. We currently suggest for x in &y { .. } over for x in y.iter() { .. } - explicit_iter_loop. This seems like it's going to the opposite direction in terms of style. Also we don't current recommend Vec::as_slice over slicing although we could have for years.

[Dmitry-Borodin]

Should this issue be implemented or it's doubtable?
I'm looking for a good first issue, and I would like to understand if this should be implemented as in original message and under which category it's better to place.

[giraffate]

IMO it looks like a good idea to implement this, but the restriction category might be better.

[nindalf]

@rustbot claim

[nindalf]

@rustbot release-assignment

As mentioned by @camsteffen in my PR, it's probably better if @Jarcho adds this lint to their PR #8218 or as a follow up.

[nils-degroot]

@rustbot claim