Suggest to remove unneeded `.as_slice()` and similar

What it does

This lint would detect redundant Vec::as_slice() and similar calls when the resulting slice is only used to call a method that would also resolve directly on the Vec through deref coercion.

Advantage

• Cleaner, shorter, easier to read code

Drawbacks

No response

Example

All usages of .as_slice() and .as_mut_slice() can be removed. Note that as_mut_slice() is a extended case because it does not actually need mut either.

#![warn(clippy::pedantic)]

trait SliceExt {
    fn my_len(&self) -> usize;
}
impl SliceExt for [u32] {
    fn my_len(&self) -> usize {
        self.len()
    }
}
fn as_ref(vals: &mut Vec<u32>) {
    assert_eq!(vals.as_slice().len(), vals.len()); //~ as_slice() not needed
    assert_eq!(vals.as_mut_slice().len(), vals.len()); //~ as_mut_slice() not needed
}
fn as_owned_ex(mut vals: Vec<u32>) {
    assert_eq!(vals.as_slice().my_len(), vals.my_len()); //~ as_slice() not needed
    assert_eq!(vals.as_mut_slice().my_len(), vals.my_len()); //~ as_mut_slice() not needed
}
fn as_ref_ex(vals: &mut Vec<u32>) {
    assert_eq!(vals.as_slice().my_len(), vals.my_len()); //~ as_slice() not needed
    assert_eq!(vals.as_mut_slice().my_len(), vals.my_len()); //~ as_mut_slice() not needed
}
fn main() {
    as_ref(&mut vec![1_u32, 2, 3]);
    as_owned_ex(vec![1_u32, 2, 3]);
    as_ref_ex(&mut vec![1_u32, 2, 3]);
}

Comparison with existing lints

No response

Additional Context

No response