string_slice should detect on Cow

[EdJoPaTo]

Summary

When a string slice is used on a type containing the str the lint does not notice currently.
My use case is a Cow<&str> which isn't noticed by this lint.

Lint Name

string_slice

Reproducer

I tried this code:

#![warn(clippy::string_slice)]

use std::borrow::Cow;

fn main() {
    let a = Cow::Borrowed("foo");
    let b = "bar";

    let x = &a[0..2];
    let y = &b[0..2];

    dbg!(&a, &b, x, y);
}

I expected to see this happen: x and y should create a warning.

Instead, this happened: Only y creates a warning.

Version

rustc 1.77.2 (25ef9e3d8 2024-04-09)
binary: rustc
commit-hash: 25ef9e3d85d934b27d9dada2f9dd52b1dc63bb04
commit-date: 2024-04-09
host: x86_64-unknown-linux-gnu
release: 1.77.2
LLVM version: 17.0.6