False positive redundant_slicing report when slicing as immutable slice to invoke Read trait methods taking (&mut self)

[EdMcBane]

Lint name: redundant_slicing

I tried this code:

    let data = vec![1,2,3];
    let src: &[u8] = &data;
    let mut dest = vec![];
    (&src[..]).read_to_end(&mut dest).unwrap();

I expected no lint warnings, due to the fact that the slicing in the last line is needed to call read_to_end on the immutable slice src.

Instead clippy reports redundant slicing of the whole range

warning: redundant slicing of the whole range
 --> src/main.rs:6:5
  |
6 |     (&src[..]).read_to_end(&mut dest).unwrap();
  |     ^^^^^^^^^^ help: use the original value instead: `src`
  |
  = note: `#[warn(clippy::redundant_slicing)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_slicing

Consequently, cargo clippy --fix fails with:

fdegrassi@homerunner:/tmp/asd$ cargo clippy --fix
    Checking asd v0.1.0 (/tmp/asd)
warning: failed to automatically apply fixes suggested by rustc to crate `asd`

after fixes were automatically applied the compiler reported errors within these files:

  * src/main.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see 
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
error[E0596]: cannot borrow `src` as mutable, as it is not declared as mutable
 --> src/main.rs:6:5
  |
4 |     let src: &[u8] = &data;
  |         --- help: consider changing this to be mutable: `mut src`
5 |     let mut dest = vec![];
6 |     src.read_to_end(&mut dest).unwrap();
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0596`.
Original diagnostics will follow.

warning: redundant slicing of the whole range
 --> src/main.rs:6:5
  |
6 |     (&src[..]).read_to_end(&mut dest).unwrap();
  |     ^^^^^^^^^^ help: use the original value instead: `src`
  |
  = note: `#[warn(clippy::redundant_slicing)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_slicing

warning: `asd` (bin "asd") generated 1 warning
warning: `asd` (bin "asd" test) generated 1 warning (1 duplicate)
    Finished dev [unoptimized + debuginfo] target(s) in 0.07s

Meta

Rust version (rustc -Vv):

rustc 1.58.0-nightly (ff0e14829 2021-10-31)
binary: rustc
commit-hash: ff0e14829e1806ca0d4226595f7fdf3e8658758f
commit-date: 2021-10-31
host: x86_64-unknown-linux-gnu
release: 1.58.0-nightly
LLVM version: 13.0.0

@rustbot label +I-suggestion-causes-error