E0529 wrong infinite suggestion to add `as_deref`

Code

use std::io::ErrorKind;
use std::borrow::Cow;

fn f(x: Result<i32, Vec<ErrorKind>>) -> bool {
    matches!(x, Err([ErrorKind::NotFound]))
}

Current output

error[E0529]: expected an array or slice, found `Vec<ErrorKind>`
 --> src/lib.rs:5:21
  |
5 |     matches!(x, Err([ErrorKind::NotFound]))
  |                     ^^^^^^^^^^^^^^^^^^^^^ pattern cannot match with input type `Vec<ErrorKind>`
  |
help: consider using `as_deref` here
  |
5 |     matches!(x.as_deref(), Err([ErrorKind::NotFound]))
  |               +++++++++++

Desired output

no suggestion to use as_deref

Rationale and extra context

1. as_deref doesn't change the meaning of the code.
2. When applied, rustc will suggest to apply it again, which is absurd and confusing.

Other cases

matches!(x.as_deref().as_deref().as_deref(), Err([ErrorKind::NotFound]))

will suggest

help: consider using `as_deref` here
  |
5 |     matches!(x.as_deref().as_deref().as_deref().as_deref(), Err([ErrorKind::NotFound]))
  |                                                +++++++++++

Rust Version

rustc 1.81.0 (eeb90cda1 2024-09-04)
binary: rustc
commit-hash: eeb90cda1969383f56a2637cbd3037bdf598841c
commit-date: 2024-09-04
host: x86_64-unknown-linux-gnu
release: 1.81.0
LLVM version: 18.1.7

Anything else?

No response

Start with the supplied Rust reproducer and investigate the rustc E0529 diagnostic path that proposes as_deref; the issue names no source file or test. Done means the compiler no longer emits that suggestion for the shown case or repeated as_deref calls, verified by rerunning the reproducer.