`dangerous_implicit_autorefs` lint suggestion triggers `clippy::needless_borrow`

[wyfo]

Description

(transfered from rust-lang/rust#140720)

Let's take the following example:

unsafe fn slice_ptr_len_because_of_msrv<T>(slice: *[T]) -> usize {
    unsafe { (*slice).len() }
}

on current nightly, it triggers:

warning: implicit autoref creates a reference to the dereference of a raw pointer
 --> src/main.rs:2:14
  |
3 |     unsafe { (*slice).len() }
  |              ^^^^^^^^^^^^^^
  |
  = note: creating a reference requires the pointer target to be valid and imposes aliasing requirements
  = note: `#[warn(dangerous_implicit_autorefs)]` on by default
help: try using a raw pointer method instead; or if this reference is intentional, make it explicit
  |
3 |     unsafe { (&(*slice)).len() }
  |              ++        +

If the suggestion is applied, then clippy complains:

warning: this expression borrows a value the compiler would automatically borrow
 --> src/main.rs:2:14
  |
2 |     unsafe { (&(*slice)).len() }
  |              ^^^^^^^^^^^ help: change this to: `(*slice)`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow
  = note: `#[warn(clippy::needless_borrow)]` on by default

Curiously enough, (*slice)[..].len() also triggers dangerous_implicit_autorefs, but the suggested (&(*slice))[..].len() doesn't trigger clippy::needless_borrow.

Version

rustc 1.88.0-nightly (2e6882ac5 2025-05-05)
binary: rustc
commit-hash: 2e6882ac5be27a73293d6f7ae56397fdf32848de
commit-date: 2025-05-05
host: aarch64-apple-darwin
release: 1.88.0-nightly
LLVM version: 20.1.4

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