Incorrect clippy::op_ref warning on `&s[0]`

[jsgf]

Given the code:

pub fn inrange<T: Ord>(s: &[T], n: &T) -> bool {
    s.last().map_or(false, |last| &s[0] <= n && n <= last)
}

Clippy warns:

 --> src/lib.rs:2:35
  |
2 |     s.last().map_or(false, |last| &s[0] <= n && n <= last)
  |                                   -----^^^^^
  |                                   |
  |                                   help: use the left value directly: `s[0]`
  |
  = note: `#[warn(clippy::op_ref)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#op_ref

However, this is incorrect, as n has reference type &T. Changing it to s[0] <= n fails to compile:

error[E0308]: mismatched types
 --> src/lib.rs:2:43
  |
2 |     s.last().map_or(false, |last| s[0] <= n && n <= last)
  |                                           ^ expected type parameter, found &T
  |
  = note: expected type `T`
             found type `&T`
  = help: type parameters must be constrained to match other types
  = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters

[hellow554]

The span is also too big?

[flip1995]

Duplicate of #2597

Than span is also too big?

The span is fine. Usually the span of the suggestion == span of error message (especially in Clippy), this is then displayed with just ^^^. In this case the span of the suggestion is shorter than the span of the error message, which is displayed with --- (for the sugg span) and ^^^ (continuation for the error span).