[False Positive] About removing a into_iter() from an ops::Range

[leonardo-m]

Summary

If I have this little Rust program:

#![warn(clippy::all)]
use std::ops::Range;

const fn signature(mut n: u32) -> u32 {
    let mut result = 0;
    loop {
        result += 1 << ((n % 10) * 4);
        n /= 10;
        if n == 0 { return result; }
    }
}

fn main() {
    const R: Range<u32> = 2 .. 7; // Input.
    let g = |n, sn| R.into_iter().all(|m| signature(n * m) == sn);
    let res = (1 .. u32::MAX).find(|&n| g(n, signature(n)));
    assert_eq!(res, Some(142_857));
}

Clippy gives me this warning:

warning: useless conversion to the same type: `std::ops::Range<u32>`
  --> src/main.rs:15:21
   |
15 |     let g = |n, sn| R.into_iter().all(|m| signature(n * m) == sn);
   |                     ^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `R`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#useless_conversion
note: the lint level is defined here
  --> src/main.rs:1:9
   |
1  | #![warn(clippy::all)]
   |         ^^^^^^^^^^^
   = note: `#[warn(clippy::useless_conversion)]` implied by `#[warn(clippy::all)]`

But if I remove ".into_iter()" from the Rust program, the rustc compiler (1.88.0-nightly 2025-04-19) gives me:

warning: taking a mutable reference to a `const` item
  --> ...\bug1.rs:15:21
   |
15 |     let g = |n, sn| R.all(|m| signature(n * m) == sn);
   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: each usage of a `const` item creates a new temporary
   = note: the mutable reference will refer to this temporary, not the original `const` item
note: mutable reference created due to call to this method
  --> /rustc/077cedc2afa8ac0b727b7a6cbe012940ba228deb\library\core\src\iter\traits\iterator.rs:2719:5
note: `const` item defined here
  --> ...\bug1.rs:14:5
   |
14 |     const R: Range<u32> = 2 .. 7; // Input.
   |     ^^^^^^^^^^^^^^^^^^^
   = note: `#[warn(const_item_mutation)]` on by default

Lint Name

No response

Reproducer

I tried this code:

<code>

I saw this happen:

<output>

I expected to see this happen:

Version

Additional Labels

No response