[arithmetic_side_effects] Division by NonZeroU* cannot panic

[guilliamxavier]

Summary

Division (/ and %, i.e. div() and rem()) implemented for the following pairs of types:

• (u8, core::num::NonZeroU8)
• (u16, core::num::NonZeroU16)
• (u32, core::num::NonZeroU32)
• (u64, core::num::NonZeroU64)
• (u128, core::num::NonZeroU128)
• (usize, core::num::NonZeroUsize)

never panics (because the (x, 0) and (MIN, -1) cases are impossible), but the arithmetic_side_effects lint currently flags them.

(Note: I recognize that this is a very specific case and don't know if it can be fixed)

Lint Name

arithmetic_side_effects

Reproducer

I tried this code:

#![warn(clippy::arithmetic_side_effects)]

use std::num::NonZeroUsize;

fn example_div(unsigned: usize, nonzero_unsigned: NonZeroUsize) -> usize {
    unsigned / nonzero_unsigned
}

fn example_rem(unsigned: usize, nonzero_unsigned: NonZeroUsize) -> usize {
    unsigned % nonzero_unsigned
}

fn main() {
    let (unsigned, nonzero_unsigned) = (0, NonZeroUsize::new(1).unwrap());

    println!("{unsigned} / {nonzero_unsigned} is {}", example_div(unsigned, nonzero_unsigned));
    println!("{unsigned} % {nonzero_unsigned} is {}", example_rem(unsigned, nonzero_unsigned));
}

(note: compiles and runs fine, output:

0 / 1 is Ok(0)
0 % 1 is Ok(0)

)

I saw this happen:

warning: arithmetic operation that can potentially result in unexpected side-effects
 --> src/main.rs:6:5
  |
6 |     unsigned / nonzero_unsigned
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arithmetic_side_effects
note: the lint level is defined here
 --> src/main.rs:1:9
  |
1 | #![warn(clippy::arithmetic_side_effects)]
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: arithmetic operation that can potentially result in unexpected side-effects
  --> src/main.rs:10:5
   |
10 |     unsigned % nonzero_unsigned
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arithmetic_side_effects

I expected to see this happen:

No warning

Version

Clippy 0.1.73 (2023-08-23 249595b) on the Rust Playground,
which I guess corresponds to rustc 1.74.0-nightly (2023-08-23 249595b7523fc07a99c1)

Additional Labels

No response

[c410-f3r]

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