arithmetic_side_effects: can’t see through trivial constant items

[nagisa]

Summary

arithmetic_side_effects lint correctly considers operations such as (somevar: u64) / 2 as non-side-effectful. However as soon as 2 is extracted into a constant, the lint starts firing.

I don't think it is critical that we handle complex constant evaluation here, but it would be nice if it handled at least basic literals like that so that this lint didn't become a motivation to inline magic numbers into the code.

Lint Name

arithmetic_side_effects

Reproducer

I tried this code:

#![deny(clippy::arithmetic_side_effects)]
fn foo(input: u64) -> u64 {
    const A: u64 = 1;
    input / A
}

I saw this happen:

error: arithmetic operation that can potentially result in unexpected side-effects
 --> src/lib.rs:5:5
  |
5 |     input / A
  |     ^^^^^^^^^

Version

rustc nightly / 0.1.68 (2023-01-17 3984bc5) on the playground

Additional Labels

No response

[c410-f3r]

@rustbot claim

I will try to at least see if the current machinery can handle this use-case but no promises.