cast_abs_to_unsigned

[SwishSwushPow]

Summary

The lint cast_abs_to_unsigned is showing a warning even when the variable is cast to usize. The recommended code change does not produce working code and in the end leads to a more convoluted solution. Maybe the lint should not be triggered by code that is casting to usize.

Lint Name

cast_abs_to_unsigned

Reproducer

I tried this code:

fn main() {
    let a: i32 = -3;
    let _: usize = a.abs() as usize; // this produces the `cast_abs_to_unsigned` warning

    // let _: usize = a.unsigned_abs(); // fails with "mismatched types, expected `usize`, found `u32`"
    // let _: usize = a.unsigned_abs().try_into().unwrap(); // this is then recommended
}

I saw this happen:

warning: casting the result of `i32::abs()` to usize
 --> src/main.rs:3:20
  |
3 |     let _: usize = a.abs() as usize;
  |                    ^^^^^^^^^^^^^^^^ help: replace with: `a.unsigned_abs()`
  |
  = note: `#[warn(clippy::cast_abs_to_unsigned)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#cast_abs_to_unsigned

I expected to see this happen: I suppose the lint does not apply to such a line of code.

Version

rustc 1.61.0 (fe5b13d68 2022-05-18)

Additional Labels

No response