`cast_possible_truncation` false negative when casting `u32` → `usize`

[xtqqczze]

Summary

clippy::cast_possible_truncation fails to warn when casting u32 to usize even though truncation is possible on platforms where usize is narrower than 32 bits (e.g., 16-bit pointer-width targets).

Lint Name

cast_possible_truncation

Reproducer

I tried this code:

#[deny(clippy::cast_possible_truncation)]
pub fn as_usize(x: u32) -> usize {
    x as usize
}

I expected to see this happen:

error: casting `u32` to `usize` may truncate the value on targets with 16-bit wide pointers

Instead, this happened:

lint did not fire

Version