Rustdoc integer overflow when calculating negative fieldless enum value

[SabrinaJewson]

I tried this code:

pub enum E {
    A = -2,
    B,
}
const _: [(); 1] = [(); -(E::B as i8) as usize];

I expected to see this happen: E::B is documented as taking the value -1.

Instead, this happened:

Meta

rustc --version --verbose:

rustc 1.89.0 (29483883e 2025-08-04)
binary: rustc
commit-hash: 29483883eed69d5fb4db01964cdf2af4d86e9cb2
commit-date: 2025-08-04
host: x86_64-unknown-linux-gnu
release: 1.89.0
LLVM version: 20.1.7

Also happens on Nightly:

rustc 1.91.0-nightly (7d82b83ed 2025-08-06)
binary: rustc
commit-hash: 7d82b83ed57d188ab3f2441a765a6419685a88a3
commit-date: 2025-08-06
host: x86_64-unknown-linux-gnu
release: 1.91.0-nightly
LLVM version: 21.1.0