output of rustc +enzyme --version --verbose:

rustc 1.84.0-nightly (1203575 2024-10-30)
binary: rustc
commit-hash: 1203575
commit-date: 2024-10-30
host: x86_64-unknown-linux-gnu
release: 1.84.0-nightly
LLVM version: 19.1.1

an example:

#![feature(autodiff)]
use std::autodiff::autodiff;

fn main() {
    #[autodiff(d_inner, Forward, Dual, DualOnly)]
    fn inner(x: f32) -> f32 {
        x * x
    }
}

build results in the error message (with the first line with the path manually removed)

error: autodiff must be applied to function
 --> src/main.rs:6:5
  |
6 | /     fn inner(x: f32) -> f32 {
7 | |         x * x
8 | |     }
  | |_____^

error: could not compile `enzyme-test` (bin "enzyme-test") due to 1 previous error