RUSTSEC-2026-0173: proc-macro-error2 is unmaintained

> proc-macro-error2 is unmaintained

| Details | |
| ------------------- | ---------------------------------------------- |
| Status | unmaintained |
| Package | `proc-macro-error2` |
| Version | `2.0.1` |
| URL | [https://github.com/GnomedDev/proc-macro-error-2/issues/17](https://github.com/GnomedDev/proc-macro-error-2/issues/17) |
| Date | 2026-06-07 |

The author of `proc-macro-error2` has [confirmed](https://github.com/GnomedDev/proc-macro-error-2/issues/17#issuecomment-4643215473) that the crate is no longer maintained and recommends that users migrate away from it.

`proc-macro-error2` was originally created as a maintained fork of [`proc-macro-error`](https://crates.io/crates/proc-macro-error) (see [RUSTSEC-2024-0370](https://rustsec.org/advisories/RUSTSEC-2024-0370)). Both the original crate and this fork are now unmaintained.

## Possible Alternative(s)

- [manyhow](https://crates.io/crates/manyhow)
- [proc-macro2-diagnostics](https://github.com/SergioBenitez/proc-macro2-diagnostics)

See [advisory page](https://rustsec.org/advisories/RUSTSEC-2026-0173.html) for additional details.

Start by locating proc-macro-error2 in the repository's dependency manifests and searching for its usage. Compare the affected APIs with manyhow or proc-macro2-diagnostics, then run the relevant Rust checks and tests. Done means the unmaintained dependency is removed and the project still builds and passes its existing tests.

Written by the indexing model from the issue text.