RUSTSEC-2026-0173 `proc-macro-2` is now unmaintained

[chainyo]

Description

Hi, the repo proc-macro-2 recently went into an unmaintained state according to RUSTSEC-2026-0173

Do you guys would accept PRs to move away and use a replacement for this library?

Actual Behavior

I'm getting this error in my CI from this morning

error[unmaintained]: proc-macro-error2 is unmaintained
    ┌─ /github/workspace/Cargo.lock:201:1
    │
201 │ proc-macro-error2 2.0.1 registry+https://github.com/rust-lang/crates.io-index
    │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ unmaintained advisory detected
    │
    ├ ID: RUSTSEC-2026-0173
    ├ Advisory: https://rustsec.org/advisories/RUSTSEC-2026-0173
    ├ 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has [confirmed](https://github.com/GnomedDev/proc-macro-error-2/issues/17#issuecomment-4643215473) that the crate is no longer maintained and recommends that users migrate away from it.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)
    ├ Announcement: https://github.com/GnomedDev/proc-macro-error-2/issues/17
    ├ Solution: No safe upgrade is available!
    ├ proc-macro-error2 v2.0.1
      └── sea-bae v0.2.1
          └── sea-orm-macros v1.1.20
              └── sea-orm v1.1.20
                  ├── app-db v0.1.0
                  │   ├── backend v0.1.0
                  │   └── model-gateway v0.1.0
                  └── sea-orm-migration v1.1.20
                      └── app-migration v0.1.0
                          ├── (dev) app-db v0.1.0 (*)
                          └── (dev) backend v0.1.0 (*)

Versions

v0.2.1

Additional Information

I'm open to contribute to help on the migration

[gamma0987]

The RUSTSEC advisory lists manyhow and proc-macro2-diagnostics as alternatives, but both require rewriting how errors are reported in your proc macros. proc-macro-error3 is a maintained fork and drop-in replacement - same API, no code changes beyond the dependency rename, so the switch is minimal and low-risk.

I maintain proc-macro-error3 and use it in my projects, mainly https://github.com/gungraun/gungraun. Would you be open to this switch? I'm happy to submit a PR if that would help.

[ggirol-rc]

I have done it in #3