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

Replace proc-macro-error-2 dependency in leptos_macro — crate is now archived

Summary

leptos_macro depends on proc-macro-error-2, which was archived on June 7, 2026 and is now read-only and unmaintained. (The owner of proc-macro-error-2 created proc-macro-error-3)

There's an open issue on proc-macro-error-2 repository /GnomedDev/proc-macro-error-2/issues/17.

Impact

• cargo audit / cargo deny flags RUSTSEC-2026-0173 in any Leptos-based project
• The crate will break on a future Rust release
• No fixes, patches, or updates will be forthcoming from the upstream