Is there any update on this, i.e., what would be the steps required to get the proposed patch merged?

As we (Proxmox) would also like to use gettext in rust based projects, and while we can write our own scanner, or try applying the proposed patch to a downstream build, we'd rather see the already existing effort getting upstreamed.

I would like to work on that feature.

I looked around the code a bit and basically we need "format-rust.c" for msgfmt and "x-rust.c" for xgettext, right?

Here are Rust i18n libraries compatible with gettext:

• gettext: emulates gettext. It provides gettext, ngettext, pgettext and npgettext methods on a Catalog object with the same API as the corresponding gettext functions. It doesn't support Rust string formatting.
• gettext-rs: uses gettext. It provides gettext, ngettext, pgettext, npgettext, dcgettext, dcngettext, dgettext, dngettext methods with the same API as the corresponding gettext functions. It provides macros with the same names and the macro invocation operator '!' that allow Rust string formatting while keeping a regular function API. It doesn't support all of Rust string format yet.
• tr: uses either of the two previous libraries. It provides a single tr! macro that allows Rust string formatting but has its own API to support the same features as gettext, ngettext, pgettext, npgettext. It doesn't support all of Rust string format yet. It provides its own extractor called xtr.

An extractor using keywords for gettext functions names and macro names should work with the two first libraries. A parser for Rust string format should work with all three libraries.

GNOME Rust apps usually use the gettext-rs library.

Also note this discussion about supporting Rust in GNOME i18n.

https://gitlab.gnome.org/GNOME/fractal/-/issues/874