While it's probably a good idea for us to stop using `AM_GLIB_GNU_GETTEXT` anyway, it [hasn't been removed from GLib](https://gitlab.gnome.org/GNOME/glib/blob/master/m4macros/glib-gettext.m4#L46...). And it [seems like they agree they should keep the public M4 macros](https://gitlab.gnome.org/GNOME/glib/commit/b3efef5b6ff2515551f300aed7ca16bd7...): _"We continue to install autoconf macros for autotools-using projects which depend on GLib; they are stable API."_
@BZHDeveloper in what setup do you miss the macro? It looks like either a bug on GLib's part, or on whatever way you have for obtaining such a bleeding edge version.