There is one occurrence of this in glib, which we currently miss.
See bug 585717.
$(srcdir)/$(GETTEXT_PACKAGE).pot: $(POTFILES)
$(XGETTEXT) --default-domain=$(GETTEXT_PACKAGE) --directory=$(top_srcdir) \
--add-comments --keyword=_ --keyword=N_ \
+ --keyword=C_:1c,2 \
+ --keyword=NC_:1c,2 \
+ --keyword=g_dngettext:2,3 \
+ --flag=N_:1:pass-c-format \
+ --flag=C_:2:pass-c-format \
+ --flag=NC_:2:pass-c-format \
+ --flag=g_dngettext:2:pass-c-format \
--flag=g_strdup_printf:1:c-format \
--flag=g_string_printf:2:c-format \
--flag=g_string_append_printf:2:c-format \