NanoBSD: CURRENT unable to compile 13-STABLE : error: a function definition without a prototype is deprecated ... in C

Running recent CURRENT as host (FreeBSD 14.0-CURRENT #23 main-n261147-b8bb73ab724b: Sun Feb 26
17:39:38 CET 2023 amd64), and nanoBSD (recent 13-STABLE, git stable/13).

Building an appliance based on 13-STABLE sources, a customized kernel via nanoBSD, since a
couple of weeks for now building the sources fails in kernel sources:

[...]
--- modules-all ---
--- all_subdir_an ---
/pool/home/ohartmann/Projects/router/router/apu2c4/src/sys/dev/an/if_an_pci.c:143:1: error: a
function definition without a prototype is deprecated in all versions of C and is not
supported in C2x [-Werror,-Wdeprecated-non-prototype]
[..]

Disabling all wireless options in the kernel config starts dropping errors of a similar kind
on other kernel places.

Compiling on FBSD 13-STABLE seems to be all right.

Can this be fixed. please? What causes the error and how can this be resolved if the subtree
of FreeBSD's sources is a submodule?

Thanks in advance,

Oliver



-- 
O. Hartmann