See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=271485:
> Clang 16 has a new error about incompatible function types, which shows
> up when building devel/libgee:
>
> hashmap.c:4089:23: error: incompatible function pointer types assigning to 'gboolean (*)(GeeMapIterator *)' (aka 'int (*)(struct _GeeMapIterator *)') from 'gboolean (GeeHashMapNodeIterator *)' (aka 'int (struct _GeeHashMapNodeIterator *)') [-Wincompatible-function-pointer-types]
> iface->get_read_only = gee_hash_map_map_iterator_real_get_read_only;
> ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Since the error occurs in vala-generated code, it does not make sense to
> patch the .c file. Suppress the warning instead.
