Tvheadend

CC              src/idnode.o
src/idnode.c: In function ‘idnode_slist_set’:
src/idnode.c:1551:13: error: argument 1 null where non-null expected [-Werror=nonnull]
         if (strcmp(s, o->id))
             ^~~~~~~~~~~~~~~~
In file included from src/idnode.c:24:0:
/usr/include/string.h:136:12: note: in a call to function ‘strcmp’ declared here
 extern int strcmp (const char *__s1, const char *__s2)
            ^~~~~~
cc1: all warnings being treated as errors
Makefile:630: recipe for target '/root/tvheadend-4.2.1/build.linux/src/idnode.o' failed
make: *** [/root/tvheadend-4.2.1/build.linux/src/idnode.o] Error 1

1548       HTSMSG_FOREACH(f, vals) {
1549         if ((s = htsmsg_field_get_str(f)) != NULL)
1550           continue;
1551         if (strcmp(s, o->id))
1552           continue;
1553         if (*ip == 0) changed = 1;
1554         break;
1555       }

I'm not sure what's going on, but s is always NULL at the time of strcmp. I can't build 4.3 for the same reason.