if_flags is in-kernel, so definately this should become unsigned.
But what about if_msghdr.ifm_flags? That is exposed to userland, but
I'd support moving it to unsigned because the route socket is a less
standardized interface.
struct ipoption is a little less clear. It is exposed to userland; one
example that uses this is libc/rpc/svc_tcp.c. In that instance it is
cast to u_char as expected. I wonder whether there is userland code which
might be affected by this, however even if there was I would support the
trend towards making this unsigned.
> the new clang complains when variables might unintentionally switch from
> a positive to a negative number. This happens on the MULTICAST flag
> which sets the uppermost bit.
>
> ../../../../net/if.h:#define IFF_MULTICAST 0x8000 /* supports
> multicast */
>
> Thus if_flags = IFF_MULTICAST would switch from the positive 0x8000 to
> something negative. The same happens in the ipoption struct.
>
> What should we do? Disable the warning or simply switch the variables
> to being unsigned? Keep note that this diff is untested, even though I
> wouldn't expect anything bad to happen by that change...
>
> Patrick
>
> diff --git a/sys/net/if_var.h b/sys/net/if_var.h
> index 702fc5539c1..e254744dac8 100644
> --- a/sys/net/if_var.h
> +++ b/sys/net/if_var.h
> @@ -126,7 +126,7 @@ struct ifnet { /* and the
> entries */
> #define if_carpdev if_carp_ptr.carp_d
> unsigned int if_index; /* numeric abbreviation for this if */
> short if_timer; /* time 'til if_watchdog called */
> - short if_flags; /* up/down, broadcast, etc. */
> + unsigned short if_flags; /* up/down, broadcast, etc. */
> int if_xflags; /* extra softnet flags */
> struct if_data if_data; /* stats and other data about if */
> u_int32_t if_hardmtu; /* maximum MTU device supports */
> diff --git a/sys/netinet/ip_var.h b/sys/netinet/ip_var.h
> index 7d1663dc8b3..cabb364cdc4 100644
> --- a/sys/netinet/ip_var.h
> +++ b/sys/netinet/ip_var.h
> @@ -91,7 +91,7 @@ struct ipstat {
>
> struct ipoption {
> struct in_addr ipopt_dst; /* first-hop dst if source routed */
> - int8_t ipopt_list[MAX_IPOPTLEN]; /* options proper */
> + u_int8_t ipopt_list[MAX_IPOPTLEN]; /* options proper */
> };
>
> #ifdef _KERNEL
>
