Re: [Qemu-devel] [PATCH 04/12] slirp: add in6_multicast() and use it instead of IN6_IS_ADDR_MULTICAST()

[Richard Henderson]

On 01/08/2018 09:28 AM, Philippe Mathieu-Daudé wrote:
> Host: Mac OS 10.12.5
> Compiler: Apple LLVM version 8.1.0 (clang-802.0.42)
> 
>   slirp/ip6_icmp.c:79:32: warning: taking address of packed member 'ip_src' 
> of class or
>         structure 'ip6' may result in an unaligned pointer value
>         [-Waddress-of-packed-member]
>       if (IN6_IS_ADDR_MULTICAST(&ip->ip_src) ||
>                                  ^~~~~~~~~~
>   /usr/include/netinet6/in6.h:299:36: note: expanded from macro 
> 'IN6_IS_ADDR_MULTICAST'
>   #define IN6_IS_ADDR_MULTICAST(a)        ((a)->s6_addr[0] == 0xff)

The fact that you replace a macro with a function of exactly the same code in
order to avoid a diagnostic sure looks like a compiler bug to me.


r~