Re: [Qemu-devel] bug with io/channel-socket.c - variable-sized object may not be initialized

[Programmingkid]

On Jan 15, 2016, at 6:56 PM, Eric Blake wrote:

> On 01/13/2016 02:19 PM, Programmingkid wrote:
>> This code causes an error to occur during compiling: 
>> 
>> char control[CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS)] = { 0 };
>> 
>> It is located at line 496 in io/channel-socket.c. 
>> 
>> Here is the full error message:
>> io/channel-socket.c: In function 'qio_channel_socket_writev':
>> io/channel-socket.c:496:18: error: variable-sized object may not be 
>> initialized
>>     char control[CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS)] = { 0 };
>> 
>> This is from gcc 4.9 running on Mac OS 10.6.8. 
> 
> Uggh. That sounds like a bug in the Mac OS headers, for making
> CMSG_SPACE() not be a compile-time constant.  We do NOT want to be using
> variable-sized objects here, so we need a compile-time constant for the
> array size, even if we have to work around your platform's borked headers.
> Can you capture what that line expands to after pre-processing, to see
> if my guess is right?

It expands to 76.