It looks initialized to me. What gcc version is that?
gcc version 7.2.0, running on latest Arch Linux. I'm compiling with -Werror, that's how I noticed. Complete error:
In file included from ../../../../wine-git/include/winsock2.h:47:0, from ../../../../wine-git/dlls/ws2_32/tests/sock.c:25: ../../../../wine-git/dlls/ws2_32/tests/sock.c: In function
‘SelectReadThread’:
../../../../wine-git/include/winsock.h:480:37: error:
‘readfds.fd_array[__i]’ may be used uninitialized in this function [- Werror=maybe-uninitialized]
if (((cast*)(set))->fd_array[__i]==(fd)) \
Regards, Fabian Maurer