Reported in #eventmachine by [PQ3]RailWolf?.
g++ -I. -I. -I/usr/lib/ruby/1.8/i386-cygwin -I/home/em/eventmachine/ext -DHAVE_OPENSSL_SSL_H -DHAVE_OPENSSL_ERR_H -DOS_UNIX
-DBUILD_FOR_RUBY -DWITH_SSL -g -O2 -c em.cpp
em.cpp: In function `sockaddr* name2address(const char*, int, int*, int*)':
em.cpp:1178: error: aggregate `sockaddr_in6 in6' has incomplete type and cannot be defined
em.cpp:1197: error: `AF_INET6' undeclared (first use this function)
em.cpp:1197: error: (Each undeclared identifier is reported only once for each function it appears in.)
make: *** [em.o] Error 1
setup.rb:655:in `command': system("make") failed (RuntimeError)
from setup.rb:664:in `make'
from setup.rb:1258:in `setup_dir_ext'
from setup.rb:1532:in `__send__'
from setup.rb:1532:in `traverse'
from setup.rb:1549:in `dive_into'
from setup.rb:1530:in `traverse'
from setup.rb:1524:in `exec_task_traverse'
from setup.rb:1519:in `each'
from setup.rb:1519:in `exec_task_traverse'
from setup.rb:1246:in `exec_setup'
from setup.rb:996:in `exec_setup'
from setup.rb:813:in `invoke'
from setup.rb:773:in `invoke'
from setup.rb:1578
Requires fix in extconf.
He was trying to use cygwin due to the lack of #popen on win32 native.
