"x86_64-w64-mingw32-gcc -o conftest.exe -IC:/Ruby22-x64/include/ruby-2.2.0/x64-mingw32 -IC:/Ruby22-x64/include/ruby-2.2.0/ruby/backward -IC:/Ruby22-x64/include/ruby-2.2.0 -I. -DFD_SETSIZE=2048 -D_WIN32_WINNT=0x0501 -D__MINGW_USE_VC2005_COMPAT -D_FILE_OFFSET_BITS=64   -O3 -fno-omit-frame-pointer -fno-fast-math -g -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wimplicit-function-declaration -Wdeprecated-declarations -Wno-packed-bitfield-compat conftest.c  -L. -LC:/Ruby22-x64/lib -L.      -lx64-msvcrt-ruby220  -lshell32 -lws2_32 -liphlpapi -limagehlp -lshlwapi  "
checked program was:
/* begin */
1: #include "ruby.h"
2: 
3: #include <winsock2.h>
4: #include <windows.h>
5: int main(int argc, char **argv)
6: {
7:   return 0;
8: }
/* end */

"x86_64-w64-mingw32-gcc -IC:/Ruby22-x64/include/ruby-2.2.0/x64-mingw32 -IC:/Ruby22-x64/include/ruby-2.2.0/ruby/backward -IC:/Ruby22-x64/include/ruby-2.2.0 -I. -DFD_SETSIZE=2048 -D_WIN32_WINNT=0x0501 -D__MINGW_USE_VC2005_COMPAT -D_FILE_OFFSET_BITS=64   -O3 -fno-omit-frame-pointer -fno-fast-math -g -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wimplicit-function-declaration -Wdeprecated-declarations -Wno-packed-bitfield-compat   -c conftest.c"
checked program was:
/* begin */
1: #include "ruby.h"
2: 
3: #include <winsock2.h>
4: #include <windows.h>
5: /*top*/
6: #ifndef _WIN32
7: # error
8: |:/ === _WIN32 undefined === /:|
9: #endif
/* end */