AC_DEFUN([TORRENT_MINCORE_SIGNEDNESS], [
 
  AC_LANG_PUSH(C++)
  AC_MSG_CHECKING(signedness of mincore parameter)
 
  AC_COMPILE_IFELSE(
    [[#include <sys/types.h>
      #include <sys/mman.h>
      void f() { mincore((void*)0, 0, (unsigned char*)0); }
    ]],
    [
      AC_DEFINE(USE_MINCORE_UNSIGNED, 1, use unsigned char* in mincore)
      AC_MSG_RESULT(unsigned)
    ],
    [
      AC_COMPILE_IFELSE(
        [[#include <sys/types.h>
          #include <sys/mman.h>
          void f() { mincore((void*)0, 0, (char*)0); }
        ]],
        [
          AC_DEFINE(USE_MINCORE_UNSIGNED, 0, use char* in mincore)
          AC_MSG_RESULT(signed)
        ],
        [
          AC_MSG_ERROR([mincore signedness test failed])
      ])
  ])
 
  AC_LANG_POP(C++)
])