minmax.m4

来自「linux下常用的网络工具的代码」· M4 代码 · 共 42 行

# minmax.m4 serial 2
dnl Copyright (C) 2005 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_PREREQ(2.52)

AC_DEFUN([gl_MINMAX],
[
  AC_REQUIRE([gl_PREREQ_MINMAX])
])

# Prerequisites of lib/minmax.h.
AC_DEFUN([gl_PREREQ_MINMAX],
[
  gl_MINMAX_IN_HEADER([limits.h])
  gl_MINMAX_IN_HEADER([sys/param.h])
])

dnl gl_MINMAX_IN_HEADER(HEADER)
dnl The parameter has to be a literal header name; it cannot be macro,
dnl nor a shell variable. (Because autoheader collects only AC_DEFINE
dnl invocations with a literal macro name.)
AC_DEFUN([gl_MINMAX_IN_HEADER],
[
  m4_pushdef([header], AS_TR_SH([$1]))
  m4_pushdef([HEADER], AS_TR_CPP([$1]))
  AC_CACHE_CHECK([whether <$1> defines MIN and MAX],
    [gl_cv_minmax_in_]header,
    [AC_TRY_COMPILE([#include <$1>
int x = MIN (42, 17);], [],
       [gl_cv_minmax_in_]header[=yes],
       [gl_cv_minmax_in_]header[=no])])
  if test $gl_cv_minmax_in_[]header = yes; then
    AC_DEFINE([HAVE_MINMAX_IN_]HEADER, 1,
      [Define to 1 if <$1> defines the MIN and MAX macros.])
  fi
  m4_popdef([HEADER])
  m4_popdef([header])
])