emacs/m4/gettime.m4

# gettime.m4
# serial 15
dnl Copyright (C) 2002, 2004-2006, 2009-2024 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_DEFUN([gl_GETTIME],
[
  dnl Prerequisites of lib/gettime.c.
  AC_REQUIRE([gl_CLOCK_TIME])
  AC_REQUIRE([gl_TIMESPEC])

  AC_REQUIRE([gl_CHECK_FUNC_TIMESPEC_GET])
  if test $gl_cv_func_timespec_get = yes; then
    AC_DEFINE([HAVE_TIMESPEC_GET], [1],
      [Define if you have the timespec_get function.])
  fi
])

dnl Tests whether the function timespec_get exists.
dnl Sets gl_cv_func_timespec_get and gl_cv_onwards_func_timespec_get.
AC_DEFUN([gl_CHECK_FUNC_TIMESPEC_GET],
[
  AC_REQUIRE([AC_CANONICAL_HOST])

  dnl Persuade OpenBSD <time.h> to declare timespec_get().
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  dnl We can't use AC_CHECK_FUNC here, because timespec_get() is defined as a
  dnl static inline function in <time.h> on MSVC 14.
  dnl But at the same time, we need to notice a missing declaration, like
  dnl gl_CHECK_FUNCS_ANDROID does.
  AC_CHECK_DECL([timespec_get], , , [[#include <time.h>]])
  AC_CACHE_CHECK([for timespec_get], [gl_cv_onwards_func_timespec_get],
    [if test $ac_cv_have_decl_timespec_get = yes; then
       AC_LINK_IFELSE(
         [AC_LANG_PROGRAM(
            [[#include <time.h>
              struct timespec ts;
            ]],
            [[return timespec_get (&ts, 0);]])
         ],
         [gl_cv_onwards_func_timespec_get=yes],
         [gl_cv_onwards_func_timespec_get=no])
     else
       gl_cv_onwards_func_timespec_get=no
     fi
     case "$host_os" in
       linux*-android*)
         if test $gl_cv_onwards_func_timespec_get = no; then
           gl_cv_onwards_func_timespec_get='future OS version'
         fi
         ;;
     esac
    ])
  case "$gl_cv_onwards_func_timespec_get" in
    future*) gl_cv_func_timespec_get=no ;;
    *)       gl_cv_func_timespec_get=$gl_cv_onwards_func_timespec_get ;;
  esac
])

AC_DEFUN([gl_GETTIME_RES],
[
  dnl Prerequisites of lib/gettime-res.c.
  AC_REQUIRE([gl_CLOCK_TIME])
  AC_REQUIRE([gl_TIMESPEC])
  gl_CHECK_FUNCS_ANDROID([timespec_getres], [[#include <time.h>]])
])