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emacs/m4/clock_time.m4
2024-05-11 18:46:26 -07:00

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# clock_time.m4
# serial 14
dnl Copyright (C) 2002-2006, 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.
# Check for clock_getres, clock_gettime and clock_settime,
# and set CLOCK_TIME_LIB.
# For a program named, say foo, you should add a line like the following
# in the corresponding Makefile.am file:
# foo_LDADD = $(LDADD) $(CLOCK_TIME_LIB)
AC_DEFUN([gl_CLOCK_TIME],
[
AC_REQUIRE([AC_CANONICAL_HOST])
dnl Persuade glibc and Solaris <time.h> to declare these functions.
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
# On mingw, these functions are defined in the libwinpthread library,
# which is better avoided. In fact, the clock_gettime function is buggy
# in 32-bit mingw, when -D__MINGW_USE_VC2005_COMPAT is used (which Gnulib's
# year2038 module does): It leaves the upper 32 bits of the tv_sec field
# of the result uninitialized.
# Solaris 2.5.1 needs -lposix4 to get the clock_gettime function.
# Solaris 7 prefers the library name -lrt to the obsolescent name -lposix4.
# Save and restore LIBS so e.g., -lrt, isn't added to it. Otherwise, *all*
# programs in the package would end up linked with that potentially-shared
# library, inducing unnecessary run-time overhead.
CLOCK_TIME_LIB=
AC_SUBST([CLOCK_TIME_LIB])
case "$host_os" in
mingw* | windows*)
ac_cv_func_clock_getres=no
ac_cv_func_clock_gettime=no
ac_cv_func_clock_settime=no
;;
*)
gl_saved_libs=$LIBS
AC_SEARCH_LIBS([clock_gettime], [rt posix4],
[test "$ac_cv_search_clock_gettime" = "none required" ||
CLOCK_TIME_LIB=$ac_cv_search_clock_gettime])
AC_CHECK_FUNCS([clock_getres clock_gettime clock_settime])
LIBS=$gl_saved_libs
;;
esac
# For backward compatibility.
LIB_CLOCK_GETTIME="$CLOCK_TIME_LIB"
AC_SUBST([LIB_CLOCK_GETTIME])
])