m4/ax_pthread.m4 - xz - Git at Google


            
            # ===========================================================================

            
            #        http://www.gnu.org/software/autoconf-archive/ax_pthread.html

            
            # ===========================================================================

            
            #

            
            # SYNOPSIS

            
            #

            
            #   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])

            
            #

            
            # DESCRIPTION

            
            #

            
            #   This macro figures out how to build C programs using POSIX threads. It

            
            #   sets the PTHREAD_LIBS output variable to the threads library and linker

            
            #   flags, and the PTHREAD_CFLAGS output variable to any special C compiler

            
            #   flags that are needed. (The user can also force certain compiler

            
            #   flags/libs to be tested by setting these environment variables.)

            
            #

            
            #   Also sets PTHREAD_CC to any special C compiler that is needed for

            
            #   multi-threaded programs (defaults to the value of CC otherwise). (This

            
            #   is necessary on AIX to use the special cc_r compiler alias.)

            
            #

            
            #   NOTE: You are assumed to not only compile your program with these flags,

            
            #   but also link it with them as well. e.g. you should link with

            
            #   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS

            
            #

            
            #   If you are only building threads programs, you may wish to use these

            
            #   variables in your default LIBS, CFLAGS, and CC:

            
            #

            
            #     LIBS="$PTHREAD_LIBS $LIBS"

            
            #     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

            
            #     CC="$PTHREAD_CC"

            
            #

            
            #   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant

            
            #   has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to that name

            
            #   (e.g. PTHREAD_CREATE_UNDETACHED on AIX).

            
            #

            
            #   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the

            
            #   PTHREAD_PRIO_INHERIT symbol is defined when compiling with

            
            #   PTHREAD_CFLAGS.

            
            #

            
            #   ACTION-IF-FOUND is a list of shell commands to run if a threads library

            
            #   is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it

            
            #   is not found. If ACTION-IF-FOUND is not specified, the default action

            
            #   will define HAVE_PTHREAD.

            
            #

            
            #   Please let the authors know if this macro fails on any platform, or if

            
            #   you have any other suggestions or comments. This macro was based on work

            
            #   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help

            
            #   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by

            
            #   Alejandro Forero Cuervo to the autoconf macro repository. We are also

            
            #   grateful for the helpful feedback of numerous users.

            
            #

            
            #   Updated for Autoconf 2.68 by Daniel Richard G.

            
            #

            
            # LICENSE

            
            #

            
            #   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>

            
            #   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>

            
            #

            
            #   This program is free software: you can redistribute it and/or modify it

            
            #   under the terms of the GNU General Public License as published by the

            
            #   Free Software Foundation, either version 3 of the License, or (at your

            
            #   option) any later version.

            
            #

            
            #   This program is distributed in the hope that it will be useful, but

            
            #   WITHOUT ANY WARRANTY; without even the implied warranty of

            
            #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General

            
            #   Public License for more details.

            
            #

            
            #   You should have received a copy of the GNU General Public License along

            
            #   with this program. If not, see <http://www.gnu.org/licenses/>.

            
            #

            
            #   As a special exception, the respective Autoconf Macro's copyright owner

            
            #   gives unlimited permission to copy, distribute and modify the configure

            
            #   scripts that are the output of Autoconf when processing the Macro. You

            
            #   need not follow the terms of the GNU General Public License when using

            
            #   or distributing such scripts, even though portions of the text of the

            
            #   Macro appear in them. The GNU General Public License (GPL) does govern

            
            #   all other use of the material that constitutes the Autoconf Macro.

            
            #

            
            #   This special exception to the GPL applies to versions of the Autoconf

            
            #   Macro released by the Autoconf Archive. When you make and distribute a

            
            #   modified version of the Autoconf Macro, you may extend this special

            
            #   exception to the GPL to apply to your modified version as well.


            #serial 18


            AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])

            
            AC_DEFUN([AX_PTHREAD], [

            
            AC_REQUIRE([AC_CANONICAL_HOST])

            
            AC_LANG_PUSH([C])

            
            ax_pthread_ok=no


            # We used to check for pthread.h first, but this fails if pthread.h

            
            # requires special compiler flags (e.g. on True64 or Sequent).

            
            # It gets checked for in the link test anyway.


            # First of all, check if the user has set any of the PTHREAD_LIBS,

            
            # etcetera environment variables, and if threads linking works using

            
            # them:

            
            if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then

            
                    save_CFLAGS="$CFLAGS"

            
                    CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

            
                    save_LIBS="$LIBS"

            
                    LIBS="$PTHREAD_LIBS $LIBS"

            
                    AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])

            
                    AC_TRY_LINK_FUNC(pthread_join, ax_pthread_ok=yes)

            
                    AC_MSG_RESULT($ax_pthread_ok)

            
                    if test x"$ax_pthread_ok" = xno; then

            
                            PTHREAD_LIBS=""

            
                            PTHREAD_CFLAGS=""

            
                    fi

            
                    LIBS="$save_LIBS"

            
                    CFLAGS="$save_CFLAGS"

            
            fi


            # We must check for the threads library under a number of different

            
            # names; the ordering is very important because some systems

            
            # (e.g. DEC) have both -lpthread and -lpthreads, where one of the

            
            # libraries is broken (non-POSIX).


            # Create a list of thread flags to try.  Items starting with a "-" are

            
            # C compiler flags, and other items are library names, except for "none"

            
            # which indicates that we try without any flags at all, and "pthread-config"

            
            # which is a program returning the flags for the Pth emulation library.


            ax_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"


            # The ordering *is* (sometimes) important.  Some notes on the

            
            # individual items follow:


            # pthreads: AIX (must check this before -lpthread)

            
            # none: in case threads are in libc; should be tried before -Kthread and

            
            #       other compiler flags to prevent continual compiler warnings

            
            # -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)

            
            # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)

            
            # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)

            
            # -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)

            
            # -pthreads: Solaris/gcc

            
            # -mthreads: Mingw32/gcc, Lynx/gcc

            
            # -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it

            
            #      doesn't hurt to check since this sometimes defines pthreads too;

            
            #      also defines -D_REENTRANT)

            
            #      ... -mt is also the pthreads flag for HP/aCC

            
            # pthread: Linux, etcetera

            
            # --thread-safe: KAI C++

            
            # pthread-config: use pthread-config program (for GNU Pth library)


            case ${host_os} in

            
                    solaris*)


                    # On Solaris (at least, for some versions), libc contains stubbed

            
                    # (non-functional) versions of the pthreads routines, so link-based

            
                    # tests will erroneously succeed.  (We need to link with -pthreads/-mt/

            
                    # -lpthread.)  (The stubs are missing pthread_cleanup_push, or rather

            
                    # a function called by this macro, so we could check for that, but

            
                    # who knows whether they'll stub that too in a future libc.)  So,

            
                    # we'll just look for -pthreads and -lpthread first:


                    ax_pthread_flags="-pthreads pthread -mt -pthread $ax_pthread_flags"

            
                    ;;


                    darwin*)

            
                    ax_pthread_flags="-pthread $ax_pthread_flags"

            
                    ;;

            
            esac


            if test x"$ax_pthread_ok" = xno; then

            
            for flag in $ax_pthread_flags; do


                    case $flag in

            
                            none)

            
                            AC_MSG_CHECKING([whether pthreads work without any flags])

            
                            ;;


                            -*)

            
                            AC_MSG_CHECKING([whether pthreads work with $flag])

            
                            PTHREAD_CFLAGS="$flag"

            
                            ;;


                            pthread-config)

            
                            AC_CHECK_PROG(ax_pthread_config, pthread-config, yes, no)

            
                            if test x"$ax_pthread_config" = xno; then continue; fi

            
                            PTHREAD_CFLAGS="`pthread-config --cflags`"

            
                            PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"

            
                            ;;


                            *)

            
                            AC_MSG_CHECKING([for the pthreads library -l$flag])

            
                            PTHREAD_LIBS="-l$flag"

            
                            ;;

            
                    esac


                    save_LIBS="$LIBS"

            
                    save_CFLAGS="$CFLAGS"

            
                    LIBS="$PTHREAD_LIBS $LIBS"

            
                    CFLAGS="$CFLAGS $PTHREAD_CFLAGS"


                    # Check for various functions.  We must include pthread.h,

            
                    # since some functions may be macros.  (On the Sequent, we

            
                    # need a special flag -Kthread to make this header compile.)

            
                    # We check for pthread_join because it is in -lpthread on IRIX

            
                    # while pthread_create is in libc.  We check for pthread_attr_init

            
                    # due to DEC craziness with -lpthreads.  We check for

            
                    # pthread_cleanup_push because it is one of the few pthread

            
                    # functions on Solaris that doesn't have a non-functional libc stub.

            
                    # We try pthread_create on general principles.

            
                    AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>

            
                                    static void routine(void *a) { a = 0; }

            
                                    static void *start_routine(void *a) { return a; }],

            
                                   [pthread_t th; pthread_attr_t attr;

            
                                    pthread_create(&th, 0, start_routine, 0);

            
                                    pthread_join(th, 0);

            
                                    pthread_attr_init(&attr);

            
                                    pthread_cleanup_push(routine, 0);

            
                                    pthread_cleanup_pop(0) /* ; */])],

            
                            [ax_pthread_ok=yes],

            
                            [])


                    LIBS="$save_LIBS"

            
                    CFLAGS="$save_CFLAGS"


                    AC_MSG_RESULT($ax_pthread_ok)

            
                    if test "x$ax_pthread_ok" = xyes; then

            
                            break;

            
                    fi


                    PTHREAD_LIBS=""

            
                    PTHREAD_CFLAGS=""

            
            done

            
            fi


            # Various other checks:

            
            if test "x$ax_pthread_ok" = xyes; then

            
                    save_LIBS="$LIBS"

            
                    LIBS="$PTHREAD_LIBS $LIBS"

            
                    save_CFLAGS="$CFLAGS"

            
                    CFLAGS="$CFLAGS $PTHREAD_CFLAGS"


                    # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.

            
                    AC_MSG_CHECKING([for joinable pthread attribute])

            
                    attr_name=unknown

            
                    for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do

            
                        AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],

            
                                       [int attr = $attr; return attr /* ; */])],

            
                            [attr_name=$attr; break],

            
                            [])

            
                    done

            
                    AC_MSG_RESULT($attr_name)

            
                    if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then

            
                        AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,

            
                                           [Define to necessary symbol if this constant

            
                                            uses a non-standard name on your system.])

            
                    fi


                    AC_MSG_CHECKING([if more special flags are required for pthreads])

            
                    flag=no

            
                    case ${host_os} in

            
                        aix* | freebsd* | darwin*) flag="-D_THREAD_SAFE";;

            
                        osf* | hpux*) flag="-D_REENTRANT";;

            
                        solaris*)

            
                        if test "$GCC" = "yes"; then

            
                            flag="-D_REENTRANT"

            
                        else

            
                            flag="-mt -D_REENTRANT"

            
                        fi

            
                        ;;

            
                    esac

            
                    AC_MSG_RESULT(${flag})

            
                    if test "x$flag" != xno; then

            
                        PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"

            
                    fi


                    AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],

            
                        ax_cv_PTHREAD_PRIO_INHERIT, [

            
                            AC_LINK_IFELSE([

            
                                AC_LANG_PROGRAM([[#include <pthread.h>]], [[int i = PTHREAD_PRIO_INHERIT;]])],

            
                                [ax_cv_PTHREAD_PRIO_INHERIT=yes],

            
                                [ax_cv_PTHREAD_PRIO_INHERIT=no])

            
                        ])

            
                    AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes"],

            
                        AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], 1, [Have PTHREAD_PRIO_INHERIT.]))


                    LIBS="$save_LIBS"

            
                    CFLAGS="$save_CFLAGS"


                    # More AIX lossage: must compile with xlc_r or cc_r

            
                    if test x"$GCC" != xyes; then

            
                      AC_CHECK_PROGS(PTHREAD_CC, xlc_r cc_r, ${CC})

            
                    else

            
                      PTHREAD_CC=$CC

            
                    fi

            
            else

            
                    PTHREAD_CC="$CC"

            
            fi


            AC_SUBST(PTHREAD_LIBS)

            
            AC_SUBST(PTHREAD_CFLAGS)

            
            AC_SUBST(PTHREAD_CC)


            # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:

            
            if test x"$ax_pthread_ok" = xyes; then

            
                    ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])

            
                    :

            
            else

            
                    ax_pthread_ok=no

            
                    $2

            
            fi

            
            AC_LANG_POP

            
            ])dnl AX_PTHREAD
	# ===========================================================================
	# http://www.gnu.org/software/autoconf-archive/ax_pthread.html
	# ===========================================================================
	#
	# SYNOPSIS
	#
	# AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
	#
	# DESCRIPTION
	#
	# This macro figures out how to build C programs using POSIX threads. It
	# sets the PTHREAD_LIBS output variable to the threads library and linker
	# flags, and the PTHREAD_CFLAGS output variable to any special C compiler
	# flags that are needed. (The user can also force certain compiler
	# flags/libs to be tested by setting these environment variables.)
	#
	# Also sets PTHREAD_CC to any special C compiler that is needed for
	# multi-threaded programs (defaults to the value of CC otherwise). (This
	# is necessary on AIX to use the special cc_r compiler alias.)
	#
	# NOTE: You are assumed to not only compile your program with these flags,
	# but also link it with them as well. e.g. you should link with
	# $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
	#
	# If you are only building threads programs, you may wish to use these
	# variables in your default LIBS, CFLAGS, and CC:
	#
	# LIBS="$PTHREAD_LIBS $LIBS"
	# CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
	# CC="$PTHREAD_CC"
	#
	# In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
	# has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to that name
	# (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
	#
	# Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
	# PTHREAD_PRIO_INHERIT symbol is defined when compiling with
	# PTHREAD_CFLAGS.
	#
	# ACTION-IF-FOUND is a list of shell commands to run if a threads library
	# is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
	# is not found. If ACTION-IF-FOUND is not specified, the default action
	# will define HAVE_PTHREAD.
	#
	# Please let the authors know if this macro fails on any platform, or if
	# you have any other suggestions or comments. This macro was based on work
	# by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
	# from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
	# Alejandro Forero Cuervo to the autoconf macro repository. We are also
	# grateful for the helpful feedback of numerous users.
	#
	# Updated for Autoconf 2.68 by Daniel Richard G.
	#
	# LICENSE
	#
	# Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
	# Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
	#
	# This program is free software: you can redistribute it and/or modify it
	# under the terms of the GNU General Public License as published by the
	# Free Software Foundation, either version 3 of the License, or (at your
	# option) any later version.
	#
	# This program is distributed in the hope that it will be useful, but
	# WITHOUT ANY WARRANTY; without even the implied warranty of
	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
	# Public License for more details.
	#
	# You should have received a copy of the GNU General Public License along
	# with this program. If not, see <http://www.gnu.org/licenses/>.
	#
	# As a special exception, the respective Autoconf Macro's copyright owner
	# gives unlimited permission to copy, distribute and modify the configure
	# scripts that are the output of Autoconf when processing the Macro. You
	# need not follow the terms of the GNU General Public License when using
	# or distributing such scripts, even though portions of the text of the
	# Macro appear in them. The GNU General Public License (GPL) does govern
	# all other use of the material that constitutes the Autoconf Macro.
	#
	# This special exception to the GPL applies to versions of the Autoconf
	# Macro released by the Autoconf Archive. When you make and distribute a
	# modified version of the Autoconf Macro, you may extend this special
	# exception to the GPL to apply to your modified version as well.

	#serial 18

	AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
	AC_DEFUN([AX_PTHREAD], [
	AC_REQUIRE([AC_CANONICAL_HOST])
	AC_LANG_PUSH([C])
	ax_pthread_ok=no

	# We used to check for pthread.h first, but this fails if pthread.h
	# requires special compiler flags (e.g. on True64 or Sequent).
	# It gets checked for in the link test anyway.

	# First of all, check if the user has set any of the PTHREAD_LIBS,
	# etcetera environment variables, and if threads linking works using
	# them:
	if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
	save_CFLAGS="$CFLAGS"
	CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
	save_LIBS="$LIBS"
	LIBS="$PTHREAD_LIBS $LIBS"
	AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
	AC_TRY_LINK_FUNC(pthread_join, ax_pthread_ok=yes)
	AC_MSG_RESULT($ax_pthread_ok)
	if test x"$ax_pthread_ok" = xno; then
	PTHREAD_LIBS=""
	PTHREAD_CFLAGS=""
	fi
	LIBS="$save_LIBS"
	CFLAGS="$save_CFLAGS"
	fi

	# We must check for the threads library under a number of different
	# names; the ordering is very important because some systems
	# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
	# libraries is broken (non-POSIX).

	# Create a list of thread flags to try. Items starting with a "-" are
	# C compiler flags, and other items are library names, except for "none"
	# which indicates that we try without any flags at all, and "pthread-config"
	# which is a program returning the flags for the Pth emulation library.

	ax_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"

	# The ordering is (sometimes) important. Some notes on the
	# individual items follow:

	# pthreads: AIX (must check this before -lpthread)
	# none: in case threads are in libc; should be tried before -Kthread and
	# other compiler flags to prevent continual compiler warnings
	# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
	# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
	# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
	# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
	# -pthreads: Solaris/gcc
	# -mthreads: Mingw32/gcc, Lynx/gcc
	# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
	# doesn't hurt to check since this sometimes defines pthreads too;
	# also defines -D_REENTRANT)
	# ... -mt is also the pthreads flag for HP/aCC
	# pthread: Linux, etcetera
	# --thread-safe: KAI C++
	# pthread-config: use pthread-config program (for GNU Pth library)

	case ${host_os} in
	solaris*)

	# On Solaris (at least, for some versions), libc contains stubbed
	# (non-functional) versions of the pthreads routines, so link-based
	# tests will erroneously succeed. (We need to link with -pthreads/-mt/
	# -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
	# a function called by this macro, so we could check for that, but
	# who knows whether they'll stub that too in a future libc.) So,
	# we'll just look for -pthreads and -lpthread first:

	ax_pthread_flags="-pthreads pthread -mt -pthread $ax_pthread_flags"
	;;

	darwin*)
	ax_pthread_flags="-pthread $ax_pthread_flags"
	;;
	esac

	if test x"$ax_pthread_ok" = xno; then
	for flag in $ax_pthread_flags; do

	case $flag in
	none)
	AC_MSG_CHECKING([whether pthreads work without any flags])
	;;

	-*)
	AC_MSG_CHECKING([whether pthreads work with $flag])
	PTHREAD_CFLAGS="$flag"
	;;

	pthread-config)
	AC_CHECK_PROG(ax_pthread_config, pthread-config, yes, no)
	if test x"$ax_pthread_config" = xno; then continue; fi
	PTHREAD_CFLAGS="`pthread-config --cflags`"
	PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
	;;

	*)
	AC_MSG_CHECKING([for the pthreads library -l$flag])
	PTHREAD_LIBS="-l$flag"
	;;
	esac

	save_LIBS="$LIBS"
	save_CFLAGS="$CFLAGS"
	LIBS="$PTHREAD_LIBS $LIBS"
	CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

	# Check for various functions. We must include pthread.h,
	# since some functions may be macros. (On the Sequent, we
	# need a special flag -Kthread to make this header compile.)
	# We check for pthread_join because it is in -lpthread on IRIX
	# while pthread_create is in libc. We check for pthread_attr_init
	# due to DEC craziness with -lpthreads. We check for
	# pthread_cleanup_push because it is one of the few pthread
	# functions on Solaris that doesn't have a non-functional libc stub.
	# We try pthread_create on general principles.
	AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
	static void routine(void *a) { a = 0; }
	static void start_routine(void a) { return a; }],
	[pthread_t th; pthread_attr_t attr;
	pthread_create(&th, 0, start_routine, 0);
	pthread_join(th, 0);
	pthread_attr_init(&attr);
	pthread_cleanup_push(routine, 0);
	pthread_cleanup_pop(0) /* ; */])],
	[ax_pthread_ok=yes],
	[])

	LIBS="$save_LIBS"
	CFLAGS="$save_CFLAGS"

	AC_MSG_RESULT($ax_pthread_ok)
	if test "x$ax_pthread_ok" = xyes; then
	break;
	fi

	PTHREAD_LIBS=""
	PTHREAD_CFLAGS=""
	done
	fi

	# Various other checks:
	if test "x$ax_pthread_ok" = xyes; then
	save_LIBS="$LIBS"
	LIBS="$PTHREAD_LIBS $LIBS"
	save_CFLAGS="$CFLAGS"
	CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

	# Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
	AC_MSG_CHECKING([for joinable pthread attribute])
	attr_name=unknown
	for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
	AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
	[int attr = $attr; return attr /* ; */])],
	[attr_name=$attr; break],
	[])
	done
	AC_MSG_RESULT($attr_name)
	if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then
	AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,
	[Define to necessary symbol if this constant
	uses a non-standard name on your system.])
	fi

	AC_MSG_CHECKING([if more special flags are required for pthreads])
	flag=no
	case ${host_os} in
	aix* \| freebsd* \| darwin*) flag="-D_THREAD_SAFE";;
	osf* \| hpux*) flag="-D_REENTRANT";;
	solaris*)
	if test "$GCC" = "yes"; then
	flag="-D_REENTRANT"
	else
	flag="-mt -D_REENTRANT"
	fi
	;;
	esac
	AC_MSG_RESULT(${flag})
	if test "x$flag" != xno; then
	PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
	fi

	AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
	ax_cv_PTHREAD_PRIO_INHERIT, [
	AC_LINK_IFELSE([
	AC_LANG_PROGRAM([[#include <pthread.h>]], [[int i = PTHREAD_PRIO_INHERIT;]])],
	[ax_cv_PTHREAD_PRIO_INHERIT=yes],
	[ax_cv_PTHREAD_PRIO_INHERIT=no])
	])
	AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes"],
	AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], 1, [Have PTHREAD_PRIO_INHERIT.]))

	LIBS="$save_LIBS"
	CFLAGS="$save_CFLAGS"

	# More AIX lossage: must compile with xlc_r or cc_r
	if test x"$GCC" != xyes; then
	AC_CHECK_PROGS(PTHREAD_CC, xlc_r cc_r, ${CC})
	else
	PTHREAD_CC=$CC
	fi
	else
	PTHREAD_CC="$CC"
	fi

	AC_SUBST(PTHREAD_LIBS)
	AC_SUBST(PTHREAD_CFLAGS)
	AC_SUBST(PTHREAD_CC)

	# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
	if test x"$ax_pthread_ok" = xyes; then
	ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
	:
	else
	ax_pthread_ok=no
	$2
	fi
	AC_LANG_POP
	])dnl AX_PTHREAD