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# threadlib.m4 serial 5 (gettext-0.18)
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dnl Copyright (C) 2005-2010 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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dnl Tests for a multithreading library to be used.
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dnl Defines at most one of the macros USE_POSIX_THREADS, USE_SOLARIS_THREADS,
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dnl USE_PTH_THREADS, USE_WIN32_THREADS
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dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
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dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
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dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for
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dnl programs that really need multithread functionality. The difference
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dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
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dnl symbols, typically LIBTHREAD="" whereas LIBMULTITHREAD="-lpthread".
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dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
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dnl multithread-safe programs.
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AC_DEFUN([gl_THREADLIB_EARLY],
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AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
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dnl The guts of gl_THREADLIB_EARLY. Needs to be expanded only once.
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AC_DEFUN([gl_THREADLIB_EARLY_BODY],
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dnl Ordering constraints: This macro modifies CPPFLAGS in a way that
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dnl influences the result of the autoconf tests that test for *_unlocked
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dnl declarations, on AIX 5 at least. Therefore it must come early.
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AC_BEFORE([$0], [gl_FUNC_GLIBC_UNLOCKED_IO])dnl
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AC_BEFORE([$0], [gl_ARGP])dnl
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AC_REQUIRE([AC_CANONICAL_HOST])
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dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems.
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dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
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m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
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[AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
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[AC_REQUIRE([AC_GNU_SOURCE])])
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dnl Check for multithreading.
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m4_divert_text([DEFAULTS], [gl_use_threads_default=])
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AC_ARG_ENABLE([threads],
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AC_HELP_STRING([--enable-threads={posix|solaris|pth|win32}], [specify multithreading API])
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AC_HELP_STRING([--disable-threads], [build without multithread safety]),
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[gl_use_threads=$enableval],
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[if test -n "$gl_use_threads_default"; then
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gl_use_threads="$gl_use_threads_default"
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dnl Disable multithreading by default on OSF/1, because it interferes
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dnl with fork()/exec(): When msgexec is linked with -lpthread, its
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dnl child process gets an endless segmentation fault inside execvp().
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dnl Disable multithreading by default on Cygwin 1.5.x, because it has
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dnl bugs that lead to endless loops or crashes. See
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dnl <http://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
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osf*) gl_use_threads=no ;;
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1.[0-5].*) gl_use_threads=no ;;
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*) gl_use_threads=yes ;;
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*) gl_use_threads=yes ;;
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if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
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# For using <pthread.h>:
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# On OSF/1, the compiler needs the flag -D_REENTRANT so that it
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# groks <pthread.h>. cc also understands the flag -pthread, but
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# we don't use it because 1. gcc-2.95 doesn't understand -pthread,
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# 2. putting a flag into CPPFLAGS that has an effect on the linker
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# causes the AC_TRY_LINK test below to succeed unexpectedly,
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# leading to wrong values of LIBTHREAD and LTLIBTHREAD.
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CPPFLAGS="$CPPFLAGS -D_REENTRANT"
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# Some systems optimize for single-threaded programs by default, and
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# need special flags to disable these optimizations. For example, the
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# definition of 'errno' in <errno.h>.
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aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
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solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
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dnl The guts of gl_THREADLIB. Needs to be expanded only once.
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AC_DEFUN([gl_THREADLIB_BODY],
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AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
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if test "$gl_use_threads" != no; then
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dnl Check whether the compiler and linker support weak declarations.
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AC_CACHE_CHECK([whether imported symbols can be declared weak],
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dnl First, test whether the compiler accepts it syntactically.
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AC_TRY_LINK([extern void xyzzy ();
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#pragma weak xyzzy], [xyzzy();], [gl_cv_have_weak=maybe])
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if test $gl_cv_have_weak = maybe; then
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dnl Second, test whether it actually works. On Cygwin 1.7.2, with
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dnl gcc 4.3, symbols declared weak always evaluate to the address 0.
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return (fputs == NULL);
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}], [gl_cv_have_weak=yes], [gl_cv_have_weak=no],
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[dnl When cross-compiling, assume that only ELF platforms support
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AC_EGREP_CPP([Extensible Linking Format],
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Extensible Linking Format
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[gl_cv_have_weak="guessing yes"],
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[gl_cv_have_weak="guessing no"])
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if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
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# On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
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# it groks <pthread.h>. It's added above, in gl_THREADLIB_EARLY_BODY.
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AC_CHECK_HEADER([pthread.h],
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[gl_have_pthread_h=yes], [gl_have_pthread_h=no])
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if test "$gl_have_pthread_h" = yes; then
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# Other possible tests:
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# -lpthreads (FSU threads, PCthreads)
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# Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
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# in libc. IRIX 6.5 has the first one in both libc and libpthread, but
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# the second one only in libpthread, and lock.c needs it.
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AC_TRY_LINK([#include <pthread.h>],
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[pthread_mutex_lock((pthread_mutex_t*)0);
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pthread_mutexattr_init((pthread_mutexattr_t*)0);],
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[gl_have_pthread=yes])
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# Test for libpthread by looking for pthread_kill. (Not pthread_self,
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# since it is defined as a macro on OSF/1.)
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if test -n "$gl_have_pthread"; then
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# The program links fine without libpthread. But it may actually
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# need to link with libpthread in order to create multiple threads.
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AC_CHECK_LIB([pthread], [pthread_kill],
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[LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread
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# On Solaris and HP-UX, most pthread functions exist also in libc.
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# Therefore pthread_in_use() needs to actually try to create a
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# thread: pthread_create from libc will fail, whereas
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# pthread_create will actually create a thread.
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AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
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[Define if the pthread_in_use() detection is hard.])
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# Some library is needed. Try libpthread and libc_r.
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AC_CHECK_LIB([pthread], [pthread_kill],
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LIBTHREAD=-lpthread LTLIBTHREAD=-lpthread
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LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread])
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if test -z "$gl_have_pthread"; then
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AC_CHECK_LIB([c_r], [pthread_kill],
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LIBTHREAD=-lc_r LTLIBTHREAD=-lc_r
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LIBMULTITHREAD=-lc_r LTLIBMULTITHREAD=-lc_r])
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if test -n "$gl_have_pthread"; then
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AC_DEFINE([USE_POSIX_THREADS], [1],
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[Define if the POSIX multithreading library can be used.])
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if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
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if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
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AC_DEFINE([USE_POSIX_THREADS_WEAK], [1],
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[Define if references to the POSIX multithreading library should be made weak.])
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if test -z "$gl_have_pthread"; then
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if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then
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gl_have_solaristhread=
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LIBS="$LIBS -lthread"
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AC_TRY_LINK([#include <thread.h>
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[gl_have_solaristhread=yes])
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if test -n "$gl_have_solaristhread"; then
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gl_threads_api=solaris
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LIBMULTITHREAD="$LIBTHREAD"
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LTLIBMULTITHREAD="$LTLIBTHREAD"
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AC_DEFINE([USE_SOLARIS_THREADS], [1],
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[Define if the old Solaris multithreading library can be used.])
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if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
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AC_DEFINE([USE_SOLARIS_THREADS_WEAK], [1],
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[Define if references to the old Solaris multithreading library should be made weak.])
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if test "$gl_use_threads" = pth; then
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gl_save_CPPFLAGS="$CPPFLAGS"
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AC_LIB_LINKFLAGS([pth])
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AC_TRY_LINK([#include <pth.h>], [pth_self();], [gl_have_pth=yes])
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if test -n "$gl_have_pth"; then
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LTLIBTHREAD="$LTLIBPTH"
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LIBMULTITHREAD="$LIBTHREAD"
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LTLIBMULTITHREAD="$LTLIBTHREAD"
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AC_DEFINE([USE_PTH_THREADS], [1],
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[Define if the GNU Pth multithreading library can be used.])
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if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
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if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
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AC_DEFINE([USE_PTH_THREADS_WEAK], [1],
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[Define if references to the GNU Pth multithreading library should be made weak.])
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CPPFLAGS="$gl_save_CPPFLAGS"
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if test -z "$gl_have_pthread"; then
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if test "$gl_use_threads" = yes || test "$gl_use_threads" = win32; then
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if { case "$host_os" in
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AC_DEFINE([USE_WIN32_THREADS], [1],
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[Define if the Win32 multithreading API can be used.])
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AC_MSG_CHECKING([for multithread API to use])
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AC_MSG_RESULT([$gl_threads_api])
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AC_SUBST([LIBTHREAD])
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AC_SUBST([LTLIBTHREAD])
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AC_SUBST([LIBMULTITHREAD])
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AC_SUBST([LTLIBMULTITHREAD])
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AC_DEFUN([gl_THREADLIB],
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AC_REQUIRE([gl_THREADLIB_EARLY])
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AC_REQUIRE([gl_THREADLIB_BODY])
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dnl gl_DISABLE_THREADS
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dnl ------------------
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dnl Sets the gl_THREADLIB default so that threads are not used by default.
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dnl The user can still override it at installation time, by using the
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dnl configure option '--enable-threads'.
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AC_DEFUN([gl_DISABLE_THREADS], [
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m4_divert_text([INIT_PREPARE], [gl_use_threads_default=no])
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dnl Survey of platforms:
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dnl Platform Available Compiler Supports test-lock
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dnl flavours option weak result
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dnl --------------- --------- --------- -------- ---------
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dnl Linux 2.4/glibc posix -lpthread Y OK
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dnl GNU Hurd/glibc posix
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dnl FreeBSD 5.3 posix -lc_r Y
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dnl posix -lpthread ? Y
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dnl FreeBSD 5.2 posix -lc_r Y
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dnl FreeBSD 4.0,4.10 posix -lc_r Y OK
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dnl OpenBSD 3.4 posix -lpthread Y OK
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dnl MacOS X 10.[123] posix -lpthread Y OK
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dnl Solaris 7,8,9 posix -lpthread Y Sol 7,8: 0.0; Sol 9: OK
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dnl solaris -lthread Y Sol 7,8: 0.0; Sol 9: OK
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dnl HP-UX 11 posix -lpthread N (cc) OK
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dnl IRIX 6.5 posix -lpthread Y 0.5
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dnl AIX 4.3,5.1 posix -lpthread N AIX 4: 0.5; AIX 5: OK
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dnl OSF/1 4.0,5.1 posix -pthread (cc) N OK
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dnl -lpthread (gcc) Y
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dnl Cygwin posix -lpthread Y OK
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dnl Any of the above pth -lpth 0.0
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dnl The test-lock result shows what happens if in test-lock.c EXPLICIT_YIELD is
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dnl OK if all three tests terminate OK,
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dnl 0.5 if the first test terminates OK but the second one loops endlessly,
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dnl 0.0 if the first test already loops endlessly.
added
removed
m4/threadlib.m4
