m4/ax_pthread.m4

   1 # ===========================================================================
   2 #        https://www.gnu.org/software/autoconf-archive/ax_pthread.html
   3 # ===========================================================================
   4 #
   5 # SYNOPSIS
   6 #
   7 #   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
   8 #
   9 # DESCRIPTION
  10 #
  11 #   This macro figures out how to build C programs using POSIX threads. It
  12 #   sets the PTHREAD_LIBS output variable to the threads library and linker
  13 #   flags, and the PTHREAD_CFLAGS output variable to any special C compiler
  14 #   flags that are needed. (The user can also force certain compiler
  15 #   flags/libs to be tested by setting these environment variables.)
  16 #
  17 #   Also sets PTHREAD_CC to any special C compiler that is needed for
  18 #   multi-threaded programs (defaults to the value of CC otherwise). (This
  19 #   is necessary on AIX to use the special cc_r compiler alias.)
  20 #
  21 #   NOTE: You are assumed to not only compile your program with these flags,
  22 #   but also to link with them as well. For example, you might link with
  23 #   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
  24 #
  25 #   If you are only building threaded programs, you may wish to use these
  26 #   variables in your default LIBS, CFLAGS, and CC:
  27 #
  28 #     LIBS="$PTHREAD_LIBS $LIBS"
  29 #     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
  30 #     CC="$PTHREAD_CC"
  31 #
  32 #   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
  33 #   has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
  34 #   that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
  35 #
  36 #   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
  37 #   PTHREAD_PRIO_INHERIT symbol is defined when compiling with
  38 #   PTHREAD_CFLAGS.
  39 #
  40 #   ACTION-IF-FOUND is a list of shell commands to run if a threads library
  41 #   is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
  42 #   is not found. If ACTION-IF-FOUND is not specified, the default action
  43 #   will define HAVE_PTHREAD.
  44 #
  45 #   Please let the authors know if this macro fails on any platform, or if
  46 #   you have any other suggestions or comments. This macro was based on work
  47 #   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
  48 #   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
  49 #   Alejandro Forero Cuervo to the autoconf macro repository. We are also
  50 #   grateful for the helpful feedback of numerous users.
  51 #
  52 #   Updated for Autoconf 2.68 by Daniel Richard G.
  53 #
  54 # LICENSE
  55 #
  56 #   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
  57 #   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
  58 #   Copyright (c) 2019 Marc Stevens <marc.stevens@cwi.nl>
  59 #
  60 #   This program is free software: you can redistribute it and/or modify it
  61 #   under the terms of the GNU General Public License as published by the
  62 #   Free Software Foundation, either version 3 of the License, or (at your
  63 #   option) any later version.
  64 #
  65 #   This program is distributed in the hope that it will be useful, but
  66 #   WITHOUT ANY WARRANTY; without even the implied warranty of
  67 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
  68 #   Public License for more details.
  69 #
  70 #   You should have received a copy of the GNU General Public License along
  71 #   with this program. If not, see <https://www.gnu.org/licenses/>.
  72 #
  73 #   As a special exception, the respective Autoconf Macro's copyright owner
  74 #   gives unlimited permission to copy, distribute and modify the configure
  75 #   scripts that are the output of Autoconf when processing the Macro. You
  76 #   need not follow the terms of the GNU General Public License when using
  77 #   or distributing such scripts, even though portions of the text of the
  78 #   Macro appear in them. The GNU General Public License (GPL) does govern
  79 #   all other use of the material that constitutes the Autoconf Macro.
  80 #
  81 #   This special exception to the GPL applies to versions of the Autoconf
  82 #   Macro released by the Autoconf Archive. When you make and distribute a
  83 #   modified version of the Autoconf Macro, you may extend this special
  84 #   exception to the GPL to apply to your modified version as well.
  85
  86 #serial 27
  87
  88 AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
  89 AC_DEFUN([AX_PTHREAD], [
  90 AC_REQUIRE([AC_CANONICAL_HOST])
  91 AC_REQUIRE([AC_PROG_CC])
  92 AC_REQUIRE([AC_PROG_SED])
  93 AC_LANG_PUSH([C])
  94 ax_pthread_ok=no
  95
  96 # We used to check for pthread.h first, but this fails if pthread.h
  97 # requires special compiler flags (e.g. on Tru64 or Sequent).
  98 # It gets checked for in the link test anyway.
  99
 100 # First of all, check if the user has set any of the PTHREAD_LIBS,
 101 # etcetera environment variables, and if threads linking works using
 102 # them:
 103 if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
 104         ax_pthread_save_CC="$CC"
 105         ax_pthread_save_CFLAGS="$CFLAGS"
 106         ax_pthread_save_LIBS="$LIBS"
 107         AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
 108         CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
 109         LIBS="$PTHREAD_LIBS $LIBS"
 110         AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
 111         AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
 112         AC_MSG_RESULT([$ax_pthread_ok])
 113         if test "x$ax_pthread_ok" = "xno"; then
 114                 PTHREAD_LIBS=""
 115                 PTHREAD_CFLAGS=""
 116         fi
 117         CC="$ax_pthread_save_CC"
 118         CFLAGS="$ax_pthread_save_CFLAGS"
 119         LIBS="$ax_pthread_save_LIBS"
 120 fi
 121
 122 # We must check for the threads library under a number of different
 123 # names; the ordering is very important because some systems
 124 # (e.g. DEC) have both -lpthread and -lpthreads, where one of the
 125 # libraries is broken (non-POSIX).
 126
 127 # Create a list of thread flags to try. Items with a "," contain both
 128 # C compiler flags (before ",") and linker flags (after ","). Other items
 129 # starting with a "-" are C compiler flags, and remaining items are
 130 # library names, except for "none" which indicates that we try without
 131 # any flags at all, and "pthread-config" which is a program returning
 132 # the flags for the Pth emulation library.
 133
 134 ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
 135
 136 # The ordering *is* (sometimes) important.  Some notes on the
 137 # individual items follow:
 138
 139 # pthreads: AIX (must check this before -lpthread)
 140 # none: in case threads are in libc; should be tried before -Kthread and
 141 #       other compiler flags to prevent continual compiler warnings
 142 # -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
 143 # -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
 144 #           (Note: HP C rejects this with "bad form for `-t' option")
 145 # -pthreads: Solaris/gcc (Note: HP C also rejects)
 146 # -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
 147 #      doesn't hurt to check since this sometimes defines pthreads and
 148 #      -D_REENTRANT too), HP C (must be checked before -lpthread, which
 149 #      is present but should not be used directly; and before -mthreads,
 150 #      because the compiler interprets this as "-mt" + "-hreads")
 151 # -mthreads: Mingw32/gcc, Lynx/gcc
 152 # pthread: Linux, etcetera
 153 # --thread-safe: KAI C++
 154 # pthread-config: use pthread-config program (for GNU Pth library)
 155
 156 case $host_os in
 157
 158         freebsd*)
 159
 160         # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
 161         # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
 162
 163         ax_pthread_flags="-kthread lthread $ax_pthread_flags"
 164         ;;
 165
 166         hpux*)
 167
 168         # From the cc(1) man page: "[-mt] Sets various -D flags to enable
 169         # multi-threading and also sets -lpthread."
 170
 171         ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
 172         ;;
 173
 174         openedition*)
 175
 176         # IBM z/OS requires a feature-test macro to be defined in order to
 177         # enable POSIX threads at all, so give the user a hint if this is
 178         # not set. (We don't define these ourselves, as they can affect
 179         # other portions of the system API in unpredictable ways.)
 180
 181         AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
 182             [
 183 #            if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
 184              AX_PTHREAD_ZOS_MISSING
 185 #            endif
 186             ],
 187             [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
 188         ;;
 189
 190         solaris*)
 191
 192         # On Solaris (at least, for some versions), libc contains stubbed
 193         # (non-functional) versions of the pthreads routines, so link-based
 194         # tests will erroneously succeed. (N.B.: The stubs are missing
 195         # pthread_cleanup_push, or rather a function called by this macro,
 196         # so we could check for that, but who knows whether they'll stub
 197         # that too in a future libc.)  So we'll check first for the
 198         # standard Solaris way of linking pthreads (-mt -lpthread).
 199
 200         ax_pthread_flags="-mt,-lpthread pthread $ax_pthread_flags"
 201         ;;
 202 esac
 203
 204 # Are we compiling with Clang?
 205
 206 AC_CACHE_CHECK([whether $CC is Clang],
 207     [ax_cv_PTHREAD_CLANG],
 208     [ax_cv_PTHREAD_CLANG=no
 209      # Note that Autoconf sets GCC=yes for Clang as well as GCC
 210      if test "x$GCC" = "xyes"; then
 211         AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
 212             [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
 213 #            if defined(__clang__) && defined(__llvm__)
 214              AX_PTHREAD_CC_IS_CLANG
 215 #            endif
 216             ],
 217             [ax_cv_PTHREAD_CLANG=yes])
 218      fi
 219     ])
 220 ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
 221
 222
 223 # GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
 224
 225 # Note that for GCC and Clang -pthread generally implies -lpthread,
 226 # except when -nostdlib is passed.
 227 # This is problematic using libtool to build C++ shared libraries with pthread:
 228 # [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25460
 229 # [2] https://bugzilla.redhat.com/show_bug.cgi?id=661333
 230 # [3] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=468555
 231 # To solve this, first try -pthread together with -lpthread for GCC
 232
 233 AS_IF([test "x$GCC" = "xyes"],
 234       [ax_pthread_flags="-pthread,-lpthread -pthread -pthreads $ax_pthread_flags"])
 235
 236 # Clang takes -pthread (never supported any other flag), but we'll try with -lpthread first
 237
 238 AS_IF([test "x$ax_pthread_clang" = "xyes"],
 239       [ax_pthread_flags="-pthread,-lpthread -pthread"])
 240
 241
 242 # The presence of a feature test macro requesting re-entrant function
 243 # definitions is, on some systems, a strong hint that pthreads support is
 244 # correctly enabled
 245
 246 case $host_os in
 247         darwin* | hpux* | linux* | osf* | solaris*)
 248         ax_pthread_check_macro="_REENTRANT"
 249         ;;
 250
 251         aix*)
 252         ax_pthread_check_macro="_THREAD_SAFE"
 253         ;;
 254
 255         *)
 256         ax_pthread_check_macro="--"
 257         ;;
 258 esac
 259 AS_IF([test "x$ax_pthread_check_macro" = "x--"],
 260       [ax_pthread_check_cond=0],
 261       [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
 262
 263
 264 if test "x$ax_pthread_ok" = "xno"; then
 265 for ax_pthread_try_flag in $ax_pthread_flags; do
 266
 267         case $ax_pthread_try_flag in
 268                 none)
 269                 AC_MSG_CHECKING([whether pthreads work without any flags])
 270                 ;;
 271
 272                 *,*)
 273                 PTHREAD_CFLAGS=`echo $ax_pthread_try_flag | sed "s/^\(.*\),\(.*\)$/\1/"`
 274                 PTHREAD_LIBS=`echo $ax_pthread_try_flag | sed "s/^\(.*\),\(.*\)$/\2/"`
 275                 AC_MSG_CHECKING([whether pthreads work with "$PTHREAD_CFLAGS" and "$PTHREAD_LIBS"])
 276                 ;;
 277
 278                 -*)
 279                 AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
 280                 PTHREAD_CFLAGS="$ax_pthread_try_flag"
 281                 ;;
 282
 283                 pthread-config)
 284                 AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
 285                 AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
 286                 PTHREAD_CFLAGS="`pthread-config --cflags`"
 287                 PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
 288                 ;;
 289
 290                 *)
 291                 AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
 292                 PTHREAD_LIBS="-l$ax_pthread_try_flag"
 293                 ;;
 294         esac
 295
 296         ax_pthread_save_CFLAGS="$CFLAGS"
 297         ax_pthread_save_LIBS="$LIBS"
 298         CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
 299         LIBS="$PTHREAD_LIBS $LIBS"
 300
 301         # Check for various functions.  We must include pthread.h,
 302         # since some functions may be macros.  (On the Sequent, we
 303         # need a special flag -Kthread to make this header compile.)
 304         # We check for pthread_join because it is in -lpthread on IRIX
 305         # while pthread_create is in libc.  We check for pthread_attr_init
 306         # due to DEC craziness with -lpthreads.  We check for
 307         # pthread_cleanup_push because it is one of the few pthread
 308         # functions on Solaris that doesn't have a non-functional libc stub.
 309         # We try pthread_create on general principles.
 310
 311         AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
 312 #                       if $ax_pthread_check_cond
 313 #                        error "$ax_pthread_check_macro must be defined"
 314 #                       endif
 315                         static void *some_global = NULL;
 316                         static void routine(void *a)
 317                           {
 318                              /* To avoid any unused-parameter or
 319                                 unused-but-set-parameter warning.  */
 320                              some_global = a;
 321                           }
 322                         static void *start_routine(void *a) { return a; }],
 323                        [pthread_t th; pthread_attr_t attr;
 324                         pthread_create(&th, 0, start_routine, 0);
 325                         pthread_join(th, 0);
 326                         pthread_attr_init(&attr);
 327                         pthread_cleanup_push(routine, 0);
 328                         pthread_cleanup_pop(0) /* ; */])],
 329             [ax_pthread_ok=yes],
 330             [])
 331
 332         CFLAGS="$ax_pthread_save_CFLAGS"
 333         LIBS="$ax_pthread_save_LIBS"
 334
 335         AC_MSG_RESULT([$ax_pthread_ok])
 336         AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
 337
 338         PTHREAD_LIBS=""
 339         PTHREAD_CFLAGS=""
 340 done
 341 fi
 342
 343
 344 # Clang needs special handling, because older versions handle the -pthread
 345 # option in a rather... idiosyncratic way
 346
 347 if test "x$ax_pthread_clang" = "xyes"; then
 348
 349         # Clang takes -pthread; it has never supported any other flag
 350
 351         # (Note 1: This will need to be revisited if a system that Clang
 352         # supports has POSIX threads in a separate library.  This tends not
 353         # to be the way of modern systems, but it's conceivable.)
 354
 355         # (Note 2: On some systems, notably Darwin, -pthread is not needed
 356         # to get POSIX threads support; the API is always present and
 357         # active.  We could reasonably leave PTHREAD_CFLAGS empty.  But
 358         # -pthread does define _REENTRANT, and while the Darwin headers
 359         # ignore this macro, third-party headers might not.)
 360
 361         # However, older versions of Clang make a point of warning the user
 362         # that, in an invocation where only linking and no compilation is
 363         # taking place, the -pthread option has no effect ("argument unused
 364         # during compilation").  They expect -pthread to be passed in only
 365         # when source code is being compiled.
 366         #
 367         # Problem is, this is at odds with the way Automake and most other
 368         # C build frameworks function, which is that the same flags used in
 369         # compilation (CFLAGS) are also used in linking.  Many systems
 370         # supported by AX_PTHREAD require exactly this for POSIX threads
 371         # support, and in fact it is often not straightforward to specify a
 372         # flag that is used only in the compilation phase and not in
 373         # linking.  Such a scenario is extremely rare in practice.
 374         #
 375         # Even though use of the -pthread flag in linking would only print
 376         # a warning, this can be a nuisance for well-run software projects
 377         # that build with -Werror.  So if the active version of Clang has
 378         # this misfeature, we search for an option to squash it.
 379
 380         AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
 381             [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
 382             [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
 383              # Create an alternate version of $ac_link that compiles and
 384              # links in two steps (.c -> .o, .o -> exe) instead of one
 385              # (.c -> exe), because the warning occurs only in the second
 386              # step
 387              ax_pthread_save_ac_link="$ac_link"
 388              ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
 389              ax_pthread_link_step=`AS_ECHO(["$ac_link"]) | sed "$ax_pthread_sed"`
 390              ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
 391              ax_pthread_save_CFLAGS="$CFLAGS"
 392              for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
 393                 AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
 394                 CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
 395                 ac_link="$ax_pthread_save_ac_link"
 396                 AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
 397                     [ac_link="$ax_pthread_2step_ac_link"
 398                      AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
 399                          [break])
 400                     ])
 401              done
 402              ac_link="$ax_pthread_save_ac_link"
 403              CFLAGS="$ax_pthread_save_CFLAGS"
 404              AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
 405              ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
 406             ])
 407
 408         case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
 409                 no | unknown) ;;
 410                 *) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
 411         esac
 412
 413 fi # $ax_pthread_clang = yes
 414
 415
 416
 417 # Various other checks:
 418 if test "x$ax_pthread_ok" = "xyes"; then
 419         ax_pthread_save_CFLAGS="$CFLAGS"
 420         ax_pthread_save_LIBS="$LIBS"
 421         CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
 422         LIBS="$PTHREAD_LIBS $LIBS"
 423
 424         # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
 425         AC_CACHE_CHECK([for joinable pthread attribute],
 426             [ax_cv_PTHREAD_JOINABLE_ATTR],
 427             [ax_cv_PTHREAD_JOINABLE_ATTR=unknown
 428              for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
 429                  AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
 430                                                  [int attr = $ax_pthread_attr; return attr /* ; */])],
 431                                 [ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
 432                                 [])
 433              done
 434             ])
 435         AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
 436                test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
 437                test "x$ax_pthread_joinable_attr_defined" != "xyes"],
 438               [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
 439                                   [$ax_cv_PTHREAD_JOINABLE_ATTR],
 440                                   [Define to necessary symbol if this constant
 441                                    uses a non-standard name on your system.])
 442                ax_pthread_joinable_attr_defined=yes
 443               ])
 444
 445         AC_CACHE_CHECK([whether more special flags are required for pthreads],
 446             [ax_cv_PTHREAD_SPECIAL_FLAGS],
 447             [ax_cv_PTHREAD_SPECIAL_FLAGS=no
 448              case $host_os in
 449              solaris*)
 450              ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
 451              ;;
 452              esac
 453             ])
 454         AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
 455                test "x$ax_pthread_special_flags_added" != "xyes"],
 456               [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
 457                ax_pthread_special_flags_added=yes])
 458
 459         AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
 460             [ax_cv_PTHREAD_PRIO_INHERIT],
 461             [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
 462                                              [[int i = PTHREAD_PRIO_INHERIT;
 463                                                return i;]])],
 464                             [ax_cv_PTHREAD_PRIO_INHERIT=yes],
 465                             [ax_cv_PTHREAD_PRIO_INHERIT=no])
 466             ])
 467         AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
 468                test "x$ax_pthread_prio_inherit_defined" != "xyes"],
 469               [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
 470                ax_pthread_prio_inherit_defined=yes
 471               ])
 472
 473         CFLAGS="$ax_pthread_save_CFLAGS"
 474         LIBS="$ax_pthread_save_LIBS"
 475
 476         # More AIX lossage: compile with *_r variant
 477         if test "x$GCC" != "xyes"; then
 478             case $host_os in
 479                 aix*)
 480                 AS_CASE(["x/$CC"],
 481                     [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],
 482                     [#handle absolute path differently from PATH based program lookup
 483                      AS_CASE(["x$CC"],
 484                          [x/*],
 485                          [AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])],
 486                          [AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])])])
 487                 ;;
 488             esac
 489         fi
 490 fi
 491
 492 test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
 493
 494 AC_SUBST([PTHREAD_LIBS])
 495 AC_SUBST([PTHREAD_CFLAGS])
 496 AC_SUBST([PTHREAD_CC])
 497
 498 # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
 499 if test "x$ax_pthread_ok" = "xyes"; then
 500         ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
 501         :
 502 else
 503         ax_pthread_ok=no
 504         $2
 505 fi
 506 AC_LANG_POP
 507 ])dnl AX_PTHREAD