[build-aux] Update Boost & check macros to latest serials

build-aux/m4/ax_boost_base.m4

@@ -33,7 +33,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 23
+#serial 26
 
 AC_DEFUN([AX_BOOST_BASE],
 [
@@ -95,8 +95,8 @@ if test "x$want_boost" = "xyes"; then
       x86_64)
         libsubdirs="lib64 libx32 lib lib64"
         ;;
-      ppc64|s390x|sparc64|aarch64)
+      ppc64|s390x|sparc64|aarch64|ppc64le)
-        libsubdirs="lib64 lib lib64"
+        libsubdirs="lib64 lib lib64 ppc64le"
         ;;
     esac
 
@@ -170,7 +170,7 @@ if test "x$want_boost" = "xyes"; then
         AC_MSG_RESULT(yes)
     succeeded=yes
     found_system=yes
-        ],[:
+        ],[
         ])
     AC_LANG_POP([C++])
 
@@ -179,6 +179,10 @@ if test "x$want_boost" = "xyes"; then
     dnl if we found no boost with system layout we search for boost libraries
     dnl built and installed without the --layout=system option or for a staged(not installed) version
     if test "x$succeeded" != "xyes"; then
+        CPPFLAGS="$CPPFLAGS_SAVED"
+        LDFLAGS="$LDFLAGS_SAVED"
+        BOOST_CPPFLAGS=
+        BOOST_LDFLAGS=
         _version=0
         if test "$ac_boost_path" != ""; then
             if test -d "$ac_boost_path" && test -r "$ac_boost_path"; then
@@ -191,6 +195,12 @@ if test "x$want_boost" = "xyes"; then
                     VERSION_UNDERSCORE=`echo $_version | sed 's/\./_/'`
                     BOOST_CPPFLAGS="-I$ac_boost_path/include/boost-$VERSION_UNDERSCORE"
                 done
+                dnl if nothing found search for layout used in Windows distributions
+                if test -z "$BOOST_CPPFLAGS"; then
+                    if test -d "$ac_boost_path/boost" && test -r "$ac_boost_path/boost"; then
+                        BOOST_CPPFLAGS="-I$ac_boost_path"
+                    fi
+                fi
             fi
         else
             if test "$cross_compiling" != yes; then
@@ -253,7 +263,7 @@ if test "x$want_boost" = "xyes"; then
             AC_MSG_RESULT(yes)
         succeeded=yes
         found_system=yes
-            ],[:
+            ],[
             ])
         AC_LANG_POP([C++])
     fi

build-aux/m4/ax_boost_program_options.m4

@@ -29,7 +29,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 22
+#serial 24
 
 AC_DEFUN([AX_BOOST_PROGRAM_OPTIONS],
 [
@@ -63,9 +63,9 @@ AC_DEFUN([AX_BOOST_PROGRAM_OPTIONS],
 		AC_CACHE_CHECK([whether the Boost::Program_Options library is available],
 					   ax_cv_boost_program_options,
 					   [AC_LANG_PUSH(C++)
-				AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[@%:@include <boost/program_options.hpp>
+				AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[@%:@include <boost/program_options/errors.hpp>
                                                           ]],
-                                  [[boost::program_options::options_description generic("Generic options");
+                                  [[boost::program_options::error err("Error message");
                                    return 0;]])],
                            ax_cv_boost_program_options=yes, ax_cv_boost_program_options=no)
 					AC_LANG_POP([C++])
@@ -74,7 +74,6 @@ AC_DEFUN([AX_BOOST_PROGRAM_OPTIONS],
 				AC_DEFINE(HAVE_BOOST_PROGRAM_OPTIONS,,[define if the Boost::PROGRAM_OPTIONS library is available])
                   BOOSTLIBDIR=`echo $BOOST_LDFLAGS | sed -e 's/@<:@^\/@:>@*//'`
                 if test "x$ax_boost_user_program_options_lib" = "x"; then
-                ax_lib=
                 for libextension in `ls $BOOSTLIBDIR/libboost_program_options*.so* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^lib\(boost_program_options.*\)\.so.*$;\1;'` `ls $BOOSTLIBDIR/libboost_program_options*.dylib* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^lib\(boost_program_options.*\)\.dylib.*$;\1;'` `ls $BOOSTLIBDIR/libboost_program_options*.a* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^lib\(boost_program_options.*\)\.a.*$;\1;'` ; do
                      ax_lib=${libextension}
 				    AC_CHECK_LIB($ax_lib, exit,

build-aux/m4/ax_boost_system.m4

@@ -31,7 +31,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 17
+#serial 18
 
 AC_DEFUN([AX_BOOST_SYSTEM],
 [
@@ -68,9 +68,10 @@ AC_DEFUN([AX_BOOST_SYSTEM],
 					   ax_cv_boost_system,
         [AC_LANG_PUSH([C++])
 			 CXXFLAGS_SAVE=$CXXFLAGS
+			 CXXFLAGS=
 
 			 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[@%:@include <boost/system/error_code.hpp>]],
-                                   [[boost::system::system_category]])],
+				    [[boost::system::error_category *a = 0;]])],
                    ax_cv_boost_system=yes, ax_cv_boost_system=no)
 			 CXXFLAGS=$CXXFLAGS_SAVE
              AC_LANG_POP([C++])

build-aux/m4/ax_check_compile_flag.m4

@@ -4,7 +4,7 @@
 #
 # SYNOPSIS
 #
-#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
 #
 # DESCRIPTION
 #
@@ -19,6 +19,8 @@
 #   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
 #   force the compiler to issue an error when a bad flag is given.
 #
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
 #   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
 #   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
 #
@@ -53,19 +55,19 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 2
+#serial 4
 
 AC_DEFUN([AX_CHECK_COMPILE_FLAG],
-[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
 AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
 AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
   ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
   _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
+  AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
     [AS_VAR_SET(CACHEVAR,[yes])],
     [AS_VAR_SET(CACHEVAR,[no])])
   _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
-AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
+AS_VAR_IF(CACHEVAR,yes,
   [m4_default([$2], :)],
   [m4_default([$3], :)])
 AS_VAR_POPDEF([CACHEVAR])dnl

build-aux/m4/ax_check_link_flag.m4

@@ -4,7 +4,7 @@
 #
 # SYNOPSIS
 #
-#   AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+#   AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
 #
 # DESCRIPTION
 #
@@ -19,6 +19,8 @@
 #   EXTRA-FLAGS FLAG".  This can for example be used to force the linker to
 #   issue an error when a bad flag is given.
 #
+#   INPUT gives an alternative input source to AC_LINK_IFELSE.
+#
 #   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
 #   macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG.
 #
@@ -53,18 +55,19 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 2
+#serial 4
 
 AC_DEFUN([AX_CHECK_LINK_FLAG],
-[AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
 AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
   ax_check_save_flags=$LDFLAGS
   LDFLAGS="$LDFLAGS $4 $1"
-  AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+  AC_LINK_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
     [AS_VAR_SET(CACHEVAR,[yes])],
     [AS_VAR_SET(CACHEVAR,[no])])
   LDFLAGS=$ax_check_save_flags])
-AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
+AS_VAR_IF(CACHEVAR,yes,
   [m4_default([$2], :)],
   [m4_default([$3], :)])
 AS_VAR_POPDEF([CACHEVAR])dnl

build-aux/m4/ax_check_preproc_flag.m4

@@ -4,7 +4,7 @@
 #
 # SYNOPSIS
 #
-#   AX_CHECK_PREPROC_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+#   AX_CHECK_PREPROC_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
 #
 # DESCRIPTION
 #
@@ -19,6 +19,8 @@
 #   "CPPFLAGS EXTRA-FLAGS FLAG".  This can for example be used to force the
 #   preprocessor to issue an error when a bad flag is given.
 #
+#   INPUT gives an alternative input source to AC_PREPROC_IFELSE.
+#
 #   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
 #   macro in sync with AX_CHECK_{COMPILE,LINK}_FLAG.
 #
@@ -53,19 +55,19 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 2
+#serial 4
 
 AC_DEFUN([AX_CHECK_PREPROC_FLAG],
-[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
 AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]cppflags_$4_$1])dnl
 AC_CACHE_CHECK([whether _AC_LANG preprocessor accepts $1], CACHEVAR, [
   ax_check_save_flags=$CPPFLAGS
   CPPFLAGS="$CPPFLAGS $4 $1"
-  AC_PREPROC_IFELSE([AC_LANG_PROGRAM()],
+  AC_PREPROC_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
     [AS_VAR_SET(CACHEVAR,[yes])],
     [AS_VAR_SET(CACHEVAR,[no])])
   CPPFLAGS=$ax_check_save_flags])
-AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
+AS_VAR_IF(CACHEVAR,yes,
   [m4_default([$2], :)],
   [m4_default([$3], :)])
 AS_VAR_POPDEF([CACHEVAR])dnl

build-aux/m4/ax_gcc_func_attribute.m4

@@ -31,6 +31,7 @@
 #    cold
 #    const
 #    constructor
+#    constructor_priority for constructor attribute with priority
 #    deprecated
 #    destructor
 #    dllexport
@@ -73,7 +74,7 @@
 #   and this notice are preserved.  This file is offered as-is, without any
 #   warranty.
 
-#serial 2
+#serial 3
 
 AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
     AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1])
@@ -103,6 +104,9 @@ AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
                 [const], [
                     int foo( void ) __attribute__(($1));
                 ],
+                [constructor_priority], [
+                    int foo( void ) __attribute__((__constructor__(65535/2)));
+                ],
                 [constructor], [
                     int foo( void ) __attribute__(($1));
                 ],
@@ -180,6 +184,8 @@ AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
                 [visibility], [
                     int foo_def( void ) __attribute__(($1("default")));
                     int foo_hid( void ) __attribute__(($1("hidden")));
+                    int foo_int( void ) __attribute__(($1("internal")));
+                    int foo_pro( void ) __attribute__(($1("protected")));
                 ],
                 [warning], [
                     int foo( void ) __attribute__(($1("")));

build-aux/m4/ax_pthread.m4

@@ -19,10 +19,10 @@
 #   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
+#   but also to link with them as well. For example, you might link with
 #   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
 #
-#   If you are only building threads programs, you may wish to use these
+#   If you are only building threaded programs, you may wish to use these
 #   variables in your default LIBS, CFLAGS, and CC:
 #
 #     LIBS="$PTHREAD_LIBS $LIBS"
@@ -30,8 +30,8 @@
 #     CC="$PTHREAD_CC"
 #
 #   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
-#   has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to that name
+#   has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
-#   (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
+#   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
@@ -82,35 +82,40 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 21
+#serial 22
 
 AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
 AC_DEFUN([AX_PTHREAD], [
 AC_REQUIRE([AC_CANONICAL_HOST])
+AC_REQUIRE([AC_PROG_CC])
+AC_REQUIRE([AC_PROG_SED])
 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).
+# requires special compiler flags (e.g. on Tru64 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
+if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
-        save_CFLAGS="$CFLAGS"
+	ax_pthread_save_CC="$CC"
+	ax_pthread_save_CFLAGS="$CFLAGS"
+	ax_pthread_save_LIBS="$LIBS"
+	AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
 	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_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
-        AC_TRY_LINK_FUNC([pthread_join], [ax_pthread_ok=yes])
+	AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
 	AC_MSG_RESULT([$ax_pthread_ok])
-        if test x"$ax_pthread_ok" = xno; then
+	if test "x$ax_pthread_ok" = "xno"; then
 		PTHREAD_LIBS=""
 		PTHREAD_CFLAGS=""
 	fi
-        LIBS="$save_LIBS"
+	CC="$ax_pthread_save_CC"
-        CFLAGS="$save_CFLAGS"
+	CFLAGS="$ax_pthread_save_CFLAGS"
+	LIBS="$ax_pthread_save_LIBS"
 fi
 
 # We must check for the threads library under a number of different
@@ -123,7 +128,7 @@ fi
 # 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"
+ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
 
 # The ordering *is* (sometimes) important.  Some notes on the
 # individual items follow:
@@ -132,82 +137,225 @@ ax_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mt
 # 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)
+# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
-# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
+#           (Note: HP C rejects this with "bad form for `-t' option")
-# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
+# -pthreads: Solaris/gcc (Note: HP C also rejects)
-# -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;
+#      doesn't hurt to check since this sometimes defines pthreads and
-#      also defines -D_REENTRANT)
+#      -D_REENTRANT too), HP C (must be checked before -lpthread, which
-#      ... -mt is also the pthreads flag for HP/aCC
+#      is present but should not be used directly; and before -mthreads,
+#      because the compiler interprets this as "-mt" + "-hreads")
+# -mthreads: Mingw32/gcc, Lynx/gcc
 # pthread: Linux, etcetera
 # --thread-safe: KAI C++
 # pthread-config: use pthread-config program (for GNU Pth library)
 
-case ${host_os} in
+case $host_os in
+
+	freebsd*)
+
+	# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
+	# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
+
+	ax_pthread_flags="-kthread lthread $ax_pthread_flags"
+	;;
+
+	hpux*)
+
+	# From the cc(1) man page: "[-mt] Sets various -D flags to enable
+	# multi-threading and also sets -lpthread."
+
+	ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
+	;;
+
+	openedition*)
+
+	# IBM z/OS requires a feature-test macro to be defined in order to
+	# enable POSIX threads at all, so give the user a hint if this is
+	# not set. (We don't define these ourselves, as they can affect
+	# other portions of the system API in unpredictable ways.)
+
+	AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
+	    [
+#	     if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
+	     AX_PTHREAD_ZOS_MISSING
+#	     endif
+	    ],
+	    [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
+	;;
+
 	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/
+	# tests will erroneously succeed. (N.B.: The stubs are missing
-        # -lpthread.)  (The stubs are missing pthread_cleanup_push, or rather
+	# pthread_cleanup_push, or rather a function called by this macro,
-        # a function called by this macro, so we could check for that, but
+	# so we could check for that, but who knows whether they'll stub
-        # who knows whether they'll stub that too in a future libc.)  So,
+	# that too in a future libc.)  So we'll check first for the
-        # we'll just look for -pthreads and -lpthread first:
+	# standard Solaris way of linking pthreads (-mt -lpthread).
 
-        ax_pthread_flags="-pthreads pthread -mt -pthread $ax_pthread_flags"
+	ax_pthread_flags="-mt,pthread pthread $ax_pthread_flags"
-        ;;
-
-        darwin*)
-        ax_pthread_flags="-pthread $ax_pthread_flags"
 	;;
 esac
 
-# Clang doesn't consider unrecognized options an error unless we specify
+# GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
-# -Werror. We throw in some extra Clang-specific options to ensure that
-# this doesn't happen for GCC, which also accepts -Werror.
 
-AC_MSG_CHECKING([if compiler needs -Werror to reject unknown flags])
+AS_IF([test "x$GCC" = "xyes"],
-save_CFLAGS="$CFLAGS"
+      [ax_pthread_flags="-pthread -pthreads $ax_pthread_flags"])
-ax_pthread_extra_flags="-Werror"
-CFLAGS="$CFLAGS $ax_pthread_extra_flags -Wunknown-warning-option -Wsizeof-array-argument"
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([int foo(void);],[foo()])],
-                  [AC_MSG_RESULT([yes])],
-                  [ax_pthread_extra_flags=
-                   AC_MSG_RESULT([no])])
-CFLAGS="$save_CFLAGS"
 
-if test x"$ax_pthread_ok" = xno; then
+# The presence of a feature test macro requesting re-entrant function
-for flag in $ax_pthread_flags; do
+# definitions is, on some systems, a strong hint that pthreads support is
+# correctly enabled
 
-        case $flag in
+case $host_os in
+	darwin* | hpux* | linux* | osf* | solaris*)
+	ax_pthread_check_macro="_REENTRANT"
+	;;
+
+	aix* | freebsd*)
+	ax_pthread_check_macro="_THREAD_SAFE"
+	;;
+
+	*)
+	ax_pthread_check_macro="--"
+	;;
+esac
+AS_IF([test "x$ax_pthread_check_macro" = "x--"],
+      [ax_pthread_check_cond=0],
+      [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
+
+# Are we compiling with Clang?
+
+AC_CACHE_CHECK([whether $CC is Clang],
+    [ax_cv_PTHREAD_CLANG],
+    [ax_cv_PTHREAD_CLANG=no
+     # Note that Autoconf sets GCC=yes for Clang as well as GCC
+     if test "x$GCC" = "xyes"; then
+	AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
+	    [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
+#	     if defined(__clang__) && defined(__llvm__)
+	     AX_PTHREAD_CC_IS_CLANG
+#	     endif
+	    ],
+	    [ax_cv_PTHREAD_CLANG=yes])
+     fi
+    ])
+ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
+
+ax_pthread_clang_warning=no
+
+# Clang needs special handling, because older versions handle the -pthread
+# option in a rather... idiosyncratic way
+
+if test "x$ax_pthread_clang" = "xyes"; then
+
+	# Clang takes -pthread; it has never supported any other flag
+
+	# (Note 1: This will need to be revisited if a system that Clang
+	# supports has POSIX threads in a separate library.  This tends not
+	# to be the way of modern systems, but it's conceivable.)
+
+	# (Note 2: On some systems, notably Darwin, -pthread is not needed
+	# to get POSIX threads support; the API is always present and
+	# active.  We could reasonably leave PTHREAD_CFLAGS empty.  But
+	# -pthread does define _REENTRANT, and while the Darwin headers
+	# ignore this macro, third-party headers might not.)
+
+	PTHREAD_CFLAGS="-pthread"
+	PTHREAD_LIBS=
+
+	ax_pthread_ok=yes
+
+	# However, older versions of Clang make a point of warning the user
+	# that, in an invocation where only linking and no compilation is
+	# taking place, the -pthread option has no effect ("argument unused
+	# during compilation").  They expect -pthread to be passed in only
+	# when source code is being compiled.
+	#
+	# Problem is, this is at odds with the way Automake and most other
+	# C build frameworks function, which is that the same flags used in
+	# compilation (CFLAGS) are also used in linking.  Many systems
+	# supported by AX_PTHREAD require exactly this for POSIX threads
+	# support, and in fact it is often not straightforward to specify a
+	# flag that is used only in the compilation phase and not in
+	# linking.  Such a scenario is extremely rare in practice.
+	#
+	# Even though use of the -pthread flag in linking would only print
+	# a warning, this can be a nuisance for well-run software projects
+	# that build with -Werror.  So if the active version of Clang has
+	# this misfeature, we search for an option to squash it.
+
+	AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
+	    [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
+	    [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
+	     # Create an alternate version of $ac_link that compiles and
+	     # links in two steps (.c -> .o, .o -> exe) instead of one
+	     # (.c -> exe), because the warning occurs only in the second
+	     # step
+	     ax_pthread_save_ac_link="$ac_link"
+	     ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
+	     ax_pthread_link_step=`$as_echo "$ac_link" | sed "$ax_pthread_sed"`
+	     ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
+	     ax_pthread_save_CFLAGS="$CFLAGS"
+	     for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
+		AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
+		CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
+		ac_link="$ax_pthread_save_ac_link"
+		AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+		    [ac_link="$ax_pthread_2step_ac_link"
+		     AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+			 [break])
+		    ])
+	     done
+	     ac_link="$ax_pthread_save_ac_link"
+	     CFLAGS="$ax_pthread_save_CFLAGS"
+	     AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
+	     ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
+	    ])
+
+	case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
+		no | unknown) ;;
+		*) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
+	esac
+
+fi # $ax_pthread_clang = yes
+
+if test "x$ax_pthread_ok" = "xno"; then
+for ax_pthread_try_flag in $ax_pthread_flags; do
+
+	case $ax_pthread_try_flag in
 		none)
 		AC_MSG_CHECKING([whether pthreads work without any flags])
 		;;
 
+		-mt,pthread)
+		AC_MSG_CHECKING([whether pthreads work with -mt -lpthread])
+		PTHREAD_CFLAGS="-mt"
+		PTHREAD_LIBS="-lpthread"
+		;;
+
 		-*)
-                AC_MSG_CHECKING([whether pthreads work with $flag])
+		AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
-                PTHREAD_CFLAGS="$flag"
+		PTHREAD_CFLAGS="$ax_pthread_try_flag"
 		;;
 
 		pthread-config)
 		AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
-                if test x"$ax_pthread_config" = xno; then continue; fi
+		AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
 		PTHREAD_CFLAGS="`pthread-config --cflags`"
 		PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
 		;;
 
 		*)
-                AC_MSG_CHECKING([for the pthreads library -l$flag])
+		AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
-                PTHREAD_LIBS="-l$flag"
+		PTHREAD_LIBS="-l$ax_pthread_try_flag"
 		;;
 	esac
 
-        save_LIBS="$LIBS"
+	ax_pthread_save_CFLAGS="$CFLAGS"
-        save_CFLAGS="$CFLAGS"
+	ax_pthread_save_LIBS="$LIBS"
+	CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
 	LIBS="$PTHREAD_LIBS $LIBS"
-        CFLAGS="$CFLAGS $PTHREAD_CFLAGS $ax_pthread_extra_flags"
 
 	# Check for various functions.  We must include pthread.h,
 	# since some functions may be macros.  (On the Sequent, we
@@ -218,7 +366,11 @@ for flag in $ax_pthread_flags; do
 	# 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>
+#			if $ax_pthread_check_cond
+#			 error "$ax_pthread_check_macro must be defined"
+#			endif
 			static void routine(void *a) { a = 0; }
 			static void *start_routine(void *a) { return a; }],
 		       [pthread_t th; pthread_attr_t attr;
@@ -230,13 +382,11 @@ for flag in $ax_pthread_flags; do
 	    [ax_pthread_ok=yes],
 	    [])
 
-        LIBS="$save_LIBS"
+	CFLAGS="$ax_pthread_save_CFLAGS"
-        CFLAGS="$save_CFLAGS"
+	LIBS="$ax_pthread_save_LIBS"
 
 	AC_MSG_RESULT([$ax_pthread_ok])
-        if test "x$ax_pthread_ok" = xyes; then
+	AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
-                break;
-        fi
 
 	PTHREAD_LIBS=""
 	PTHREAD_CFLAGS=""
@@ -244,62 +394,65 @@ done
 fi
 
 # Various other checks:
-if test "x$ax_pthread_ok" = xyes; then
+if test "x$ax_pthread_ok" = "xyes"; then
-        save_LIBS="$LIBS"
+	ax_pthread_save_CFLAGS="$CFLAGS"
-        LIBS="$PTHREAD_LIBS $LIBS"
+	ax_pthread_save_LIBS="$LIBS"
-        save_CFLAGS="$CFLAGS"
 	CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+	LIBS="$PTHREAD_LIBS $LIBS"
 
 	# Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
-        AC_MSG_CHECKING([for joinable pthread attribute])
+	AC_CACHE_CHECK([for joinable pthread attribute],
-        attr_name=unknown
+	    [ax_cv_PTHREAD_JOINABLE_ATTR],
-        for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
+	    [ax_cv_PTHREAD_JOINABLE_ATTR=unknown
+	     for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
 		 AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
-                           [int attr = $attr; return attr /* ; */])],
+						 [int attr = $ax_pthread_attr; return attr /* ; */])],
-                [attr_name=$attr; break],
+				[ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
 				[])
 	     done
-        AC_MSG_RESULT([$attr_name])
+	    ])
-        if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then
+	AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
-            AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE], [$attr_name],
+	       test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
+	       test "x$ax_pthread_joinable_attr_defined" != "xyes"],
+	      [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
+				  [$ax_cv_PTHREAD_JOINABLE_ATTR],
 				  [Define to necessary symbol if this constant
 				   uses a non-standard name on your system.])
-        fi
+	       ax_pthread_joinable_attr_defined=yes
+	      ])
 
-        AC_MSG_CHECKING([if more special flags are required for pthreads])
+	AC_CACHE_CHECK([whether more special flags are required for pthreads],
-        flag=no
+	    [ax_cv_PTHREAD_SPECIAL_FLAGS],
-        case ${host_os} in
+	    [ax_cv_PTHREAD_SPECIAL_FLAGS=no
-            aix* | freebsd* | darwin*) flag="-D_THREAD_SAFE";;
+	     case $host_os in
-            osf* | hpux*) flag="-D_REENTRANT";;
 	     solaris*)
-            if test "$GCC" = "yes"; then
+	     ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
-                flag="-D_REENTRANT"
-            else
-                # TODO: What about Clang on Solaris?
-                flag="-mt -D_REENTRANT"
-            fi
 	     ;;
 	     esac
-        AC_MSG_RESULT([$flag])
+	    ])
-        if test "x$flag" != xno; then
+	AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
-            PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
+	       test "x$ax_pthread_special_flags_added" != "xyes"],
-        fi
+	      [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
+	       ax_pthread_special_flags_added=yes])
 
 	AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
-            [ax_cv_PTHREAD_PRIO_INHERIT], [
+	    [ax_cv_PTHREAD_PRIO_INHERIT],
-                AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
+	    [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$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes"],
+	AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
-            [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])])
+	       test "x$ax_pthread_prio_inherit_defined" != "xyes"],
+	      [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
+	       ax_pthread_prio_inherit_defined=yes
+	      ])
 
-        LIBS="$save_LIBS"
+	CFLAGS="$ax_pthread_save_CFLAGS"
-        CFLAGS="$save_CFLAGS"
+	LIBS="$ax_pthread_save_LIBS"
 
 	# More AIX lossage: compile with *_r variant
-        if test "x$GCC" != xyes; then
+	if test "x$GCC" != "xyes"; then
 	    case $host_os in
 		aix*)
 		AS_CASE(["x/$CC"],
@@ -321,7 +474,7 @@ AC_SUBST([PTHREAD_CFLAGS])
 AC_SUBST([PTHREAD_CC])
 
 # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
-if test x"$ax_pthread_ok" = xyes; then
+if test "x$ax_pthread_ok" = "xyes"; then
 	ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
 	:
 else