more autoconf fixes- use version of boost m4 macros which are much, much, much better

1 files changed, 1035 insertions, 0 deletions

diff --git a/m4/boost.m4 b/m4/boost.m4
new file mode 100644
index 00000000..7e0ed075
--- /dev/null
+++ b/m4/boost.m4
@@ -0,0 +1,1035 @@
+# boost.m4: Locate Boost headers and libraries for autoconf-based projects.
+# Copyright (C) 2007, 2008, 2009  Benoit Sigoure <tsuna@lrde.epita.fr>
+#
+# 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.
+#
+# Additional permission under section 7 of the GNU General Public
+# License, version 3 ("GPLv3"):
+#
+# If you convey this file as part of a work that contains a
+# configuration script generated by Autoconf, you may do so under
+# terms of your choice.
+#
+# 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/>.
+
+m4_define([_BOOST_SERIAL], [m4_translit([
+# serial 12
+], [#
+], [])])
+
+# Original sources can be found at http://github.com/tsuna/boost.m4
+# You can fetch the latest version of the script by doing:
+#   wget http://github.com/tsuna/boost.m4/raw/master/build-aux/boost.m4
+
+# ------ #
+# README #
+# ------ #
+
+# This file provides several macros to use the various Boost libraries.
+# The first macro is BOOST_REQUIRE.  It will simply check if it's possible to
+# find the Boost headers of a given (optional) minimum version and it will
+# define BOOST_CPPFLAGS accordingly.  It will add an option --with-boost to
+# your configure so that users can specify non standard locations.
+# If the user's environment contains BOOST_ROOT and --with-boost was not
+# specified, --with-boost=$BOOST_ROOT is implicitly used.
+# For more README and documentation, go to http://github.com/tsuna/boost.m4
+# Note: THESE MACROS ASSUME THAT YOU USE LIBTOOL.  If you don't, don't worry,
+# simply read the README, it will show you what to do step by step.
+
+m4_pattern_forbid([^_?BOOST_])
+
+
+# _BOOST_SED_CPP(SED-PROGRAM, PROGRAM,
+#                [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
+# --------------------------------------------------------
+# Same as AC_EGREP_CPP, but leave the result in conftest.i.
+# PATTERN is *not* overquoted, as in AC_EGREP_CPP.  It could be useful
+# to turn this into a macro which extracts the value of any macro.
+m4_define([_BOOST_SED_CPP],
+[AC_LANG_PREPROC_REQUIRE()dnl
+AC_REQUIRE([AC_PROG_SED])dnl
+AC_LANG_CONFTEST([AC_LANG_SOURCE([[$2]])])
+AS_IF([dnl eval is necessary to expand ac_cpp.
+dnl Ultrix and Pyramid sh refuse to redirect output of eval, so use subshell.
+dnl Beware of Windows end-of-lines, for instance if we are running
+dnl some Windows programs under Wine.  In that case, boost/version.hpp
+dnl is certainly using "\r\n", but the regular Unix shell will only
+dnl strip `\n' with backquotes, not the `\r'.  This results in
+dnl boost_cv_lib_version='1_37\r' for instance, which breaks
+dnl everything else.
+dnl Cannot use 'dnl' after [$4] because a trailing dnl may break AC_CACHE_CHECK
+(eval "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
+  tr -d '\r' |
+  $SED -n -e "$1" >conftest.i 2>&1],
+  [$3],
+  [$4])
+rm -rf conftest*
+])# AC_EGREP_CPP
+
+
+
+# BOOST_REQUIRE([VERSION], [ACTION-IF-NOT-FOUND])
+# -----------------------------------------------
+# Look for Boost.  If version is given, it must either be a literal of the form
+# "X.Y.Z" where X, Y and Z are integers (the ".Z" part being optional) or a
+# variable "$var".
+# Defines the value BOOST_CPPFLAGS.  This macro only checks for headers with
+# the required version, it does not check for any of the Boost libraries.
+# On # success, defines HAVE_BOOST.  On failure, calls the optional
+# ACTION-IF-NOT-FOUND action if one was supplied.
+# Otherwise aborts with an error message.
+AC_DEFUN([BOOST_REQUIRE],
+[AC_REQUIRE([AC_PROG_CXX])dnl
+AC_REQUIRE([AC_PROG_GREP])dnl
+echo "$as_me: this is boost.m4[]_BOOST_SERIAL" >&AS_MESSAGE_LOG_FD
+boost_save_IFS=$IFS
+boost_version_req=$1
+IFS=.
+set x $boost_version_req 0 0 0
+IFS=$boost_save_IFS
+shift
+boost_version_req=`expr "$[1]" '*' 100000 + "$[2]" '*' 100 + "$[3]"`
+AC_ARG_WITH([boost],
+   [AS_HELP_STRING([--with-boost=DIR],
+                   [prefix of Boost $1 @<:@guess@:>@])])dnl
+AC_ARG_VAR([BOOST_ROOT],[Location of Boost installation])dnl
+# If BOOST_ROOT is set and the user has not provided a value to
+# --with-boost, then treat BOOST_ROOT as if it the user supplied it.
+if test x"$BOOST_ROOT" != x; then
+  if test x"$with_boost" = x; then
+    AC_MSG_NOTICE([Detected BOOST_ROOT; continuing with --with-boost=$BOOST_ROOT])
+    with_boost=$BOOST_ROOT
+  else
+    AC_MSG_NOTICE([Detected BOOST_ROOT=$BOOST_ROOT, but overridden by --with-boost=$with_boost])
+  fi
+fi
+AC_SUBST([DISTCHECK_CONFIGURE_FLAGS],
+         ["$DISTCHECK_CONFIGURE_FLAGS '--with-boost=$with_boost'"])
+boost_save_CPPFLAGS=$CPPFLAGS
+  AC_CACHE_CHECK([for Boost headers version >= $boost_version_req],
+    [boost_cv_inc_path],
+    [boost_cv_inc_path=no
+AC_LANG_PUSH([C++])dnl
+m4_pattern_allow([^BOOST_VERSION$])dnl
+    AC_LANG_CONFTEST([AC_LANG_PROGRAM([[#include <boost/version.hpp>
+#if !defined BOOST_VERSION
+# error BOOST_VERSION is not defined
+#elif BOOST_VERSION < $boost_version_req
+# error Boost headers version < $boost_version_req
+#endif
+]])])
+    # If the user provided a value to --with-boost, use it and only it.
+    case $with_boost in #(
+      ''|yes) set x '' /opt/local/include /usr/local/include /opt/include \
+                 /usr/include C:/Boost/include;; #(
+      *)      set x "$with_boost/include" "$with_boost";;
+    esac
+    shift
+    for boost_dir
+    do
+    # Without --layout=system, Boost (or at least some versions) installs
+    # itself in <prefix>/include/boost-<version>.  This inner loop helps to
+    # find headers in such directories.
+    #
+    # Any ${boost_dir}/boost-x_xx directories are searched in reverse version
+    # order followed by ${boost_dir}.  The final '.' is a sentinel for
+    # searching $boost_dir" itself.  Entries are whitespace separated.
+    #
+    # I didn't indent this loop on purpose (to avoid over-indented code)
+    boost_layout_system_search_list=`cd "$boost_dir" 2>/dev/null \
+        && ls -1 | "${GREP}" '^boost-' | sort -rn -t- -k2 \
+        && echo .`
+    for boost_inc in $boost_layout_system_search_list
+    do
+      if test x"$boost_inc" != x.; then
+        boost_inc="$boost_dir/$boost_inc"
+      else
+        boost_inc="$boost_dir" # Uses sentinel in boost_layout_system_search_list
+      fi
+      if test x"$boost_inc" != x; then
+        # We are going to check whether the version of Boost installed
+        # in $boost_inc is usable by running a compilation that
+        # #includes it.  But if we pass a -I/some/path in which Boost
+        # is not installed, the compiler will just skip this -I and
+        # use other locations (either from CPPFLAGS, or from its list
+        # of system include directories).  As a result we would use
+        # header installed on the machine instead of the /some/path
+        # specified by the user.  So in that precise case (trying
+        # $boost_inc), make sure the version.hpp exists.
+        #
+        # Use test -e as there can be symlinks.
+        test -e "$boost_inc/boost/version.hpp" || continue
+        CPPFLAGS="$CPPFLAGS -I$boost_inc"
+      fi
+      AC_COMPILE_IFELSE([], [boost_cv_inc_path=yes], [boost_cv_version=no])
+      if test x"$boost_cv_inc_path" = xyes; then
+        if test x"$boost_inc" != x; then
+          boost_cv_inc_path=$boost_inc
+        fi
+        break 2
+      fi
+    done
+    done
+AC_LANG_POP([C++])dnl
+    ])
+    case $boost_cv_inc_path in #(
+      no)
+        boost_errmsg="cannot find Boost headers version >= $boost_version_req"
+        m4_if([$2], [],  [AC_MSG_ERROR([$boost_errmsg])],
+                        [AC_MSG_NOTICE([$boost_errmsg])])
+        $2
+        ;;#(
+      yes)
+        BOOST_CPPFLAGS=
+        AC_DEFINE([HAVE_BOOST], [1],
+                  [Defined if the requested minimum BOOST version is satisfied])
+        ;;#(
+      *)
+        AC_SUBST([BOOST_CPPFLAGS], ["-I$boost_cv_inc_path"])
+        ;;
+    esac
+  AC_CACHE_CHECK([for Boost's header version],
+    [boost_cv_lib_version],
+    [m4_pattern_allow([^BOOST_LIB_VERSION$])dnl
+     _BOOST_SED_CPP([/^boost-lib-version = /{s///;s/\"//g;p;g;}],
+                    [#include <boost/version.hpp>
+boost-lib-version = BOOST_LIB_VERSION],
+    [boost_cv_lib_version=`cat conftest.i`])])
+    # e.g. "134" for 1_34_1 or "135" for 1_35
+    boost_major_version=`echo "$boost_cv_lib_version" | sed 's/_//;s/_.*//'`
+    case $boost_major_version in #(
+      '' | *[[!0-9]]*)
+        AC_MSG_ERROR([invalid value: boost_major_version=$boost_major_version])
+        ;;
+    esac
+CPPFLAGS=$boost_save_CPPFLAGS
+])# BOOST_REQUIRE
+
+# BOOST_STATIC()
+# --------------
+# Add the "--enable-static-boost" configure argument. If this argument is given
+# on the command line, static versions of the libraries will be looked up.
+AC_DEFUN([BOOST_STATIC],
+  [AC_ARG_ENABLE([static-boost],
+     [AC_HELP_STRING([--enable-static-boost],
+               [Prefer the static boost libraries over the shared ones [no]])],
+     [enable_static_boost=yes],
+     [enable_static_boost=no])])# BOOST_STATIC
+
+# BOOST_FIND_HEADER([HEADER-NAME], [ACTION-IF-NOT-FOUND], [ACTION-IF-FOUND])
+# --------------------------------------------------------------------------
+# Wrapper around AC_CHECK_HEADER for Boost headers.  Useful to check for
+# some parts of the Boost library which are only made of headers and don't
+# require linking (such as Boost.Foreach).
+#
+# Default ACTION-IF-NOT-FOUND: Fail with a fatal error unless Boost couldn't be
+# found in the first place, in which case by default a notice is issued to the
+# user.  Presumably if we haven't died already it's because it's OK to not have
+# Boost, which is why only a notice is issued instead of a hard error.
+#
+# Default ACTION-IF-FOUND: define the preprocessor symbol HAVE_<HEADER-NAME> in
+# case of success # (where HEADER-NAME is written LIKE_THIS, e.g.,
+# HAVE_BOOST_FOREACH_HPP).
+AC_DEFUN([BOOST_FIND_HEADER],
+[AC_REQUIRE([BOOST_REQUIRE])dnl
+if test x"$boost_cv_inc_path" = xno; then
+  m4_default([$2], [AC_MSG_NOTICE([Boost not available, not searching for $1])])
+else
+AC_LANG_PUSH([C++])dnl
+boost_save_CPPFLAGS=$CPPFLAGS
+CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
+AC_CHECK_HEADER([$1],
+  [m4_default([$3], [AC_DEFINE(AS_TR_CPP([HAVE_$1]), [1],
+                               [Define to 1 if you have <$1>])])],
+  [m4_default([$2], [AC_MSG_ERROR([cannot find $1])])])
+CPPFLAGS=$boost_save_CPPFLAGS
+AC_LANG_POP([C++])dnl
+fi
+])# BOOST_FIND_HEADER
+
+
+# BOOST_FIND_LIB([LIB-NAME], [PREFERRED-RT-OPT], [HEADER-NAME], [CXX-TEST],
+#                [CXX-PROLOGUE])
+# -------------------------------------------------------------------------
+# Look for the Boost library LIB-NAME (e.g., LIB-NAME = `thread', for
+# libboost_thread).  Check that HEADER-NAME works and check that
+# libboost_LIB-NAME can link with the code CXX-TEST.  The optional argument
+# CXX-PROLOGUE can be used to include some C++ code before the `main'
+# function.
+#
+# Invokes BOOST_FIND_HEADER([HEADER-NAME]) (see above).
+#
+# Boost libraries typically come compiled with several flavors (with different
+# runtime options) so PREFERRED-RT-OPT is the preferred suffix.  A suffix is one
+# or more of the following letters: sgdpn (in that order).  s = static
+# runtime, d = debug build, g = debug/diagnostic runtime, p = STLPort build,
+# n = (unsure) STLPort build without iostreams from STLPort (it looks like `n'
+# must always be used along with `p').  Additionally, PREFERRED-RT-OPT can
+# start with `mt-' to indicate that there is a preference for multi-thread
+# builds.  Some sample values for PREFERRED-RT-OPT: (nothing), mt, d, mt-d, gdp
+# ...  If you want to make sure you have a specific version of Boost
+# (eg, >= 1.33) you *must* invoke BOOST_REQUIRE before this macro.
+AC_DEFUN([BOOST_FIND_LIB],
+[AC_REQUIRE([BOOST_REQUIRE])dnl
+AC_REQUIRE([_BOOST_FIND_COMPILER_TAG])dnl
+AC_REQUIRE([BOOST_STATIC])dnl
+AC_REQUIRE([_BOOST_GUESS_WHETHER_TO_USE_MT])dnl
+if test x"$boost_cv_inc_path" = xno; then
+  AC_MSG_NOTICE([Boost not available, not searching for the Boost $1 library])
+else
+dnl The else branch is huge and wasn't intended on purpose.
+AC_LANG_PUSH([C++])dnl
+AS_VAR_PUSHDEF([Boost_lib], [boost_cv_lib_$1])dnl
+AS_VAR_PUSHDEF([Boost_lib_LDFLAGS], [boost_cv_lib_$1_LDFLAGS])dnl
+AS_VAR_PUSHDEF([Boost_lib_LIBS], [boost_cv_lib_$1_LIBS])dnl
+BOOST_FIND_HEADER([$3])
+boost_save_CPPFLAGS=$CPPFLAGS
+CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
+# Now let's try to find the library.  The algorithm is as follows: first look
+# for a given library name according to the user's PREFERRED-RT-OPT.  For each
+# library name, we prefer to use the ones that carry the tag (toolset name).
+# Each library is searched through the various standard paths were Boost is
+# usually installed.  If we can't find the standard variants, we try to
+# enforce -mt (for instance on MacOSX, libboost_threads.dylib doesn't exist
+# but there's -obviously- libboost_threads-mt.dylib).
+AC_CACHE_CHECK([for the Boost $1 library], [Boost_lib],
+  [Boost_lib=no
+  case "$2" in #(
+    mt | mt-) boost_mt=-mt; boost_rtopt=;; #(
+    mt* | mt-*) boost_mt=-mt; boost_rtopt=`expr "X$2" : 'Xmt-*\(.*\)'`;; #(
+    *) boost_mt=; boost_rtopt=$2;;
+  esac
+  if test $enable_static_boost = yes; then
+    boost_rtopt="s$boost_rtopt"
+  fi
+  # Find the proper debug variant depending on what we've been asked to find.
+  case $boost_rtopt in #(
+    *d*) boost_rt_d=$boost_rtopt;; #(
+    *[[sgpn]]*) # Insert the `d' at the right place (in between `sg' and `pn')
+      boost_rt_d=`echo "$boost_rtopt" | sed 's/\(s*g*\)\(p*n*\)/\1\2/'`;; #(
+    *) boost_rt_d='-d';;
+  esac
+  # If the PREFERRED-RT-OPT are not empty, prepend a `-'.
+  test -n "$boost_rtopt" && boost_rtopt="-$boost_rtopt"
+  $boost_guess_use_mt && boost_mt=-mt
+  # Look for the abs path the static archive.
+  # $libext is computed by Libtool but let's make sure it's non empty.
+  test -z "$libext" &&
+    AC_MSG_ERROR([the libext variable is empty, did you invoke Libtool?])
+  boost_save_ac_objext=$ac_objext
+  # Generate the test file.
+  AC_LANG_CONFTEST([AC_LANG_PROGRAM([#include <$3>
+$5], [$4])])
+dnl Optimization hacks: compiling C++ is slow, especially with Boost.  What
+dnl we're trying to do here is guess the right combination of link flags
+dnl (LIBS / LDFLAGS) to use a given library.  This can take several
+dnl iterations before it succeeds and is thus *very* slow.  So what we do
+dnl instead is that we compile the code first (and thus get an object file,
+dnl typically conftest.o).  Then we try various combinations of link flags
+dnl until we succeed to link conftest.o in an executable.  The problem is
+dnl that the various TRY_LINK / COMPILE_IFELSE macros of Autoconf always
+dnl remove all the temporary files including conftest.o.  So the trick here
+dnl is to temporarily change the value of ac_objext so that conftest.o is
+dnl preserved accross tests.  This is obviously fragile and I will burn in
+dnl hell for not respecting Autoconf's documented interfaces, but in the
+dnl mean time, it optimizes the macro by a factor of 5 to 30.
+dnl Another small optimization: the first argument of AC_COMPILE_IFELSE left
+dnl empty because the test file is generated only once above (before we
+dnl start the for loops).
+  AC_COMPILE_IFELSE([],
+    [ac_objext=do_not_rm_me_plz],
+    [AC_MSG_ERROR([cannot compile a test that uses Boost $1])])
+  ac_objext=$boost_save_ac_objext
+  boost_failed_libs=
+# Don't bother to ident the 6 nested for loops, only the 2 innermost ones
+# matter.
+for boost_tag_ in -$boost_cv_lib_tag ''; do
+for boost_ver_ in -$boost_cv_lib_version ''; do
+for boost_mt_ in $boost_mt -mt ''; do
+for boost_rtopt_ in $boost_rtopt '' -d; do
+  for boost_lib in \
+    boost_$1$boost_tag_$boost_mt_$boost_rtopt_$boost_ver_ \
+    boost_$1$boost_tag_$boost_rtopt_$boost_ver_ \
+    boost_$1$boost_tag_$boost_mt_$boost_ver_ \
+    boost_$1$boost_tag_$boost_ver_
+  do
+    # Avoid testing twice the same lib
+    case $boost_failed_libs in #(
+      *@$boost_lib@*) continue;;
+    esac
+    # If with_boost is empty, we'll search in /lib first, which is not quite
+    # right so instead we'll try to a location based on where the headers are.
+    boost_tmp_lib=$with_boost
+    test x"$with_boost" = x && boost_tmp_lib=${boost_cv_inc_path%/include}
+    for boost_ldpath in "$boost_tmp_lib/lib" '' \
+             /opt/local/lib /usr/local/lib /opt/lib /usr/lib \
+             "$with_boost" C:/Boost/lib /lib /usr/lib64 /lib64
+    do
+      test -e "$boost_ldpath" || continue
+      boost_save_LDFLAGS=$LDFLAGS
+      # Are we looking for a static library?
+      case $boost_ldpath:$boost_rtopt_ in #(
+        *?*:*s*) # Yes (Non empty boost_ldpath + s in rt opt)
+          Boost_lib_LIBS="$boost_ldpath/lib$boost_lib.$libext"
+          test -e "$Boost_lib_LIBS" || continue;; #(
+        *) # No: use -lboost_foo to find the shared library.
+          Boost_lib_LIBS="-l$boost_lib";;
+      esac
+      boost_save_LIBS=$LIBS
+      LIBS="$Boost_lib_LIBS $LIBS"
+      test x"$boost_ldpath" != x && LDFLAGS="$LDFLAGS -L$boost_ldpath"
+dnl First argument of AC_LINK_IFELSE left empty because the test file is
+dnl generated only once above (before we start the for loops).
+      _BOOST_AC_LINK_IFELSE([],
+                            [Boost_lib=yes], [Boost_lib=no])
+      ac_objext=$boost_save_ac_objext
+      LDFLAGS=$boost_save_LDFLAGS
+      LIBS=$boost_save_LIBS
+      if test x"$Boost_lib" = xyes; then
+        Boost_lib_LDFLAGS="-L$boost_ldpath -R$boost_ldpath"
+        break 6
+      else
+        boost_failed_libs="$boost_failed_libs@$boost_lib@"
+      fi
+    done
+  done
+done
+done
+done
+done
+rm -f conftest.$ac_objext
+])
+case $Boost_lib in #(
+  no) _AC_MSG_LOG_CONFTEST
+    AC_MSG_ERROR([cannot not find the flags to link with Boost $1])
+    ;;
+esac
+AC_SUBST(AS_TR_CPP([BOOST_$1_LDFLAGS]), [$Boost_lib_LDFLAGS])
+AC_SUBST(AS_TR_CPP([BOOST_$1_LIBS]), [$Boost_lib_LIBS])
+CPPFLAGS=$boost_save_CPPFLAGS
+AS_VAR_POPDEF([Boost_lib])dnl
+AS_VAR_POPDEF([Boost_lib_LDFLAGS])dnl
+AS_VAR_POPDEF([Boost_lib_LIBS])dnl
+AC_LANG_POP([C++])dnl
+fi
+])# BOOST_FIND_LIB
+
+
+# --------------------------------------- #
+# Checks for the various Boost libraries. #
+# --------------------------------------- #
+
+# List of boost libraries: http://www.boost.org/libs/libraries.htm
+# The page http://beta.boost.org/doc/libs is useful: it gives the first release
+# version of each library (among other things).
+
+# BOOST_ARRAY()
+# -------------
+# Look for Boost.Array
+AC_DEFUN([BOOST_ARRAY],
+[BOOST_FIND_HEADER([boost/array.hpp])])
+
+
+# BOOST_ASIO()
+# ------------
+# Look for Boost.Asio (new in Boost 1.35).
+AC_DEFUN([BOOST_ASIO],
+[AC_REQUIRE([BOOST_SYSTEM])dnl
+BOOST_FIND_HEADER([boost/asio.hpp])])
+
+
+# BOOST_BIND()
+# ------------
+# Look for Boost.Bind
+AC_DEFUN([BOOST_BIND],
+[BOOST_FIND_HEADER([boost/bind.hpp])])
+
+
+# BOOST_CONVERSION()
+# ------------------
+# Look for Boost.Conversion (cast / lexical_cast)
+AC_DEFUN([BOOST_CONVERSION],
+[BOOST_FIND_HEADER([boost/cast.hpp])
+BOOST_FIND_HEADER([boost/lexical_cast.hpp])
+])# BOOST_CONVERSION
+
+
+# BOOST_DATE_TIME([PREFERRED-RT-OPT])
+# -----------------------------------
+# Look for Boost.Date_Time.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_DATE_TIME],
+[BOOST_FIND_LIB([date_time], [$1],
+                [boost/date_time/posix_time/posix_time.hpp],
+                [boost::posix_time::ptime t;])
+])# BOOST_DATE_TIME
+
+
+# BOOST_FILESYSTEM([PREFERRED-RT-OPT])
+# ------------------------------------
+# Look for Boost.Filesystem.  For the documentation of PREFERRED-RT-OPT, see
+# the documentation of BOOST_FIND_LIB above.
+# Do not check for boost/filesystem.hpp because this file was introduced in
+# 1.34.
+AC_DEFUN([BOOST_FILESYSTEM],
+[# Do we have to check for Boost.System?  This link-time dependency was
+# added as of 1.35.0.  If we have a version <1.35, we must not attempt to
+# find Boost.System as it didn't exist by then.
+if test $boost_major_version -ge 135; then
+BOOST_SYSTEM([$1])
+fi # end of the Boost.System check.
+boost_filesystem_save_LIBS=$LIBS
+boost_filesystem_save_LDFLAGS=$LDFLAGS
+m4_pattern_allow([^BOOST_SYSTEM_(LIBS|LDFLAGS)$])dnl
+LIBS="$LIBS $BOOST_SYSTEM_LIBS"
+LDFLAGS="$LDFLAGS $BOOST_SYSTEM_LDFLAGS"
+BOOST_FIND_LIB([filesystem], [$1],
+                [boost/filesystem/path.hpp], [boost::filesystem::path p;])
+LIBS=$boost_filesystem_save_LIBS
+LDFLAGS=$boost_filesystem_save_LDFLAGS
+])# BOOST_FILESYSTEM
+
+
+# BOOST_FOREACH()
+# ---------------
+# Look for Boost.Foreach
+AC_DEFUN([BOOST_FOREACH],
+[BOOST_FIND_HEADER([boost/foreach.hpp])])
+
+
+# BOOST_FORMAT()
+# --------------
+# Look for Boost.Format
+# Note: we can't check for boost/format/format_fwd.hpp because the header isn't
+# standalone.  It can't be compiled because it triggers the following error:
+# boost/format/detail/config_macros.hpp:88: error: 'locale' in namespace 'std'
+#                                                  does not name a type
+AC_DEFUN([BOOST_FORMAT],
+[BOOST_FIND_HEADER([boost/format.hpp])])
+
+
+# BOOST_FUNCTION()
+# ----------------
+# Look for Boost.Function
+AC_DEFUN([BOOST_FUNCTION],
+[BOOST_FIND_HEADER([boost/function.hpp])])
+
+
+# BOOST_GRAPH([PREFERRED-RT-OPT])
+# -------------------------------
+# Look for Boost.Graphs.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_GRAPH],
+[BOOST_FIND_LIB([graph], [$1],
+                [boost/graph/adjacency_list.hpp], [boost::adjacency_list<> g;])
+])# BOOST_GRAPH
+
+
+# BOOST_IOSTREAMS([PREFERRED-RT-OPT])
+# -------------------------------
+# Look for Boost.IOStreams.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_IOSTREAMS],
+[BOOST_FIND_LIB([iostreams], [$1],
+                [boost/iostreams/device/file_descriptor.hpp],
+                [boost::iostreams::file_descriptor fd(0); fd.close();])
+])# BOOST_IOSTREAMS
+
+
+# BOOST_HASH()
+# ------------
+# Look for Boost.Functional/Hash
+AC_DEFUN([BOOST_HASH],
+[BOOST_FIND_HEADER([boost/functional/hash.hpp])])
+
+
+# BOOST_LAMBDA()
+# --------------
+# Look for Boost.Lambda
+AC_DEFUN([BOOST_LAMBDA],
+[BOOST_FIND_HEADER([boost/lambda/lambda.hpp])])
+
+
+# BOOST_MATH()
+# ------------
+# Look for Boost.Math
+# TODO: This library isn't header-only but it comes in multiple different
+# flavors that don't play well with BOOST_FIND_LIB (e.g, libboost_math_c99,
+# libboost_math_c99f, libboost_math_c99l, libboost_math_tr1,
+# libboost_math_tr1f, libboost_math_tr1l).  This macro must be fixed to do the
+# right thing anyway.
+AC_DEFUN([BOOST_MATH],
+[BOOST_FIND_HEADER([boost/math/special_functions.hpp])])
+
+
+# BOOST_MULTIARRAY()
+# ------------------
+# Look for Boost.MultiArray
+AC_DEFUN([BOOST_MULTIARRAY],
+[BOOST_FIND_HEADER([boost/multi_array.hpp])])
+
+
+# BOOST_NUMERIC_CONVERSION()
+# --------------------------
+# Look for Boost.NumericConversion (policy-based numeric conversion)
+AC_DEFUN([BOOST_NUMERIC_CONVERSION],
+[BOOST_FIND_HEADER([boost/numeric/conversion/converter.hpp])
+])# BOOST_NUMERIC_CONVERSION
+
+
+# BOOST_OPTIONAL()
+# ----------------
+# Look for Boost.Optional
+AC_DEFUN([BOOST_OPTIONAL],
+[BOOST_FIND_HEADER([boost/optional.hpp])])
+
+
+# BOOST_PREPROCESSOR()
+# --------------------
+# Look for Boost.Preprocessor
+AC_DEFUN([BOOST_PREPROCESSOR],
+[BOOST_FIND_HEADER([boost/preprocessor/repeat.hpp])])
+
+
+# BOOST_PROGRAM_OPTIONS([PREFERRED-RT-OPT])
+# -----------------------------------------
+# Look for Boost.Program_options.  For the documentation of PREFERRED-RT-OPT, see
+# the documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_PROGRAM_OPTIONS],
+[BOOST_FIND_LIB([program_options], [$1],
+                [boost/program_options.hpp],
+                [boost::program_options::options_description d("test");])
+])# BOOST_PROGRAM_OPTIONS
+
+
+# BOOST_REF()
+# -----------
+# Look for Boost.Ref
+AC_DEFUN([BOOST_REF],
+[BOOST_FIND_HEADER([boost/ref.hpp])])
+
+
+# BOOST_REGEX([PREFERRED-RT-OPT])
+# -------------------------------
+# Look for Boost.Regex.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_REGEX],
+[BOOST_FIND_LIB([regex], [$1],
+                [boost/regex.hpp],
+                [boost::regex exp("*"); boost::regex_match("foo", exp);])
+])# BOOST_REGEX
+
+
+# BOOST_SERIALIZATION([PREFERRED-RT-OPT])
+# ---------------------------------------
+# Look for Boost.Serialization.  For the documentation of PREFERRED-RT-OPT, see
+# the documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_SERIALIZATION],
+[BOOST_FIND_LIB([serialization], [$1],
+                [boost/archive/text_oarchive.hpp],
+                [std::ostream* o = 0; // Cheap way to get an ostream...
+                boost::archive::text_oarchive t(*o);])
+])# BOOST_SIGNALS
+
+
+# BOOST_SIGNALS([PREFERRED-RT-OPT])
+# ---------------------------------
+# Look for Boost.Signals.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_SIGNALS],
+[BOOST_FIND_LIB([signals], [$1],
+                [boost/signal.hpp],
+                [boost::signal<void ()> s;])
+])# BOOST_SIGNALS
+
+
+# BOOST_SMART_PTR()
+# -----------------
+# Look for Boost.SmartPtr
+AC_DEFUN([BOOST_SMART_PTR],
+[BOOST_FIND_HEADER([boost/scoped_ptr.hpp])
+BOOST_FIND_HEADER([boost/shared_ptr.hpp])
+])
+
+
+# BOOST_STATICASSERT()
+# --------------------
+# Look for Boost.StaticAssert
+AC_DEFUN([BOOST_STATICASSERT],
+[BOOST_FIND_HEADER([boost/static_assert.hpp])])
+
+
+# BOOST_STRING_ALGO()
+# -------------------
+# Look for Boost.StringAlgo
+AC_DEFUN([BOOST_STRING_ALGO],
+[BOOST_FIND_HEADER([boost/algorithm/string.hpp])
+])
+
+
+# BOOST_SYSTEM([PREFERRED-RT-OPT])
+# --------------------------------
+# Look for Boost.System.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.  This library was introduced in Boost
+# 1.35.0.
+AC_DEFUN([BOOST_SYSTEM],
+[BOOST_FIND_LIB([system], [$1],
+                [boost/system/error_code.hpp],
+                [boost::system::error_code e; e.clear();])
+])# BOOST_SYSTEM
+
+
+# BOOST_TEST([PREFERRED-RT-OPT])
+# ------------------------------
+# Look for Boost.Test.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_TEST],
+[m4_pattern_allow([^BOOST_CHECK$])dnl
+BOOST_FIND_LIB([unit_test_framework], [$1],
+               [boost/test/unit_test.hpp], [BOOST_CHECK(2 == 2);],
+               [using boost::unit_test::test_suite;
+               test_suite* init_unit_test_suite(int argc, char ** argv)
+               { return NULL; }])
+])# BOOST_TEST
+
+
+# BOOST_THREADS([PREFERRED-RT-OPT])
+# ---------------------------------
+# Look for Boost.Thread.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+# FIXME: Provide an alias "BOOST_THREAD".
+AC_DEFUN([BOOST_THREADS],
+[dnl Having the pthread flag is required at least on GCC3 where
+dnl boost/thread.hpp would complain if we try to compile without
+dnl -pthread on GNU/Linux.
+AC_REQUIRE([_BOOST_PTHREAD_FLAG])dnl
+boost_threads_save_LIBS=$LIBS
+boost_threads_save_CPPFLAGS=$CPPFLAGS
+LIBS="$LIBS $boost_cv_pthread_flag"
+# Yes, we *need* to put the -pthread thing in CPPFLAGS because with GCC3,
+# boost/thread.hpp will trigger a #error if -pthread isn't used:
+#   boost/config/requires_threads.hpp:47:5: #error "Compiler threading support
+#   is not turned on. Please set the correct command line options for
+#   threading: -pthread (Linux), -pthreads (Solaris) or -mthreads (Mingw32)"
+CPPFLAGS="$CPPFLAGS $boost_cv_pthread_flag"
+BOOST_FIND_LIB([thread], [$1],
+                [boost/thread.hpp], [boost::thread t; boost::mutex m;])
+BOOST_THREAD_LIBS="$BOOST_THREAD_LIBS $boost_cv_pthread_flag"
+BOOST_CPPFLAGS="$BOOST_CPPFLAGS $boost_cv_pthread_flag"
+LIBS=$boost_threads_save_LIBS
+CPPFLAGS=$boost_threads_save_CPPFLAGS
+])# BOOST_THREADS
+
+
+# BOOST_TOKENIZER()
+# -----------------
+# Look for Boost.Tokenizer
+AC_DEFUN([BOOST_TOKENIZER],
+[BOOST_FIND_HEADER([boost/tokenizer.hpp])])
+
+
+# BOOST_TRIBOOL()
+# ---------------
+# Look for Boost.Tribool
+AC_DEFUN([BOOST_TRIBOOL],
+[BOOST_FIND_HEADER([boost/logic/tribool_fwd.hpp])
+BOOST_FIND_HEADER([boost/logic/tribool.hpp])
+])
+
+
+# BOOST_TUPLE()
+# -------------
+# Look for Boost.Tuple
+AC_DEFUN([BOOST_TUPLE],
+[BOOST_FIND_HEADER([boost/tuple/tuple.hpp])])
+
+
+# BOOST_TYPETRAITS()
+# --------------------
+# Look for Boost.TypeTraits
+AC_DEFUN([BOOST_TYPETRAITS],
+[BOOST_FIND_HEADER([boost/type_traits.hpp])])
+
+
+# BOOST_UTILITY()
+# ---------------
+# Look for Boost.Utility (noncopyable, result_of, base-from-member idiom,
+# etc.)
+AC_DEFUN([BOOST_UTILITY],
+[BOOST_FIND_HEADER([boost/utility.hpp])])
+
+
+# BOOST_VARIANT()
+# ---------------
+# Look for Boost.Variant.
+AC_DEFUN([BOOST_VARIANT],
+[BOOST_FIND_HEADER([boost/variant/variant_fwd.hpp])
+BOOST_FIND_HEADER([boost/variant.hpp])])
+
+
+# BOOST_WAVE([PREFERRED-RT-OPT])
+# ------------------------------
+# NOTE: If you intend to use Wave/Spirit with thread support, make sure you
+# call BOOST_THREADS first.
+# Look for Boost.Wave.  For the documentation of PREFERRED-RT-OPT, see the
+# documentation of BOOST_FIND_LIB above.
+AC_DEFUN([BOOST_WAVE],
+[AC_REQUIRE([BOOST_FILESYSTEM])dnl
+AC_REQUIRE([BOOST_DATE_TIME])dnl
+boost_wave_save_LIBS=$LIBS
+boost_wave_save_LDFLAGS=$LDFLAGS
+m4_pattern_allow([^BOOST_((FILE)?SYSTEM|DATE_TIME|THREAD)_(LIBS|LDFLAGS)$])dnl
+LIBS="$LIBS $BOOST_SYSTEM_LIBS $BOOST_FILESYSTEM_LIBS $BOOST_DATE_TIME_LIBS\
+$BOOST_THREAD_LIBS"
+LDFLAGS="$LDFLAGS $BOOST_SYSTEM_LDFLAGS $BOOST_FILESYSTEM_LDFLAGS\
+$BOOST_DATE_TIME_LDFLAGS $BOOST_THREAD_LDFLAGS"
+BOOST_FIND_LIB([wave], [$1],
+                [boost/wave.hpp],
+                [boost::wave::token_id id; get_token_name(id);])
+LIBS=$boost_wave_save_LIBS
+LDFLAGS=$boost_wave_save_LDFLAGS
+])# BOOST_WAVE
+
+
+# BOOST_XPRESSIVE()
+# -----------------
+# Look for Boost.Xpressive (new since 1.36.0).
+AC_DEFUN([BOOST_XPRESSIVE],
+[BOOST_FIND_HEADER([boost/xpressive/xpressive.hpp])])
+
+
+# ----------------- #
+# Internal helpers. #
+# ----------------- #
+
+
+# _BOOST_PTHREAD_FLAG()
+# ---------------------
+# Internal helper for BOOST_THREADS.  Based on ACX_PTHREAD:
+# http://autoconf-archive.cryp.to/acx_pthread.html
+AC_DEFUN([_BOOST_PTHREAD_FLAG],
+[AC_REQUIRE([AC_PROG_CXX])dnl
+AC_REQUIRE([AC_CANONICAL_HOST])dnl
+AC_LANG_PUSH([C++])dnl
+AC_CACHE_CHECK([for the flags needed to use pthreads], [boost_cv_pthread_flag],
+[ boost_cv_pthread_flag=
+  # The ordering *is* (sometimes) important.  Some notes on the
+  # individual items follow:
+  # (none): in case threads are in libc; should be tried before -Kthread and
+  #       other compiler flags to prevent continual compiler warnings
+  # -lpthreads: AIX (must check this before -lpthread)
+  # -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
+  # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
+  # -llthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
+  # -pthread: GNU 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
+  # -lpthread: GNU Linux, etc.
+  # --thread-safe: KAI C++
+  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:
+      boost_pthread_flags="-pthreads -lpthread -mt -pthread";; #(
+    *)
+      boost_pthread_flags="-lpthreads -Kthread -kthread -llthread -pthread \
+                           -pthreads -mthreads -lpthread --thread-safe -mt";;
+  esac
+  # Generate the test file.
+  AC_LANG_CONFTEST([AC_LANG_PROGRAM([#include <pthread.h>],
+    [pthread_t th; pthread_join(th, 0);
+    pthread_attr_init(0); pthread_cleanup_push(0, 0);
+    pthread_create(0,0,0,0); pthread_cleanup_pop(0);])])
+  for boost_pthread_flag in '' $boost_pthread_flags; do
+    boost_pthread_ok=false
+dnl Re-use the test file already generated.
+    boost_pthreads__save_LIBS=$LIBS
+    LIBS="$LIBS $boost_pthread_flag"
+    AC_LINK_IFELSE([],
+      [if grep ".*$boost_pthread_flag" conftest.err; then
+         echo "This flag seems to have triggered warnings" >&AS_MESSAGE_LOG_FD
+       else
+         boost_pthread_ok=:; boost_cv_pthread_flag=$boost_pthread_flag
+       fi])
+    LIBS=$boost_pthreads__save_LIBS
+    $boost_pthread_ok && break
+  done
+])
+AC_LANG_POP([C++])dnl
+])# _BOOST_PTHREAD_FLAG
+
+
+# _BOOST_gcc_test(MAJOR, MINOR)
+# -----------------------------
+# Internal helper for _BOOST_FIND_COMPILER_TAG.
+m4_define([_BOOST_gcc_test],
+["defined __GNUC__ && __GNUC__ == $1 && __GNUC_MINOR__ == $2 && !defined __ICC @ gcc$1$2"])dnl
+
+
+# _BOOST_FIND_COMPILER_TAG()
+# --------------------------
+# Internal.  When Boost is installed without --layout=system, each library
+# filename will hold a suffix that encodes the compiler used during the
+# build.  The Boost build system seems to call this a `tag'.
+AC_DEFUN([_BOOST_FIND_COMPILER_TAG],
+[AC_REQUIRE([AC_PROG_CXX])dnl
+AC_REQUIRE([AC_CANONICAL_HOST])dnl
+AC_CACHE_CHECK([for the toolset name used by Boost for $CXX], [boost_cv_lib_tag],
+[AC_LANG_PUSH([C++])dnl
+  boost_cv_lib_tag=unknown
+  # The following tests are mostly inspired by boost/config/auto_link.hpp
+  # The list is sorted to most recent/common to oldest compiler (in order
+  # to increase the likelihood of finding the right compiler with the
+  # least number of compilation attempt).
+  # Beware that some tests are sensible to the order (for instance, we must
+  # look for MinGW before looking for GCC3).
+  # I used one compilation test per compiler with a #error to recognize
+  # each compiler so that it works even when cross-compiling (let me know
+  # if you know a better approach).
+  # Known missing tags (known from Boost's tools/build/v2/tools/common.jam):
+  #   como, edg, kcc, bck, mp, sw, tru, xlc
+  # I'm not sure about my test for `il' (be careful: Intel's ICC pre-defines
+  # the same defines as GCC's).
+  # TODO: Move the test on GCC 4.4 up once it's released.
+  for i in \
+    _BOOST_gcc_test(4, 3) \
+    _BOOST_gcc_test(4, 2) \
+    _BOOST_gcc_test(4, 1) \
+    _BOOST_gcc_test(4, 0) \
+    "defined __GNUC__ && __GNUC__ == 3 && !defined __ICC \
+     && (defined WIN32 || defined WINNT || defined _WIN32 || defined __WIN32 \
+         || defined __WIN32__ || defined __WINNT || defined __WINNT__) @ mgw" \
+    _BOOST_gcc_test(3, 4) \
+    _BOOST_gcc_test(3, 3) \
+    "defined _MSC_VER && _MSC_VER >= 1500 @ vc90" \
+    "defined _MSC_VER && _MSC_VER == 1400 @ vc80" \
+    _BOOST_gcc_test(3, 2) \
+    "defined _MSC_VER && _MSC_VER == 1310 @ vc71" \
+    _BOOST_gcc_test(3, 1) \
+    _BOOST_gcc_test(3, 0) \
+    "defined __BORLANDC__ @ bcb" \
+    "defined __ICC && (defined __unix || defined __unix__) @ il" \
+    "defined __ICL @ iw" \
+    "defined _MSC_VER && _MSC_VER == 1300 @ vc7" \
+    _BOOST_gcc_test(4, 4) \
+    _BOOST_gcc_test(2, 95) \
+    "defined __MWERKS__ && __MWERKS__ <= 0x32FF @ cw9" \
+    "defined _MSC_VER && _MSC_VER < 1300 && !defined UNDER_CE @ vc6" \
+    "defined _MSC_VER && _MSC_VER < 1300 && defined UNDER_CE @ evc4" \
+    "defined __MWERKS__ && __MWERKS__ <= 0x31FF @ cw8"
+  do
+    boost_tag_test=`expr "X$i" : 'X\([[^@]]*\) @ '`
+    boost_tag=`expr "X$i" : 'X[[^@]]* @ \(.*\)'`
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#if $boost_tag_test
+/* OK */
+#else
+# error $boost_tag_test
+#endif
+]])], [boost_cv_lib_tag=$boost_tag; break], [])
+  done
+AC_LANG_POP([C++])dnl
+  case $boost_cv_lib_tag in #(
+    # Some newer (>= 1.35?) versions of Boost seem to only use "gcc" as opposed
+    # to "gcc41" for instance.
+    *-gcc | *'-gcc ') :;; #(  Don't re-add -gcc: it's already in there.
+    gcc*)
+      boost_tag_x=
+      case $host_os in #(
+        darwin*)
+          if test $boost_major_version -ge 136; then
+            # The `x' added in r46793 of Boost.
+            boost_tag_x=x
+          fi;;
+      esac
+      # We can specify multiple tags in this variable because it's used by
+      # BOOST_FIND_LIB that does a `for tag in -$boost_cv_lib_tag' ...
+      boost_cv_lib_tag="$boost_tag_x$boost_cv_lib_tag -${boost_tag_x}gcc"
+      ;; #(
+    unknown)
+      AC_MSG_WARN([[could not figure out which toolset name to use for $CXX]])
+      boost_cv_lib_tag=
+      ;;
+  esac
+])dnl end of AC_CACHE_CHECK
+])# _BOOST_FIND_COMPILER_TAG
+
+
+# _BOOST_GUESS_WHETHER_TO_USE_MT()
+# --------------------------------
+# Compile a small test to try to guess whether we should favor MT (Multi
+# Thread) flavors of Boost.  Sets boost_guess_use_mt accordingly.
+AC_DEFUN([_BOOST_GUESS_WHETHER_TO_USE_MT],
+[# Check whether we do better use `mt' even though we weren't ask to.
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#if defined _REENTRANT || defined _MT || defined __MT__
+/* use -mt */
+#else
+# error MT not needed
+#endif
+]])], [boost_guess_use_mt=:], [boost_guess_use_mt=false])
+])
+
+# _BOOST_AC_LINK_IFELSE(PROGRAM, [ACTION-IF-TRUE], [ACTION-IF-FALSE])
+# -------------------------------------------------------------------
+# Fork of _AC_LINK_IFELSE that preserves conftest.o across calls.  Fragile,
+# will break when Autoconf changes its internals.  Requires that you manually
+# rm -f conftest.$ac_objext in between to really different tests, otherwise
+# you will try to link a conftest.o left behind by a previous test.
+# Used to aggressively optimize BOOST_FIND_LIB (see the big comment in this
+# macro).
+#
+# Don't use "break" in the actions, as it would short-circuit some code
+# this macro runs after the actions.
+m4_define([_BOOST_AC_LINK_IFELSE],
+[m4_ifvaln([$1], [AC_LANG_CONFTEST([$1])])dnl
+rm -f conftest$ac_exeext
+boost_save_ac_ext=$ac_ext
+boost_use_source=:
+# If we already have a .o, re-use it.  We change $ac_ext so that $ac_link
+# tries to link the existing object file instead of compiling from source.
+test -f conftest.$ac_objext && ac_ext=$ac_objext && boost_use_source=false &&
+  _AS_ECHO_LOG([re-using the existing conftest.$ac_objext])
+AS_IF([_AC_DO_STDERR($ac_link) && {
+	 test -z "$ac_[]_AC_LANG_ABBREV[]_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext && {
+	 test "$cross_compiling" = yes ||
+	 $as_executable_p conftest$ac_exeext
+dnl FIXME: use AS_TEST_X instead when 2.61 is widespread enough.
+       }],
+      [$2],
+      [if $boost_use_source; then
+         _AC_MSG_LOG_CONFTEST
+       fi
+       $3])
+ac_objext=$boost_save_ac_objext
+ac_ext=$boost_save_ac_ext
+dnl Delete also the IPA/IPO (Inter Procedural Analysis/Optimization)
+dnl information created by the PGI compiler (conftest_ipa8_conftest.oo),
+dnl as it would interfere with the next link command.
+rm -f core conftest.err conftest_ipa8_conftest.oo \
+      conftest$ac_exeext m4_ifval([$1], [conftest.$ac_ext])[]dnl
+])# _BOOST_AC_LINK_IFELSE
+
+# Local Variables:
+# mode: autoconf
+# End: