BOOSTLIBDIR=`echo$BOOST_LDFLAGS | sed -e's/[^\/]*//'`
if test"x$ax_boost_user_regex_lib"="x";then
for libextension in`ls$BOOSTLIBDIR/libboost_regex*.so*$BOOSTLIBDIR/libboost_regex*.dylib*$BOOSTLIBDIR/libboost_regex*.a* 2>/dev/null | sed 's,.*/,,' | sed -e's;^lib\(boost_regex.*\)\.so.*$;\1;'-e's;^lib\(boost_regex.*\)\.dylib.*;\1;'-e's;^lib\(boost_regex.*\)\.a.*$;\1;'`;do
for libextension in`ls$BOOSTLIBDIR/boost_regex*.dll*$BOOSTLIBDIR/boost_regex*.a* 2>/dev/null | sed 's,.*/,,' | sed -e's;^\(boost_regex.*\)\.dll.*$;\1;'-e's;^\(boost_regex.*\)\.a.*$;\1;'`;do
AC_CHECK_HEADER([filesystem], [], [AC_MSG_ERROR([The file <filesystem> is missing, perhaps you should install a more recent libstdc++ implementation.])])
dnl check if we need stdc++fs as library
AC_MSG_CHECKING([if linking to stdc++fs is required])