If you invoke AC_LANG(C++) above AC_PROG_LIBTOOL, you will find that $ac_ext is "c" after AC_PROG_LIBTOOL has been run, and invoking AC_LANG(C++) again will not dispatch the necessary shell code to fix this again since AC_LANG thinks everything is hunky dory. You need to switch to another language and back again to get it right... Lars J
