dnl LX_C_IFDEF(MACRO-NAME, ACTION-IF-DEF, ACTION-IF-NOT-DEF)

 dnl

 dnl Check for the definition of macro MACRO-NAME using the current

 dnl language's compiler.

 dnl

 dnl Orignally written by Ludovic Courtès <ludo@chbouib.org>

 AC_DEFUN([LX_C_IFDEF],

   [AC_COMPILE_IFELSE([#ifndef $1

                       # error "Macro $1 is undefined!"

                       /* For some compilers (eg. SGI's CC), #error is not

                          enough...  */

                       please, do fail

                       #endif],

                      [$2], [$3])])

 dnl LX_CXX_COMPILER_VENDOR(VENDOR-NAME, [NICKNAME])

 dnl

 dnl Set VENDOR-NAME to the lower-case name of the compiler vendor or

 dnl `unknown' if the compiler's vendor is unknown. `compaq' means the

 dnl CXX compiler as available on Tru64/OSF1/Digital Unix on Alpha

 dnl machines. If NICKNAME is provided, set it to the compiler's usual

 dnl name (eg. `g++', `cxx', `aCC', etc.).

 dnl

 dnl Based on work of Ludovic Courtès <ludo@chbouib.org>

 AC_DEFUN([LX_CXX_COMPILER_VENDOR],

   [AC_REQUIRE([AC_PROG_CXX])

    AC_REQUIRE([AC_PROG_CXXCPP])

    AC_CACHE_CHECK([the C++ compiler vendor],

     [lx_cv_cxx_compiler_vendor],

     [AC_LANG_PUSH([C++])

      dnl Intel's icpc

      LX_C_IFDEF([__INTEL_COMPILER],

        [lx_cv_cxx_compiler_vendor=intel],

        [dnl GNU C++

         LX_C_IFDEF([__GNUG__],

          [lx_cv_cxx_compiler_vendor=gnu],

          [LX_C_IFDEF([__DECCXX],

            [lx_cv_cxx_compiler_vendor=compaq],

            [dnl HP's aCC

             LX_C_IFDEF([__HP_aCC],

              [lx_cv_cxx_compiler_vendor=hp],

              [dnl SGI CC

               LX_C_IFDEF([__sgi],

                [lx_cv_cxx_compiler_vendor=sgi],

                [dnl Note:  We are using the C compiler because VC++ doesn't

                 dnl recognize `.cc'(which is used by `configure') as a C++ file

                 dnl extension and requires `/TP' to be passed.

                 AC_LANG_PUSH([C])

                 LX_C_IFDEF([_MSC_VER],

                   [lx_cv_cxx_compiler_vendor=microsoft],

                   [lx_cv_cxx_compiler_vendor=unknown])

                 AC_LANG_POP()])])])])])

      AC_LANG_POP()])

    $1="$lx_cv_cxx_compiler_vendor"

    dnl The compiler nickname

    ifelse([$2], , [],

      [case "$lx_cv_cxx_compiler_vendor" in

         intel)     $2=icpc;;

         gnu)       $2=g++;;

         compaq)    $2=cxx;;

         hp)        $2=aCC;;

         sgi)       $2=CC;;

         microsoft) $2=cl;;

         *)         $2=unknown;;

       esac])])

 dnl Set some debugging and error reporting related compiler flags.

 dnl uses lx_user_cxxflags

 AC_DEFUN([LX_SET_CXXFLAGS],

   [AC_ARG_ENABLE([debug],

 AS_HELP_STRING([--enable-debug@<:@=yes|no|full@:>@], [build with debugging support])

 AS_HELP_STRING([--disable-debug], [build without debugging support @<:@default@:>@]),

      [], [enable_debug=no])

    LX_CXX_COMPILER_VENDOR([lx_cxx_compiler_vendor])

    AC_MSG_CHECKING([whether to build with debugging support])

    if test x"$enable_debug" != x"no"; then

      AC_DEFINE([DEBUG], [1], [Define for debugging support])

      lx_gnu_cxxflags="-ansi -pedantic -Wall -Wextra"

      lx_intel_cxxflags="-g"

      lx_unknown_cxxflags="-g"

      if test x"$enable_debug" = x"yes"; then

        lx_gnu_cxxflags="-g $lx_gnu_cxxflags"

        AC_MSG_RESULT([yes])

      else

        lx_gnu_cxxflags="-g3 --no-inline $lx_gnu_cxxflags"

        AC_MSG_RESULT([full])

      fi

      if test x"$lx_cxx_compiler_vendor" = x"gnu"; then

        CXXFLAGS="$lx_user_cxxflags $lx_gnu_cxxflags"

      elif test x"$lx_cxx_compiler_vendor" = x"intel"; then

        CXXFLAGS="$lx_user_cxxflags $lx_intel_cxxflags"

      else

        CXXFLAGS="$lx_user_cxxflags $lx_unknown_cxxflags"

      fi

    else

      AC_MSG_RESULT([no])

    fi

    AC_ARG_ENABLE([extra-warnings],

 AS_HELP_STRING([--enable-extra-warnings], [enable extra warning messages])

 AS_HELP_STRING([--disable-extra-warnings], [disable extra warning messages @<:@default@:>@]),

      [],[enable_extra_warnings=no])

    AC_MSG_CHECKING(whether to enable extra warning flags)

    if test x"$enable_extra_warnings" != x"no"; then

      if test x"$lx_cxx_compiler_vendor" = x"gnu"; then

        CXXFLAGS="$CXXFLAGS -ansi -pedantic -Wall -Wextra"

        CXXFLAGS="$CXXFLAGS -Wfloat-equal -Wundef -Wendif-labels -Wshadow"

        CXXFLAGS="$CXXFLAGS -Wpointer-arith -Wcast-qual -Wcast-align"

        CXXFLAGS="$CXXFLAGS -Wwrite-strings -Wconversion -Waggregate-return"

        CXXFLAGS="$CXXFLAGS -Wmissing-noreturn -Wmissing-format-attribute"

        CXXFLAGS="$CXXFLAGS -Wpacked -Wpadded -Wredundant-decls"

        CXXFLAGS="$CXXFLAGS -Wunreachable-code -Winline -Winvalid-pch"

        CXXFLAGS="$CXXFLAGS -Wlong-long -Wdisabled-optimization"

        CXXFLAGS="$CXXFLAGS -Wstack-protector"

      elif test x"$lx_cxx_compiler_vendor" = x"intel"; then

        CXXFLAGS="$CXXFLAGS -w2"

      fi

      AC_MSG_RESULT([yes])

    else

      AC_MSG_RESULT([no])

    fi])