### We might want to force the C++ standard.
AC_ARG_ENABLE(cxx-mode,
AS_HELP_STRING([--enable-cxx-mode],[choose C++ standard (default: 14, then 11)]),,
### We might want to force the C++ standard.
AC_ARG_ENABLE(cxx-mode,
AS_HELP_STRING([--enable-cxx-mode],[choose C++ standard (default: 14, then 11)]),,