rebar.config.script

%% -*- mode: erlang; indent-tabs-mode: nil -*-

Conf0 = CONFIG,
HasOpt = {d,'HAS_MAPS',true},
FullOpt = {d,'HAS_FULL_KEYS',true},
RecOpt = {d,'NEW_REC_CORE',true},
RandOpt = {d,'NEW_RAND',true},

Version = case erlang:system_info(otp_release) of
              [$R,N1,N2|_] when is_integer(N1), is_integer(N2) ->
                  [N1,N2];
              Rel -> Rel
          end,

Copts0 = [{d,'ERLANG_VERSION',Version}],
Copts1 = if Version >= "17" -> Copts0 ++ [HasOpt];
            true -> Copts0
         end,
Copts2 = if Version >= "18" -> Copts1 ++ [FullOpt];
            true -> Copts1
         end,
Copts3 = if Version >= "19" -> Copts2 ++ [RecOpt,RandOpt];
            true -> Copts2
         end,
Copts = Copts3,                                 %This is it

case lists:keyfind(erl_opts, 1, Conf0) of
    {erl_opts,Opts} ->                          %Existing erl_opts
        NewOpts = {erl_opts,Opts ++ Copts},
        lists:keyreplace(erl_opts, 1, Conf0, NewOpts);
    false ->                                    %No erl_opts
        Conf0 ++ [{erl_opts,Copts}]
end.