write_compile_flags

#!/usr/bin/env escript

%%% Copyright 2010-2017 Manolis Papadakis <manopapad@gmail.com>,
%%%                     Eirini Arvaniti <eirinibob@gmail.com>
%%%                 and Kostis Sagonas <kostis@cs.ntua.gr>
%%%
%%% This file is part of PropEr.
%%%
%%% PropEr is free software: you can redistribute it and/or modify
%%% it under the terms of the GNU General Public License as published by
%%% the Free Software Foundation, either version 3 of the License, or
%%% (at your option) any later version.
%%%
%%% PropEr is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%%% GNU General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License
%%% along with PropEr.  If not, see <http://www.gnu.org/licenses/>.

%%% Author(s):   Manolis Papadakis and Kostis Sagonas
%%% Description: Compilation environment setup script: This script computes and
%%%              prints out the correct set of compilation flags for the
%%%              currently running version of the OTP.

-spec main([file:filename(),...]) -> 'ok'.
main([OutFile]) ->
    CurrVer = parse_version_string(erlang:system_info(version)),
    case CurrVer < [6,0] of
	false ->
	    {ok, Handle} = file:open(OutFile, [write]),
	    ToDefine =
		case CurrVer < [8,0] of
		    true  -> [];
		    false -> ["AT_LEAST_19"]
		end ++
		%% older than 18.0 => erl_scan:line() type not marked deprecated
		case CurrVer < [7,0] of
		    true  -> ["USE_ERL_SCAN_LINE"];
		    false -> []
		end,
	    Fun = fun(X) -> io:format(Handle, "-define(~s, 1).~n", [X]) end,
	    lists:foreach(Fun, ToDefine),
	    ok = file:close(Handle);
 	true  ->
	    halt(1) %% we do not support releases prior to 17
    end.

%% the stupid try-catch construct below is due to e.g. the R15A
%% release being denoted as having "5.9.pre" as version info :-(
-spec parse_version_string(string()) -> [non_neg_integer()].
parse_version_string(VerStr) ->
    [try list_to_integer(S)
     catch _:_ -> 0 end || S <- string:tokens(VerStr, ".")].