Re: [v3] Erlang

[Leo Famulari <leo@famulari.name>]

On Mon, Apr 04, 2016 at 10:28:02AM +0200, Pjotr Prins wrote:
> On Sun, Apr 03, 2016 at 11:39:24PM -0400, Leo Famulari wrote:
> > Debian's package exhibits this problem. The timestamps are generated in
> > the following places in the source code. I don't know how to approach
> > this problem.
> > 
> > lib/kernel/test/global_SUITE_data/global_trace.erl:    io:format("The trace was generated at ~p~n", [EndTime]),
> > lib/reltool/bin/reltool.escript:    lists:flatten(io_lib:format("%% ~s generated at ~w ~w\n~p.\n\n",
> > lib/reltool/src/reltool_server.erl:    IoList = io_lib:format("%% config generated at ~w ~w\n~p.\n\n",
> > lib/reltool/src/reltool_target.erl:    RelIoList = io_lib:format("%% rel generated at ~w ~w\n~p.\n\n",
> > lib/reltool/src/reltool_target.erl:    ScriptIoList = io_lib:format("%% script generated at ~w ~w\n~p.\n\n",
> > lib/reltool/src/reltool_target.erl:            AppIoList = io_lib:format("%% app generated at ~w ~w\n~p.\n\n",
> > lib/reltool/src/reltool_target.erl:            AppIoList = io_lib:format("%% app generated at ~w ~w\n~p.\n\n",
> > lib/runtime_tools/src/erts_alloc_config.erl:	"generated at ~w-~2..0w-~2..0w ~2..0w:~2..0w.~2..0w by "
> > lib/sasl/src/systools_make.erl:	    io:format(Fd, "%% script generated at ~w ~w\n~p.\n",
> > lib/wx/src/gen/gl.erl:%% The program object's information log is updated and the program is generated at the time
> 
> If there is no easy work around I suggest simply patching them. Fortunately
> the Erlang compiler does not change much at this level.

The ideal solution would be to use the value of the environment variable
SOURCE_DATE_EPOCH if it is set, and else to behave as it does now.

> We can also contact Joe Armstrong, the author of Erlang, to discuss
> this point. He appears to be approachable. I am sure he is open to
> the idea of deterministic builds in a deterministic build system ;)

I could go to the Erlang IRC channel or forums (whatever they use) and
ask for advice. Since you are actually using Erlang, I think you would
be the better person to contact Joe Armstrong himself, if we decide to
do that.