Emacs-Lua: question about the license of one file

[Eduardo Ochs]

Hi list,

I am working on a package that contains a module written in C++ that
loads a Lua interpreter, and that implements a REPL that lets us run
that interpreter interactively from Emacs. It is here:

  https://github.com/edrx/emacs-lua

At this moment my package is just a poorly-documented prototype, but I
would like to submit it to ELPA when it grows up.

QUESTION. The code in the module in C++ was written by a guy who sent
it to the Lua mailing list. His message is here:

  http://lua-users.org/lists/lua-l/2021-03/msg00084.html

Here is my version of his code:

  https://raw.githubusercontent.com/edrx/emacs-lua/main/emlua.cpp
  http://angg.twu.net/emacs-lua/emlua.cpp.html
  http://angg.twu.net/emacs-lua/emlua.cpp

When my REPL became functional I sent him an e-mail saying that I
would like to prepare the package to submit it to ELPA in the future,
and asked him what he thought about doing the paperwork thing... and I
told him that if he preferred a paperworkless way that _I guessed_
that he could just send an e-mail to the Lua mailing list declaring
his code to be in the public domain, but I would have to check that
possibility with people who are more knowledgeable than me - and he
said something equivalent to "wow, yes, great, please check!"...

So: can we do that? And are there any other licenses that you would
recommend besides public domain?

  Cheers and thanks in advance =),
    Eduardo Ochs
    http://angg.twu.net/