Yes, it is non-free. I’m not sure what the question is here: it’s well established that CC BY-NC-SA is non-free. The public domain portion is just the TweetNaCl piece it subsumes.

The purpose of talking about it is to warn off someone who might otherwise integrate it into their product. I don’t see this as complaining!

It's free for non-commercial purposes. But yes, it's true that if you want to use it in a commercial product you'll have to work out some other arrangement.

CC BY-NC-SA does not permit the use of the software for commercial purposes. Thus it is not free for commercial purposes. This violates a few generally accepted principles of software freedom:

* Freedom 0 of the Free Software Definition: The freedom to run the program as you wish, for any purpose (freedom 0).

* Point 6 of the Debian Free Software Guidelines (DFSG): No Discrimination Against Fields of Endeavor: The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.

* Point 6 of the Open Source Definition (OSD): No Discrimination Against Fields of Endeavor: The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.

FSD: https://www.gnu.org/philosophy/free-sw.en.html

DFSG: https://www.debian.org/social_contract#guidelines

OSD: https://opensource.org/docs/osd

Fair enough. I have added the GPLv3 as an option.

Hence, non-free. Perhaps we are having a language confusion; here, I mean free as in freedom, not as in beer.

Fair enough. I have added the GPLv3 as an option.

Software that is free only for non-commercial purposes is considered to be non-free software.

Fair enough. I have added the GPLv3 as an option.

France, and many other jurisdictions, don't recognise the concept of releasing directly into the public domain, so in this case would leave you high and dry in the future theoretical of the original author changing his mind about your use of his library.

If people really want to release into the public domain, public domain with French exceptions like CC0 are the best option.

TweetNaCl-js is under such a "public domain with fallback" license, so I'm not sure what you are complaining about.

(And even if it weren't, pure use is not as critical as e.g. wanting to contribute to it)

It is unlikely in the extreme that DJB would ever try to enforce the copyright on TweetNaCl. But yes, if you want to use SC4 in France, I guess that's a risk you'll have to take. There's nothing I can do about that.