Adding License Statement (MIT and Apache)

[TimmFitschen]

There is an open issue regarding this (resolve #12) and the latest statement of one of the contributers pointed towards a MIT license. However, I copied the license statement from another repository of rust-lang (https://github.com/rust-lang/rust-clippy) because I expect this to be compliant with the general licensing strategy of rust-lang.

I set the copyright to "Copyright 2017-2021 The Rust Project Developers" as these are the dates of the first and latest commit in this repository.

Please let me know if can improve anything. I don't want to pressure the rust-lang community into publishing this with the proposed licenses. I hope that the license issue can be closed soon, tho. Have a nice day, and thank you for reviewing this PR!

[sfackler]

This definitely seems plausible to me, but I think it'd be best to pull in someone to double check that this is the right move. Thoughts @Mark-Simulacrum?

[sfackler]

I asked about this on Zulip: https://rust-lang.zulipchat.com/#narrow/stream/231349-t-core.2Flicensing

[lopopolo]

Chiming in here, I have borrowed the rustup install snippet for a debian build container in several multi-stage Dockerfiles. I'd love to make sure I'm properly attributing my use of this code and abiding by its license:

• Upgrade rustup in build containers to 1.25.1 artichoke/docker-artichoke-nightly#113

[JoelMarcey]

@Mark-Simulacrum @pietroalbini @sfackler I can't immediately see an issue with dual licensing this project exactly the same as is done with other projects in rust-lang. I don't think we have a concept of "default" license that says, if there is not an explicit license in a project, then the default is X. I think some sort of explicit license for this project would be good, whatever we choose that to be.

[pietroalbini]

I agree we need to add licenses to this repository, leaning towards our standard MIT OR Apache-2.0 license. I am not a lawyer, but I don't think there is a concept of a "default" license though, and I think we need to ask consent from all contributors before we can relicense the repository (or replace the changes made by people who don't agree to the relicense).

[JoelMarcey]

@pietroalbini Agree. IANAL either, but as I understand it we would indeed have to get approval from all contributors to retroactively apply the license to the commits before the license was added. There are only 10 contributors it looks like, but getting that approval will require some planning.