Clarify licensing

[carllerche]

The licensing of this repository states:

regex is primarily distributed under the terms of both the MIT license and
the Apache License (Version 2.0), with portions covered by various BSD-like
licenses.

• which portions are covered by "various BSD-like licenses"?
• What is a BSD-like license? Which license?
• How is software licensed under MIT AND Apache 2? This implies that it carries the super set of both licenses (not that the user gets to pick). What does the super set of both licenses mean?

[BurntSushi]

The same exact phrasing is used for rust proper. Probably "... with portions covered by various BSD-like licenses" doesn't make sense in this context. The intent was to match the licensing of the Rust project proper.

Perhaps rust is the wrong precise example to copy. Maybe Cargo's verbiage would be better? I note though that your last question still applies to Cargo's verbiage, which means it isn't specific to this crate.

[carllerche]

The rust repo contains this file: https://github.com/rust-lang/rust/blob/master/COPYRIGHT

The and verbiage is included as part of "Short version for non-lawyers:"

In the longer version:

Except as otherwise noted (below and/or in individual files), Rust is
licensed under the Apache License, Version 2.0 <LICENSE-APACHE> or
<http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
<LICENSE-MIT> or <http://opensource.org/licenses/MIT>, at your option.

It seems to me that the short version using the and terminology is not an official license statement.

[BurntSushi]

cc @alexcrichton @aturon

[BurntSushi]

@carllerche Could you please respond to my comments about Cargo?

[carllerche]

@BurntSushi Yes, this issue is not limited to this crate.

I believe that using and terminology does not mean the intent (dual licensing). I believe every crate that copied the "short version" of the copyright snippet from the Rust repository did so incorrectly as the correct verbiage is below.

Something like this would be (more) correct (I believe): https://github.com/seanmonstar/reqwest#license

Of course, I am not a lawyer and I also don't think any of this has been tested in court. I only am bringing it up because I believe the verbiage does not convey the licensing intent and this could cause problems for organizations that require clear licensing.

[BurntSushi]

I'm happy with whatever the Rust project decides. (In other words, I think this issue is filled in the wrong place, but I'm not sure what the right place is.)

[alexcrichton]

@BurntSushi I've done this in all my projects.