I am very confused about how the MIT license works in detail. In layman's terms, I understand the following:
- If you distribute copies of MIT source, then you must include the license, and the rights in it are granted to the receiver.
- If you modify MIT source (which is permitted) then you can distribute the modifications, but the derived work is not automatically MIT.
The MIT license only speaks in terms of copies.
- Must modified copies include the MIT license? Note that the modified copy might not even contain any code in common with the original - for example, if it was translated into another language.
- Is there any distinction when the code has not been modified per se, but is merely included as part of a larger work (e.g. suppose you copied an MIT file and pasted it inside a closed-source project)? I believe that the combined work is, technically, a derived work of both parts. If the answer to the first question is "no", then what about this case? (if it's "yes", then there is surely no distinction in this case)
- If so, does the MIT license thus included actually convey any rights? I think it must do, or I can't understand how the license worked for the original work. But I also think it must not, because if it did then my translated MIT library would appear to automatically be MIT (which is wrong).
Assume that the modified work is intended to be distributed as something other than MIT - for concreteness, let's say it's fully proprietary.
: Incidentally, I don't see how this is implied exactly by the license text, but it seems everyone (including me) accepts it's allowed. The license refers only to "copies", so it looks like what it says is that you can modify copies and distribute copies, but not that you can distribute modified copies.