That the individually-protected work is also included in an compilation which is itself licensed under MIT does not remove or loosen any licensing requirements on the smaller work.
Why is that in violation of the license? The only condition specified in the MIT/Expat license is this:
>The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
Each file is not "the Software". "The Software" means the Zig/Zen projects as a whole. The "above copyright notice and this permission notice" is included in the copy of Zen. Therefore, it is in compliance.
I wrote in another comment:
>In addition, the Zen headers say "This project may be licensed under the terms of the ConnectFree Reference Source License" and "See the LICENSE file at the root of this project for complete information". This statement is enough to imply that the project as a whole is covered by the specified LICENSE file.
Can you give any support for this which is not your own "I say so because that's how I understand what I have read"?
That is, can you give a link of some court case where your claim was confirmed, or a link to a project where some big company changed the copyright lines in some library source files, when these lines were previously MIT licensed?
If not, repeating your own claims in many posts here doesn't make your claims more believable.
I still understand that every source file (as in, having the lines that produce executable code) containing a copyright is a "software" where the copyright lines have to be preserved as soon as the author initially wrote the lines, and I need some independent evidence, as stated before, to be convinced otherwise.
For the sake of the argument, let's grant you the premise that each file is its own "software" (as the word is used in the MIT/Expat). The only requirement of the license is this: "The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software." So even if connectFree removed all the copyright notices in the source code files, they still meet that condition because the original Zig license is included in their modified copy of Zig. It doesn't matter what the definition of "software" is here, because they meet the conditions regardless of what that definition is.
Here is some of the license text:
> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software") [...]
That seems to me to indicate that it applies to the whole software package and not any single file (unless you could call that single file a "software" in its own right, maybe?)
Meanwhile, the text in each individual file only says this:
> Copyright (c) 2015 Andrew Kelley
> This file is part of zig, which is MIT licensed. See http://opensource.org/licenses/MIT
One way you could check is if each of the files has their own copyright and license notice, and the license notice includes, directly or by reference, terms which require preservation of the accompanying copyright notice.