Add source file in Apache 2.0 licensed project

Question

I want to add a source file (which is under GPL v2.0 (not in v2.0+)) in a project which is under Apache 2.0 license.

As mentioned on GNU's website

Please note that this license is not compatible with GPL version 2 ...

Where, this word is used for Apache 2.0 license.

I wonder, can I add a source file which is under different license and incompatible with project license? And what would? If I explicitly mention about that file and its license in a LICENSE file (usually this file is present in root directory of the project).

Answer 1

Saying that licences are incompatible means that the work to which those licences apply can not be used in a way that simultaneously satisfies all the conditions of the incompatible licences. If the project accepted your contribution, it would make the project unusable, since no user could then satisfy the conditions required to have the copyright licence necessary to enable its use. Mentioning what you've done in the LICENSE file doesn't make that problem go away.

What is likely to happen is that the project refuses to accept the contribution. They are completely at liberty to do so: no person is obliged to accept another's offer of help.

If you're involved enough with the project that you have commit rights to the project's code repository, and you check it in anyway, then once it's noticed it'll likely be removed, or rewritten by someone else who doesn't insist on using GPL. There may be some knockback on you; the project may formally request that you not do that again, or even remove your commit privileges.