As soon as I build my project, the code of that software is copied into my program. (I didn't modify the code at all, just copied it in my program) I did this so I don't need to load/download it dynamically. If this causes any problems with copyright, I can change it any time

@Daniel It is a bit complicated, but if you include GPL software in one binary with your own, then you are obliged to make your own GPL too. If both programs install separately and your software only uses GPL one (kinda like an user would), then you are OK and can licence any way you want.

@Daniel Can you add more details about this process to your question? It sounds like you are attempting some sort of end run around the GPL.

@Daniel Can we just step back a bit: "open source" refers to the permissions you give when you pass the code to someone else. It doesn't place any other obligation on you (e.g. you don't have to run a Github project or anything). Do you specifically want to stop your friends from passing on the software to their friends because you plan to sell it some day? Or do you just not care? What are you trying to achieve? Suppose you just put a GPL license on your code and passed copies to your friends, who then passed copies to their friends, and someone puts it on the Net. Is that bad?

@Daniel: the answer to your last question is in the last para of my answer.

I don't plan to sell it. I just want my software to spread as less as possible. This is because of a reason which is to difficult for me to explain in english (English is not my main language)

@Daniel making it open source doesn't mean it will spread more. It just means you give your friends a copy of the source code and you understand they have the right to share it again. But they're your friends: just ask them not to exercise that right, ask them not to share it with anyone even though they can legally choose to share it.

@terdon Well... Let's see how it turns out. Thanks

@Daniel, licensing your program to others under the GPL does not require you to distribute the source code with it. It does, however, require you at least to include a written offer to provide source code to licensees, which you are obligated to fulfill if one of your licensees asks. Most people do either include the source with the binary or provide for a means for people to download it at their own initiative, but those are not the only alternatives.

@JohnBollinger: What about distributing a package containing a GPL library, along with a compiled object file which contains no GPL source code, and a source-code project which can be used to build a program that combines the GPL library with an object file that contains no GPL code. Someone with that project would be free to make any changes to the GPL parts and rebuild it, changing the executable's behavior in any manner that could be achieved by such modification,

@supercat, that sounds like it might work, but the resulting whole program is derived from GPL code (or so the FSF would claim), and the package you describe is a distribution of that whole program, therefore it has to be licensed under the GPL. The sticky point then is whether the binary-only library is construed as part of the program or as a separate and independent entity. I am inclined to think that such a determination would need to be made on a case by case basis. If the binary lib is construed as part of the program then it needs to be GPL'd too.

@JohnBollinger: If a linked binary were included in the distribution, then that would be covered under the GPL, but there's no requirement that distribution medium that contains GPL software cannot also contain other legally-independent things which are not covered by the GPL; a linked object module that contains no GPL code would be legally independent in that regard.

@JohnBollinger: The intention may be that the recipient of the medium combine the parts to produce a binary that contains a mixture of GPL and non-GPL content, but GPL explicitly allows the formation of derivative works in the form of binaries that contain closed-source software so long as they are not distrubuted. The purpose of any build scripts that combine open and source code material wouldn't be to facilitate violations of the GPL, but rather facilitate compliance with it.

@supercat, I acknowledge that it is possible for GPL and and non-GPL components to be distributed on the same media, and to be used in combination without violating the GPL. For example, GPL-encumbered Windows programs may be distributed (in source or binary form) together with a copy of Microsoft's C runtime library, and I am not inclined to think that any violation of the GPL or Microsoft's redistribution license is inherent in performing such a distribution.

However, @supercat, I am not inclined to accept that partitioning a program as you describe is sufficient to relieve parts of it from GPL licensing requirements. It is certainly contrary to the spirit and intention of the GPL. My expectation is that the legal analysis would hinge on whether the binary-only part was a genuinely separate and independent entity. Relevant questions include whether it also distributed separately from the GPL part and whether it is useful to anything other than the GPL part.

In Germany, some GPL programmer sued a company and argued that the Linux kernel is a "Sammelwerk" and therefore in a certain situation the company had to observe the GPL. The GPL programmer won the process. However, that classification ("Sammelwerk") has a drastic impact: The Linux kernel is not seen as "one work" but every kernel module is seen as "work on its own". ... and German law seems explicitly to allow adding works of different licenses (for example: closed-source) to a "Sammelwerk" and does not allow some license (GPL) to forbid this!