I don’t know GPL3 well. I want to ship my software with GCC compiler so that users can write C++ and have it built on the target platform without any external IDE. Is it legal to have GCC deployed with game/engine automatically?
If it’s a situation where you can create binaries that use Unity engine, circumventing the need for licensing yet still using Unity, I don’t think it’s legal at all.
I also don’t think you will ever get permission from Unity staff about this from the forum. You should contact Unity legal.
It’s legal to use LUA or make a game maker that doesn’t avoid Unity or you don’t do any compilation. For example, a moddable game. A lot of people do this already.
But I understand you’re talking about using Unity Engine + your own compiler. That’s really out there and I don’t think anyone wants to touch that, so you should go higher up than the forum.
(I’m not a lawyer).
Are you trying to separately include the gcc compiler in the same distributable package as your game? Or are you trying to build the gcc compiler into the same executable as your game?
I want to use C++ for run-time scripting using custom IDE. I imagine that I would ship some kind of “gcc.exe” with some dlls and then I would call it using command line internally. All compilers support command line execution.
You might want to look at LLVM/Clang. It has a more permissive license.
http://releases.llvm.org/2.8/LICENSE.TXT
http://llvm.org/docs/DeveloperPolicy.html#license
It is a drop-in replacement for gcc, and you can compile various input languages to various outputs once you’re familiar with LLVM. I believe LLVM is basis for Unity tools like il2cpp.
You might want to look at embedding AngelScriot into your project. That will give the users the ability to script stuff in C++. I haven’t used it myself but I have friends that do.