[quote=163133:@Paul Lefebvre]I don’t think that is the common interpretation of GPL binary usage.
My understanding is that you can supply a GPL binary (to run from the command line) as long as you make it easy to also get the source for the GPL binary.[/quote]
I looked at gnu.org the people that made the GPL and they have a section on this
http://www.gnu.org/licenses/gpl-faq.html#GPLInProprietarySystem
[quote]I’d like to incorporate GPL-covered software in my proprietary system. Can I do this? (#GPLInProprietarySystem)
You cannot incorporate GPL-covered software in a proprietary system. The goal of the GPL is to grant everyone the freedom to copy, redistribute, understand, and modify a program. If you could incorporate GPL-covered software into a non-free system, it would have the effect of making the GPL-covered software non-free too.
A system incorporating a GPL-covered program is an extended version of that program. The GPL says that any extended version of the program must be released under the GPL if it is released at all. This is for two reasons: to make sure that users who get the software get the freedom they should have, and to encourage people to give back improvements that they make.
[b]However, in many cases you can distribute the GPL-covered software alongside your proprietary system. To do this validly, you must make sure that the free and non-free programs communicate at arms length, that they are not combined in a way that would make them effectively a single program.
The difference between this and incorporating the GPL-covered software is partly a matter of substance and partly form. The substantive part is this: if the two programs are combined so that they become effectively two parts of one program, then you can't treat them as two separate programs. So the GPL has to cover the whole thing.[/b]
If the two programs remain well separated, like the compiler and the kernel, or like an editor and a shell, then you can treat them as two separate programsbut you have to do it properly. The issue is simply one of form: how you describe what you are doing. Why do we care about this? Because we want to make sure the users clearly understand the free status of the GPL-covered software in the collection.
If people were to distribute GPL-covered software calling it part of a system that users know is partly proprietary, users might be uncertain of their rights regarding the GPL-covered software. But if they know that what they have received is a free program plus another program, side by side, their rights will be clear.[/quote]
the also have this
https://www.gnu.org/licenses/gpl-faq.html#MereAggregation
[quote]Where’s the line between two separate programs, and one program with two parts? This is a legal question, which ultimately judges will decide. We believe that a proper criterion depends both on the mechanism of communication (exec, pipes, rpc, function calls within a shared address space, etc.) and the semantics of the communication (what kinds of information are interchanged).
If the modules are included in the same executable file, they are definitely combined in one program. If modules are designed to run linked together in a shared address space, that almost surely means combining them into one program.
By contrast, pipes, sockets and command-line arguments are communication mechanisms normally used between two separate programs. So when they are used for communication, the modules normally are separate programs. But if the semantics of the communication are intimate enough, exchanging complex internal data structures, that too could be a basis to consider the two parts as combined into a larger program.[/quote]
So my understanding is that if your program’s functionality depends on the GPL program, you can’t treat them as two seperate programs and therefore the GPL covers the whole thing.
I might be wrong. I’m not a lawyer either.
BTW on that page you’ll also see that there is a GCC Runtime Library Exception, so I think Xcode probably fell under that.