Is it compatible with the GPL to construct (and distribute in binary and source form) a GPL licensed program with a "programming language" that only I have the compiler for and which I do not license to anyone?
E.g. something called C$ that compiles to MSIL with my own proprietary tool, but which does not compile with a C# compiler. The App would however use other modules (by other authors) that I use in the App and redistribute under the terms of the GPL as well.
Of course anyone using the App would be given the C$ source code as the GPL requires - just not the compiler. This way nobody could effectively compile or use the GPLd parts of the source code written by me in C$, and I could use GPLd modules as I please without effectively making the source code of my Application usable for anyone.
Would that be compilant?