[nickez]

That doesn't run at compile time though.

[MaxBarraclough]

I'm not sure what you mean here. It should use CMake's usual change-detection/dependency-tracking mechanism. [0]

The generation of the .h file from the .h.in file does happen at compile-time. (Well, at build time, right before the compiler is invoked.)

[0] https://stackoverflow.com/a/24246566/