[CMake] FindCUDA ignores project dependencies when separable compilation is on

[Irwin Zaid]

Hi all,

Just wanted to mention this issue I've run into.

I have a project (libdynd -- https://github.com/libdynd/libdynd) that 
uses FindCUDA to deal with CUDA compilation. A part of our library is 
generated at compile-time, which we handle by the command 
"add_dependencies(libdynd some_exe)", where "some_exe" is an executable 
built with a custom command. This part of our library needs to be 
present before anything else is built.

So far, everything has worked great, with and without CUDA. However, I 
found that by just turning separable compilation on, via 
set(CUDA_SEPARABLE_COMPILATION ON), the dependency I've added is then 
ignored and the necessary files are not generated. Basically, CMake goes 
straight to NVCC without running the custom command.

This seems to me to be something wrong with FindCUDA, but it is of 
course possible that I've done something wrong. Any help would be 
appreciated!

Irwin