Looks like the afcuda cmake is not searching/checking that the required cudnn.h file is available:

cmake
success
make afcuda
...
In file included from /local1/wtambellini/arrayfire/src/backend/cuda/convolve.cpp:15:0:
/local1/wtambellini/arrayfire/src/backend/cuda/cudnn.hpp:13:19: fatal error: cudnn.h: No such file or directory
#include <cudnn.h>

Expected behavior : cmake to at least fail if cudnn.h not findable in usual suspect dirs (/usr/local/cuda/include, ...)

Ref:
https://github.com/soumith/cudnn.torch/blob/master/cmake/FindCUDNN.cmake