Cryptic error for using ArborX when CUDA is not loaded

Created by: aprokop

Situation:

• Kokkos is compiled with CUDA backend (with nvcc_wrapper)
• Arborx is compiled against that Kokkos and installed

If one tries to compile an example against ArborX installation, use -DCMAKE_CXX_COMPILER="nvcc_wrapper" but forgets to load/have nvcc in the path, the error is very cryptic:

CMake Error at /usr/share/cmake-3.10/Modules/FindMPI.cmake:970 (try_compile):
  Cannot copy output executable

    ''

  to destination specified by COPY_FILE:

    '<snip>/build/CMakeFiles/FindMPI/test_mpi_CXX.bin'

  Unable to find the executable at any of:

    <snip>/build/CMakeFiles/CMakeTmp/cmTC_7c7de
    <snip>/build/CMakeFiles/CMakeTmp/Debug/cmTC_7c7de
    <snip>/build/CMakeFiles/CMakeTmp/Development/cmTC_7c7de\

It is completely opaque. Does anyone has any ideas whether we can produce any helpful messages or diagnostics to help users understand what's going on?