numba/cuda/tests/doc_examples/ffi/functions.cu may not be packaged correctly

[gmarkall]

I've received a report of this failure from running the test suite on Windows with the conda package from the dev channel:

======================================================================
ERROR: test_ex_linking_cu (numba.cuda.tests.doc_examples.test_ffi.TestFFI)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\tests\doc_examples\test_ffi.py", line 42, in test_ex_linking_cu
    multiply_vectors[1, 32](r, x, y)
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\dispatcher.py", line 492, in __call__
    self.stream, self.sharedmem)
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\dispatcher.py", line 625, in call
    kernel = _dispatcher.Dispatcher._cuda_call(self, *args)
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\dispatcher.py", line 633, in _compile_for_args
    return self.compile(tuple(argtypes))
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\dispatcher.py", line 796, in compile
    kernel.bind()
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\dispatcher.py", line 178, in bind
    self._codelibrary.get_cufunc()
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\codegen.py", line 200, in get_cufunc
    cubin = self.get_cubin(cc=device.compute_capability)
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\codegen.py", line 175, in get_cubin
    linker.add_file_guess_ext(path)
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\cudadrv\driver.py", line 2630, in add_file_guess_ext
    self.add_cu_file(path)
  File "C:\ProgramData\Miniconda37\lib\site-packages\numba\cuda\cudadrv\driver.py", line 2620, in add_cu_file
    with open(path, 'rb') as f:
FileNotFoundError: [Errno 2] No such file or directory: 'C:\\ProgramData\\Miniconda37\\lib\\site-packages\\numba\\cuda\\tests\\doc_examples\\ffi\\functions.cu'

Possibly the packaging setup is not correct - I need to investigate this issue further, but have created the GH issue now to keep track publicly.

[gmarkall]

I was able to reproduce this on Linux too, with:

mamba create -n numba-issue-8253 python=3.7 numba/label/dev::numba nvidia::cuda-python=11.7.0
conda activate numba-issue-8253
NUMBA_CUDA_USE_NVIDIA_BINDING=1 python -m numba.runtests numba.cuda.tests.doc_examples

resulting in:

..E.......
======================================================================
ERROR: test_ex_linking_cu (numba.cuda.tests.doc_examples.test_ffi.TestFFI)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/tests/doc_examples/test_ffi.py", line 42, in test_ex_linking_cu
    multiply_vectors[1, 32](r, x, y)
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/dispatcher.py", line 492, in __call__
    self.stream, self.sharedmem)
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/dispatcher.py", line 625, in call
    kernel = _dispatcher.Dispatcher._cuda_call(self, *args)
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/dispatcher.py", line 633, in _compile_for_args
    return self.compile(tuple(argtypes))
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/dispatcher.py", line 796, in compile
    kernel.bind()
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/dispatcher.py", line 178, in bind
    self._codelibrary.get_cufunc()
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/codegen.py", line 200, in get_cufunc
    cubin = self.get_cubin(cc=device.compute_capability)
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/codegen.py", line 175, in get_cubin
    linker.add_file_guess_ext(path)
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/cudadrv/driver.py", line 2630, in add_file_guess_ext
    self.add_cu_file(path)
  File "/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/cudadrv/driver.py", line 2620, in add_cu_file
    with open(path, 'rb') as f:
FileNotFoundError: [Errno 2] No such file or directory: '/home/gmarkall/mambaforge/envs/numba-issue-8253/lib/python3.7/site-packages/numba/cuda/tests/doc_examples/ffi/functions.cu'

----------------------------------------------------------------------
Ran 10 tests in 4.525s

The file (and the ffi subfolder it lives in) is indeed absent:

$ ls $CONDA_PREFIX/lib/python3.7/site-packages/numba/cuda/tests/doc_examples
__init__.py        __pycache__         test_cg.py          test_cpu_gpu_compat.py  test_ffi.py
test_laplace.py    test_matmul.py      test_montecarlo.py  test_random.py
test_reduction.py  test_sessionize.py  test_vecadd.py