Failing to install apex

Start by reading setup.py around lines 17 and 130 and inspect how CUDA_HOME is obtained; reproduce the reported install command with the stated Python and PyTorch versions. Done means metadata generation no longer fails at the shown TypeError and the CUDA extension installation path is verified.

LightXML/apex$ pip install -v --disable-pip-version-check --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" ./
WARNING: Disabling all use of wheels due to the use of --build-option / --global-option / --install-option.
Using pip 22.0.2 from /home/celso/projects/venvs/LightXML/lib/python3.8/site-packages/pip (python 3.8)
Processing /home/celso/projects/LightXML/apex
  Running command python setup.py egg_info
  Traceback (most recent call last):
    File "<string>", line 2, in <module>
    File "<pip-setuptools-caller>", line 34, in <module>
    File "/home/celso/projects/LightXML/apex/setup.py", line 130, in <module>
      _, bare_metal_version = get_cuda_bare_metal_version(CUDA_HOME)
    File "/home/celso/projects/LightXML/apex/setup.py", line 17, in get_cuda_bare_metal_version
      raw_output = subprocess.check_output([cuda_dir + "/bin/nvcc", "-V"], universal_newlines=True)
  TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'


  torch.__version__  = 1.5.1


  error: subprocess-exited-with-error
  
  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> See above for output.
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
  full command: /home/celso/projects/venvs/LightXML/bin/python -c '
  exec(compile('"'"''"'"''"'"'
  # This is <pip-setuptools-caller> -- a caller that pip uses to run setup.py
  #
  # - It imports setuptools before invoking setup.py, to enable projects that directly
  #   import from `distutils.core` to work with newer packaging standards.
  # - It provides a clear error message when setuptools is not installed.
  # - It sets `sys.argv[0]` to the underlying `setup.py`, when invoking `setup.py` so
  #   setuptools doesn'"'"'t think the script is `-c`. This avoids the following warning:
  #     manifest_maker: standard file '"'"'-c'"'"' not found".
  # - It generates a shim setup.py, for handling setup.cfg-only projects.
  import os, sys, tokenize
  
  try:
      import setuptools
  except ImportError as error:
      print(
          "ERROR: Can not execute `setup.py` since setuptools is not available in "
          "the build environment.",
          file=sys.stderr,
      )
      sys.exit(1)
  
  __file__ = %r
  sys.argv[0] = __file__
  
  if os.path.exists(__file__):
      filename = __file__
      with tokenize.open(__file__) as f:
          setup_py_code = f.read()
  else:
      filename = "<auto-generated setuptools caller>"
      setup_py_code = "from setuptools import setup; setup()"
  
  exec(compile(setup_py_code, filename, "exec"))
  '"'"''"'"''"'"' % ('"'"'/home/celso/projects/LightXML/apex/setup.py'"'"',), "<pip-setuptools-caller>", "exec"))' egg_info --egg-base /tmp/pip-pip-egg-info-_j2pmc0w
  cwd: /home/celso/projects/LightXML/apex/
  Preparing metadata (setup.py) ... error
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.