title: Can't install apex on Windows
body: <p>I want to install <a href="https://github.com/nvidia/apex" rel="nofollow noreferrer">apex</a> on my computer with Windows 10 and cuda 9.0. I know apex is not recommended to be installed on Windows, but I still very much want to try it. I used These two commands provided on <a href="https://github.com/nvidia/apex" rel="nofollow noreferrer">apex official website</a>:</p>
  
  <pre><code>pip install -v --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext"
  </code></pre>
  
  <p>and </p>
  
  <pre><code>pip install -v --no-cache-dir
  </code></pre>
  
  <p>but under both conditions got the error:</p>
  
  <pre><code>ERROR: You must give at least one requirement to install (see "pip help install")
  </code></pre>
  
  <p>The whole message is:</p>
  
  <pre><code>&gt;pip install -v --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext"
  C:\Users\Huiqi Xue\AppData\Local\conda\conda\envs\deeplearning\lib\site-packages\pip\_internal\commands\install.py:211: UserWarning: Disabling all use of wheels due to the use of --build-options / --global-options / --install-options.
    cmdoptions.check_install_build_global(options)
  Config variable 'Py_DEBUG' is unset, Python ABI tag may be incorrect
  Config variable 'WITH_PYMALLOC' is unset, Python ABI tag may be incorrect
  Created temporary directory: C:\Users\HUIQIX~1\AppData\Local\Temp\pip-ephem-wheel-cache-9dmaw_wt
  Created temporary directory: C:\Users\HUIQIX~1\AppData\Local\Temp\pip-req-tracker-rf4_u0bh
  Created requirements tracker 'C:\\Users\\HUIQIX~1\\AppData\\Local\\Temp\\pip-req-tracker-rf4_u0bh'
  Created temporary directory: C:\Users\HUIQIX~1\AppData\Local\Temp\pip-install-bflvtp4e
  Cleaning up...
  Removed build tracker 'C:\\Users\\HUIQIX~1\\AppData\\Local\\Temp\\pip-req-tracker-rf4_u0bh'
  ERROR: You must give at least one requirement to install (see "pip help install")
  Exception information:
  Traceback (most recent call last):
    File "C:\Users\Huiqi Xue\AppData\Local\conda\conda\envs\deeplearning\lib\site-packages\pip\_internal\cli\base_command.py", line 143, in main
      status = self.run(options, args)
    File "C:\Users\Huiqi Xue\AppData\Local\conda\conda\envs\deeplearning\lib\site-packages\pip\_internal\commands\install.py", line 293, in run
      self.name, wheel_cache
    File "C:\Users\Huiqi Xue\AppData\Local\conda\conda\envs\deeplearning\lib\site-packages\pip\_internal\cli\base_command.py", line 252, in populate_requirement_set
      '(see "pip help %(name)s")' % opts)
  pip._internal.exceptions.CommandError: You must give at least one requirement to install (see "pip help install")
  Config variable 'Py_DEBUG' is unset, Python ABI tag may be incorrect
  Config variable 'WITH_PYMALLOC' is unset, Python ABI tag may be incorrect
  1 location(s) to search for versions of pip:
  </code></pre>