Build fixes: query numpy path directly; setup pyproject.toml for pip

[roryyorke]

This is intended to fix #3, #63, and #65. It works on Ubuntu 18.04, I'll still try to test it on Windows 10. I don't have an iOS (MacOS? OSX? ... ) machine to test on.

The test is to prepare a source tarball with python setup.py sdist -- this needs numpy and scikit-build. Then, in a fresh environment without those packages, or anything other than pip, run pip install slycot.0.3.blah.tar.gz (substitute version number for blah). pip install . might be the same thing, I'm not sure.

[jakevdp]

I'm not sure what the issue is, but I get an error when running pip install . on this branch in a clean VM

$ pip install .
Processing /content/Slycot
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
ERROR: Command "/usr/bin/python3 /usr/local/lib/python3.6/dist-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmp2l0ltqp8" failed with error code 1 in /tmp/pip-req-build-yzrxe9ke

[jakevdp]

It succeeds if I remove pyproject.toml (as long as I've pre-installed all the build deps)

[jakevdp]

For completeness:

$ pip --version
pip 19.1.1 from /usr/local/lib/python3.6/dist-packages/pip (python 3.6)
$ python -c "import wheel; print(wheel.__version__)"
0.33.4

[jakevdp]

Ah, ran with --verbose and got more info about the error:

$ pip install git+https://github.com/roryyorke/Slycot@rory/more-build-fixes --verbose
<!-- snip --> 
Running command /usr/bin/python3 /usr/local/lib/python3.6/dist-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmpwymdjbra
  Traceback (most recent call last):
    File "/usr/local/lib/python3.6/dist-packages/pip/_vendor/pep517/_in_process.py", line 207, in <module>
      main()
    File "/usr/local/lib/python3.6/dist-packages/pip/_vendor/pep517/_in_process.py", line 197, in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
    File "/usr/local/lib/python3.6/dist-packages/pip/_vendor/pep517/_in_process.py", line 54, in get_requires_for_build_wheel
      return hook(config_settings)
    File "/usr/local/lib/python3.6/dist-packages/setuptools/build_meta.py", line 145, in get_requires_for_build_wheel
      return self._get_build_requires(config_settings, requirements=['wheel'])
    File "/usr/local/lib/python3.6/dist-packages/setuptools/build_meta.py", line 126, in _get_build_requires
      self.run_setup()
    File "/usr/local/lib/python3.6/dist-packages/setuptools/build_meta.py", line 234, in run_setup
      self).run_setup(setup_script=setup_script)
    File "/usr/local/lib/python3.6/dist-packages/setuptools/build_meta.py", line 141, in run_setup
      exec(compile(code, __file__, 'exec'), locals())
    File "setup.py", line 295, in <module>
      setup_package()
    File "setup.py", line 228, in setup_package
      VERSION, gitrevision = get_version_info(src_path)
    File "setup.py", line 153, in get_version_info
      FULLVERSION, GIT_REVISION, GIT_CYCLE = git_version(srcdir)
    File "setup.py", line 101, in git_version
      out = _minimal_ext_cmd(['git', 'rev-parse', 'HEAD'], srcdir)
    File "setup.py", line 94, in _minimal_ext_cmd
      % (proc.returncode, errmsg))
  __main__.GitError: git err; return code 128, error message:
    'fatal: not a git repository (or any of the parent directories): .git'
  Getting requirements to build wheel ... error
<!-- snip --> 

Looks like the root of the issue is in the setup.py method that generates git hash versions.

[roryyorke]

Thanks for that - I could reproduce with pip install git+file:///(etc). setup.py was trying to determine the source path (for git invocation) from sys.argv[0], which ended up being some script in Python's site-package; setup.py now uses __file__ to find itself.

[jakevdp]

Great! Confirmed I can now pip install slycot directly from this branch without issues.

[jakevdp]

It might be worth testing this in travis - I think it would be sufficient to replace python setup.py install with pip install ., and I don't think you'd lose any coverage with that change.

[roryyorke]

conda build -c conda-forge conda-recipe-openblas still works on Windows with this branch. I couldn't get a non-Conda build (i.e., pip install) to work, but I don't think it ever has.