ERROR: Error while checking for conflicts.

[zeroming2021]

• pip version: 21.0.1
• Python version:3.6
• Operating system: ubuntu-18.04 aarch64

pip install gevent==1.3.0
Collecting gevent==1.3.0
  Downloading gevent-1.3.0.tar.gz (4.6 MB)
     |████████████████████████████████| 4.6 MB 28 kB/s
Collecting greenlet>=0.4.13
  Downloading greenlet-1.0.0-cp36-cp36m-manylinux2014_aarch64.whl (156 kB)
     |████████████████████████████████| 156 kB 27 kB/s
Building wheels for collected packages: gevent
  Building wheel for gevent (setup.py) ... done
  Created wheel for gevent: filename=gevent-1.3.0-cp36-cp36m-linux_aarch64.whl size=2264513 sha256=a385ba45d6b9512bca9187c51358f7003c016d93d0473b7396bedf419fef2356
  Stored in directory: /root/.cache/pip/wheels/7f/bf/28/9a2b10c1cb1c8ce68a030b420ef16ee4e206d1652b0bffe5b5
Successfully built gevent
ERROR: Error while checking for conflicts. Please file an issue on pip's issue tracker: https://github.com/pypa/pip/issues/new
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/pip/_internal/commands/install.py", line 514, in _determine_conflicts
    return check_install_conflicts(to_install)
  File "/usr/local/lib/python3.6/dist-packages/pip/_internal/operations/check.py", line 115, in check_install_conflicts
    package_set, should_ignore=lambda name: name not in whitelist
  File "/usr/local/lib/python3.6/dist-packages/pip/_internal/operations/check.py", line 81, in check_package_set
    missed = req.marker.evaluate()
  File "/usr/local/lib/python3.6/dist-packages/pip/_vendor/packaging/markers.py", line 336, in evaluate
    return _evaluate_markers(self._markers, current_environment)
  File "/usr/local/lib/python3.6/dist-packages/pip/_vendor/packaging/markers.py", line 252, in _evaluate_markers
    lhs_value = _get_env(environment, lhs.value)
  File "/usr/local/lib/python3.6/dist-packages/pip/_vendor/packaging/markers.py", line 233, in _get_env
    "{0!r} does not exist in evaluation environment.".format(name)
pip._vendor.packaging.markers.UndefinedEnvironmentName: 'extra' does not exist in evaluation environment.
Installing collected packages: greenlet, gevent
Successfully installed gevent-1.3.0 greenlet-1.0.0

[uranusjr]

The req.marker.evaluate() line should be req.marker.evaluate({"extra": ""}) so extra markers can correctly resolve (to always false). I wonder why nobody reported this earlier; the issue should have crashed for a lot of packages with extras.

[ThijmenL98]

I'll create a PR for this.

[duthades]

Hi @uranusjr, I was trying to reproduce this error but for me the installation was successful without any errors.

pip install gevent==1.3.0
Defaulting to user installation because normal site-packages is not writeable
Looking in indexes: https://pypi.python.org/simple
Collecting gevent==1.3.0
  Using cached gevent-1.3.0.tar.gz (4.6 MB)
Collecting greenlet>=0.4.13
  Using cached greenlet-1.0.0-cp37-cp37m-manylinux2010_x86_64.whl (160 kB)
Building wheels for collected packages: gevent
  Building wheel for gevent (setup.py) ... done
  Created wheel for gevent: filename=gevent-1.3.0-cp37-cp37m-linux_x86_64.whl size=4683095 sha256=669489d0766a74b22bb9c7c8754ed150ec4240e48a214b22bd1645c8fa298dfd
  Stored in directory: /user/.cache/pip/wheels/1b/ae/d8/9b6f8a55ba3a537aeb0120bcac1efdce6125872ce4ce32cfb0
Successfully built gevent
Installing collected packages: greenlet, gevent
Successfully installed gevent-1.3.0 greenlet-1.0.0

[uranusjr]

That’s weird. Are you also on 21.0.1? (21.1 was released just recently so I’m playing this very safe and want to make sure you’re on the same version.)

[duthades]

I am using pip 21.1.

[uranusjr]

Could you try reproducing with 20.0.1? If this fails for you on 20.0.1, packaging probably has fixed this on their side and it should be safe to close this.

[duthades]

I tried with 20.0.1 and it is successful without errors. Yeah probably it's fixed from their side.

[uranusjr]

Let’s close this for now. We can always come back if someone hits this again for some reason.