AttributeError: type object '_CleanResult' has no attribute 'from_link' crash on v21.2.3

[murrple-1]

Description

AttributeError raised during pip install -r requirements.txt

Expected behavior

Installation should not raise error

pip version

21.2.3

Python version

3.6.14

OS

Docker image python:3.6.0 sha256:a1782fa44ef7b53a653d51e20b961b90847ee6b6b95eeba619db8aa8b868e440

How to Reproduce

1. Install pip 21.2.3 globally: pip install -U pip==21.2.3
2. Run pip install -r requirements.txt. requirements.txt looks like:

Django==3.0.2
psycopg2-binary==2.8.4
mysqlclient==1.4.6
ujson==2.0.2
uWSGI==2.0.18
jsonschema==3.2.0
pyotp==2.3.0
qrcode[pil]==6.1
filelock==3.0.12
pyparsing==2.4.6
validate-email==1.3
python-dateutil==2.8.1
password-hashing-python==0.3.0
quick-email==0.5.0

3. AttributeError is raised

I wish I could provide more than that.

Output

ERROR: Exception:
Traceback (most recent call last):
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/cli/base_command.py", line 173, in _main
    status = self.run(options, args)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/cli/req_command.py", line 203, in wrapper
    return func(self, options, args)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/commands/install.py", line 316, in run
    reqs, check_supported_wheels=not options.target_dir
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 95, in resolve
    collected.requirements, max_rounds=try_to_avoid_resolution_too_deep
  File "/builds/.venv/lib/python3.6/site-packages/pip/_vendor/resolvelib/resolvers.py", line 472, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_vendor/resolvelib/resolvers.py", line 366, in resolve
    failure_causes = self._attempt_to_pin_criterion(name)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_vendor/resolvelib/resolvers.py", line 212, in _attempt_to_pin_criterion
    criteria = self._get_updated_criteria(candidate)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_vendor/resolvelib/resolvers.py", line 203, in _get_updated_criteria
    self._add_to_criteria(criteria, requirement, parent=candidate)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_vendor/resolvelib/resolvers.py", line 168, in _add_to_criteria
    candidates=build_iter_view(matches),
  File "/builds/.venv/lib/python3.6/site-packages/pip/_vendor/resolvelib/structs.py", line 164, in build_iter_view
    matches = list(matches)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 417, in <genexpr>
    and all(req.is_satisfied_by(c) for req in requirements[identifier])
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 417, in <genexpr>
    and all(req.is_satisfied_by(c) for req in requirements[identifier])
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/resolution/resolvelib/requirements.py", line 39, in is_satisfied_by
    return candidate == self.candidate
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 172, in __eq__
    return links_equivalent(self._link, other._link)
  File "/builds/.venv/lib/python3.6/site-packages/pip/_internal/models/link.py", line 288, in links_equivalent
    return _CleanResult.from_link(link1) == _CleanResult.from_link(link2)
AttributeError: type object '_CleanResult' has no attribute 'from_link'

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[uranusjr]

Thanks for the report. This looks like yet another Python patch-level typing incompatibility.

https://docs.python.org/3.6/library/typing.html#typing.NamedTuple

Changed in version 3.6.1: Added support for default values, methods, and docstrings.

So everything other than 3.6.0 is fine, which is why we didn’t get this earlier. I hope Python never does this again, this 3.6.x compatibility level thing is painful.

[r-apabbathi]

@uranusjr Is this issue resolved? I still see this error

[DiddiLeija]

Well, @uranusjr moved the issue to the 21.2.4 milestone, so I think the change hasn't been released yet (the latest release is 21.2.3). Maybe a future release will include these changes.

[uranusjr]

Correct, this has not been released. I plan to do 21.2.4 this weekend. The report was unfortunately a few hours too late, otherwise I would’ve fixed this first before releasing 21.2.3.