During pdm install: pip._vendor.packaging.markers.UndefinedEnvironmentName: 'extra' does not exist in evaluation environment.

[GooseYArd]

I'm pretty sure this is not a pdm bug but suspect that another pdm user might have a workaround.

I've converted a module from poetry to pdm which transitively depends on the "requests-cache" module. requests-cache supports the pip extras feature but the module which introduces the dependency just uses "requests-cache" and not "requests-cache[]".

Running pdm lock generates this snippet:

[[package]]
name = "requests-cache"
version = "0.7.2"
requires_python = ">=3.6,<4.0"
summary = "A transparent, persistent cache for the requests library"
dependencies = [
    "attrs<22.0,>=21.2",
    "cattrs<2.0,>=1.7; (python_version >= \"3.7\" and python_version < \"4.0\") and (extra == \"all\" or extra == \"bson\" or extra == \"json\" or extra == \"yaml\" or extra == \"mongodb\")",
    "itsdangerous>=2.0.1",
    "pyyaml>=5.4",
    "requests<3.0,>=2.17",
    "url-normalize<2.0,>=1.4",
]

However, if I execute pdm install, I get a crash in one the pip libraries (traceback below). Searching for other instances of this issue, I did come across pypa/pip#3953, which seems to indicate that "extra" expressions aren't permitted in requirements.txt files, so maybe they're also not permitted in the constraint expressions that are ultimately passed to resolvelib?

Any suggestions for other things to check?

Thanks in advance!!!

Error occurs
Traceback (most recent call last):
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pdm/termui.py", line 192, in logging
    yield logger
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pdm/cli/actions.py", line 111, in resolve_candidates_from_lockfile
    mapping, *_ = resolve(
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pdm/resolver/core.py", line 30, in resolve
    result = resolver.resolve(requirements, max_rounds)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/resolvelib/resolvers.py", line 472, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/resolvelib/resolvers.py", line 366, in resolve
    failure_causes = self._attempt_to_pin_criterion(name)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/resolvelib/resolvers.py", line 212, in _attempt_to_pin_criterion
    criteria = self._get_updated_criteria(candidate)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/resolvelib/resolvers.py", line 202, in _get_updated_criteria
    for requirement in self._p.get_dependencies(candidate=candidate):
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pdm/resolver/providers.py", line 87, in get_dependencies
    deps, requires_python, summary = self.repository.get_dependencies(candidate)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pdm/models/repositories.py", line 400, in get_dependencies
    reqs = [
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pdm/models/repositories.py", line 404, in <listcomp>
    or req.marker.evaluate(self.environment.marker_environment)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pip/_vendor/packaging/markers.py", line 336, in evaluate
    return _evaluate_markers(self._markers, current_environment)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pip/_vendor/packaging/markers.py", line 247, in _evaluate_markers
    groups[-1].append(_evaluate_markers(marker, environment))
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pip/_vendor/packaging/markers.py", line 252, in _evaluate_markers
    lhs_value = _get_env(environment, lhs.value)
  File "/home/bailey/.pyenv/versions/3.9.6/lib/python3.9/site-packages/pip/_vendor/packaging/markers.py", line 232, in _get_env
    raise UndefinedEnvironmentName(
pip._vendor.packaging.markers.UndefinedEnvironmentName: 'extra' does not exist in evaluation environment.

[frostming]

Thanks. I've created issue #559 to track this.

[GooseYArd]

Thanks for the info @frostming! I apologize in advance-- although I've read through the marker code a little, I haven't had enough time to understand it much. Although I'm using the head of main now, I still get the crash at markers.py:232, but I noticed that one of the test cases you added seems to match the scenario that triggers my crash (i.e. "(os_name == 'nt') and (extra == 'foo' or extra == 'bar')").

In my case, extras is set to a list of values, and that later results in the crash. Since pip seems not to support evaluation of extras at resolution time, is there more that needs doing to support this case?

Thanks in advance, I'm enjoying using the tool a lot so far, and this is the only glitch I've encountered!

[frostming]

Oh, I forgot to tell you that the lock file is wrong, it shouldn't produce markers like that. Try relocking and the whole requirement will be gone.