poetry lock failing with OverrideNeeded and AssertionError on 1.2.0b2

[spoorn]

• [ x ] I am on the latest Poetry version.
• [ x ] I have searched the issues of this repo and believe that this is not a duplicate.
• [ x ] If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: AmazonLinux 2/Ubuntu
• Poetry version: 1.2.0b2
• Link of a Gist with the contents of your pyproject.toml file:

Issue

A simple poetry lock fails when I updated to 1.2.0b2. Downgrading to 1.2.0b1 succeeds the command as usual.

Error:

% poetry lock -v
Using virtualenv: /local/home/user/.virtualenvs/test
Updating dependencies
Resolving dependencies... (1.9s)

  OverrideNeeded

  ({Package('pandas', '1.4.2'): {'numpy': <Dependency numpy (>=1.18.5)>}}, {Package('pandas', '1.4.2'): {'numpy': <Dependency numpy (>=1.19.2)>}}, {Package('pandas', '1.4.2'): {'numpy': <Dependency numpy (>=1.20.0)>}})

  at ~/.local/share/pypoetry/venv/lib/python3.9/site-packages/poetry/puzzle/provider.py:757 in complete_package
      753│                     current_overrides.update({package: package_overrides})
      754│                     overrides.append(current_overrides)
      755│
      756│             if overrides:
    → 757│                 raise OverrideNeeded(*overrides)
      758│
      759│         # Modifying dependencies as needed
      760│         clean_dependencies = []
      761│         for dep in dependencies:

The following error occurred when trying to handle this error:


  AssertionError



  at ~/.local/share/pypoetry/venv/lib/python3.9/site-packages/poetry/mixology/partial_solution.py:151 in _register
      147│         name = assignment.dependency.complete_name
      148│         old_positive = self._positive.get(name)
      149│         if old_positive is not None:
      150│             value = old_positive.intersect(assignment)
    → 151│             assert value is not None
      152│             self._positive[name] = value
      153│
      154│             return
      155│

[spoorn]

Found out this happens if gluoncv = "0.10.5" is in pyproject.toml. Even if that's the only dependency I have in the entire file

[dimbleby]

https://github.com/python-poetry/poetry-core/blob/2bfcbe49dd887e1527e4e5e22cbd14caf4d9126a/src/poetry/core/semver/version.py#L92-L94 has the result that the constraint "=0.10.5" allows the version "0.10.5.post0".

But because this is unsymmetrical: when we intersect the constraints "==0.10.5" and "==0.10.5.post0" we get <empty>.

#379 is potentially relevant, inasmuch as it looks as though it introduces a similar asymmetry for local labels. (But if I'm right that introduces more instances of this problem, rather than fixing any.)

[dimbleby]

maybe allows is supposed to be unsymmetrical, but symmetry on intersection should be restored somehow?

[dimbleby]

diff --git a/src/poetry/core/semver/version.py b/src/poetry/core/semver/version.py
index 417d23a..356ac9e 100644
--- a/src/poetry/core/semver/version.py
+++ b/src/poetry/core/semver/version.py
@@ -107,6 +107,9 @@ class Version(PEP440Version, VersionRangeConstraint):
         if other.allows(self):
             return self

+        if isinstance(other, Version) and self.allows(other):
+            return other
+
         return EmptyConstraint()

     def union(self, other: VersionConstraint) -> VersionConstraint:

perhaps.

[radoering]

But because this is unsymmetrical: when we intersect the constraints "==0.10.5" and "==0.10.5.post0" we get <empty>.

Interestingly enough, according to PEP 440, I'd say it is correct that the intersection is empty. However, "==0.10.5" should not allow the version "0.10.5.post0" so the post release should never be selected in this example. I created python-poetry/poetry-core#396 to address this.

[github-actions]

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