Improve error message on PEP 440 constraint parsing failure

[roganartu]

• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the documentation and believe that my question is not covered.

Feature Request

Poetry version: 1.2.0a2

Problem

When any dependency in the dependency tree contains an invalid PEP 440 constraint, Poetry fails with the following error:

❯ poetry lock  
Updating dependencies
Resolving dependencies... (14.1s)

  InvalidVersion

  Invalid PEP 440 version: '3.5.'

  at /usr/scratch/xar/2ce5d136/lib/python3.8/site-packages/poetry/core/version/pep440/parser.py:67 in parse
       63│     @classmethod
       64│     def parse(cls, value: str, version_class: Optional[Type["PEP440Version"]] = None):
       65│         match = cls._regex.search(value) if value else None
       66│         if not match:
    →  67│             raise InvalidVersion(f"Invalid PEP 440 version: '{value}'")
       68│ 
       69│         if version_class is None:
       70│             from poetry.core.version.pep440.version import PEP440Version
       71│ 

The following error occurred when trying to handle this error:


  ValueError

  Could not parse version constraint: >=3.5.*

  at /usr/scratch/xar/2ce5d136/lib/python3.8/site-packages/poetry/core/semver/helpers.py:139 in parse_single_constraint
      135│ 
      136│         try:
      137│             version = Version.parse(version)
      138│         except ValueError:
    → 139│             raise ValueError(
      140│                 "Could not parse version constraint: {}".format(constraint)
      141│             )
      142│ 
      143│         if op == "<":

There is no mention of which package Poetry is attempting to parse the constraint for. This makes it extremely difficult to find out where the problem lies. In a project with even ten dependencies there could be hundreds of derived dependencies, and it could be any one of those which is failing.

I have attempted to increase the verbosity, but it is still rather difficult to work with. One needs to look at the dependencies that appear last in the output and then look for them in the output of poetry show --tree and then go looking up the setup.py for each of those until you find one with a constraint that matches the error.

Proposal

I propose that Poetry add the package name and version being parsed to this error message. eg:

  Could not parse version constraint: >=3.5.* from foo==1.2.3 (derived from bar=1.2.3)

Workaround

You can use pdb to find the package and version causing you problems, though it's non-obvious and has some issues so it's not really a workable solution for most users.

1. startup pdb with poetry (you may need to specify absolute paths to poetry here)

✗❯ python -m pdb poetry lock
> /usr/scratch/xar/2ce5d136/bin/poetry(3)<module>()
-> import re

2. set a breakpoint. We're running poetry==1.2.0a2 and the constraint exception raises from here:

(Pdb) b poetry/core/semver/helpers.py:139

3. let poetry run. It will be slower because pdb slows runtime down

(Pdb) c

4. This is where it gets tricky. The progress output continues printing, so you need to type pdb commands through it as they will get overwritten by shell escape sequences. When you see the following, you are actually getting a pdb prompt and can enter commands:

(Pdb) c
Updating dependencies
Resolving dependencies... (46.1s)> /path/to/python/lib/python3.8/site-packages/poetry/core/semver/helpers.py(139)parse_single_constraint()
-> raise ValueError(
Resolving dependencies... (109.8s) 

5. send the pdb commands up and args a few times to walk back up the stack, until you see something like this:

Resolving dependencies... (137.8s)
constraint = '>=3.5.*'
Resolving dependencies... (143.0s)
> /path/to/python/lib/python3.8/site-packages/poetry/core/semver/helpers.py(35)parse_constraint()
-> constraint_objects.append(parse_single_constraint(and_constraints[0]))
Resolving dependencies... (145.4s)
constraints = '>=3.5.*'
Resolving dependencies... (147.2s)
> /path/to/python/lib/python3.8/site-packages/poetry/core/packages/package.py(253)python_versions()
-> self._python_constraint = parse_constraint(value)
Resolving dependencies... (148.3s)
self = Package('pylint', '2.6.2')
value = '>=3.5.*'

Voila! This is the package that triggered the constraint exception. Bump it or pin it to a version that has a valid constraint (and if it's the latest release for that package, help out the maintainer with an issue or PR to fix it up!).
7. Send the q pdb command twice to exit the interpreter.

[idantene]

I'm also hitting this head-on and have to resort to source .venv/bin/activate first. Installed with a basic pip install poetry on the user-level, and anything following that (e.g. poetry install in a repo with poetry.lock) fails.

[neersighted]

You haven't provided sufficient detail to understand your particular scenario, but it sounds like you may be trying to install Poetry and your project both outside a virtual environment. That is full of foot-guns and ill-advised. Use of a virtual environment is strongly suggested and protects you against all manner of surprises.

[idantene]

I'm not sure I follow. Running poetry install creates the virtual environment and installs the dependencies in it.

Poetry itself is installed in the user space via pip.

[neersighted]

You mentioned manually managing a virtual environment -- without individual steps and command, what workflow you are using/what problem you are running into is unclear.

[robtaylor]

I'm still seeing the old error message as of head today:
poetry --version
Poetry (version 1.3.0.dev0)
poetry self show

Invalid PEP 440 version: '0.23ubuntu1'

[neersighted]

You're not on a HEAD version of poetry-core.

[robtaylor]

ahah, thank you!

[robtaylor]

Ok, defintely on head python-core now, Still same behaviour.
Looks like the try needs to move further up, as the exception is thrown on line 219: if not isinstance(version, Version):

> /home/robtaylor/.local/lib/python3.9/site-packages/poetry/core/packages/package.py(81)__init__()
->
  /home/robtaylor/.local/lib/python3.9/site-packages/poetry/core/packages/package.py(219)_set_version()
-> if not isinstance(version, Version):
  /home/robtaylor/.local/lib/python3.9/site-packages/poetry/core/version/pep440/version.py(182)parse()
-> return parse_pep440(value, cls)
  /home/robtaylor/.local/lib/python3.9/site-packages/poetry/core/version/pep440/parser.py(83)parse_pep440()
-> return PEP440Parser.parse(value, version_class)
  /home/robtaylor/.local/lib/python3.9/site-packages/poetry/core/version/pep440/parser.py(69)parse()
-> raise InvalidVersion(f"Invalid PEP 440 version: '{value}'")

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.