poetry doesn't parse python constraints when markers are present

[maciejskorski]

• I am on the latest Poetry version.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

Clarifies in-depth the common root-cause for several reported issues
#3444
#4959
#4958

• OS version and name: Linux
• Poetry version: 1.2.0a2
• Python 3.8

Issue

poetry fails to parse python constraints when markers appear.

This should be supported as per the official documentation.

This also has a side effect on the performance and the lock file, as this way packages bypass early compatibility checks on versions; also wrong versions may get installed.

Reproduce
The following test confirms that poetry does not populate python constraints due to markers

[tool.poetry.dependencies]
python = "3.8"
pandas = [
    {version="1.3.2",python="3.9",markers="sys_platform=='linux'"},
    {version="1.3.1",python="3.8"}
]

then setting a breakpoint inside complete_package method gives

# [(d.name+str(d._constraint),d._python_constraint) for d in requires]
[('pandas1.3.2', <VersionRange (*)>), ('pandas1.3.1', <Version 3.8>)]

Furthermore, due to the broken constraint poetry would pick up the wrong (1.3.2) version to install.

[maciejskorski]

Root-Cause

The issue is inside the function poetry.core.factory.configure_package, which translates poetry.local_config (json-like) into package (python object) see

Indeed, consider

from poetry.core.pyproject.toml import PyProjectTOML
from poetry.core.factory import Factory
local_config=PyProjectTOML(path='pyproject.toml').poetry_config
# local_config['dependencies'] has all python constraints
package = Factory.get_package('test','0.0.0')
package = Factory.configure_package(package,local_config,'')
[d.marker for d in package._dependency_groups['default']._dependencies]
# python constraints not populated :-(

What needs to be fixed is the method Factory.create_dependency from poetry.core.factory

To reproduce the issue

constraint = {'version': '1.3.2', 'python': '3.9', 'markers': "sys_platform=='linux'"}
Factory.create_dependency('pandas', constraint)._python_constraint
# this gives wrongly version 
constraint.pop('markers')
Factory.create_dependency('pandas', constraint)._python_constraint
# correct version once markers deleted

What happens is the code logic excludes populating python constraints when markers are present.

But fixing this seems to require changes to poetry.core. Any thoughts?

[github-actions]

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