Poetry locks Python2.x constraints for Python3.x project

[fj-dt]

• [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: macOS Big Sur 11.2.3 (20D91)
• Poetry version: 1.1.5
• Link of a Gist with the contents of your pyproject.toml file: https://gist.github.com/fj-dt/369d0397470e4fe4c13ab389df7ab62e

Issue

I am using Python3 and I want to install beautifulsoup4==4.9.1. beautifulsoup4==4.9.1 has a dependency called soupsieve. soupsieve has a constraints specifically for Python 2.x version which says soupsieve<2.0.

When I lock beautifulsoup4==4.9.1, I see that Poetry does not find the correct constraints for Python 3.7. It should install soupsieve version 2.x but it installs soupsieve version 1.x.

I double-checked that my venv is using Python 3.x and that Poetry also uses Python 3.x. I also tried with pip, pip-tools and pipenv; they are all locking the right version.

Here's the lock file

[[package]]
name = "beautifulsoup4"
version = "4.9.1"
description = "Screen-scraping library"
category = "main"
optional = false
python-versions = "*"

[package.dependencies]
soupsieve = [
    ">1.2",
    "<2.0",
]

[package.extras]
html5lib = ["html5lib"]
lxml = ["lxml"]

[[package]]
name = "soupsieve"
version = "1.9.6"
description = "A modern CSS selector implementation for Beautiful Soup."
category = "main"
optional = false
python-versions = "*"

[metadata]
lock-version = "1.1"
python-versions = "^3.7"
content-hash = "9fbe508dc2cd47d10bd6f762cf0cb01df11125d7a76860b74d5dc695517dea4f"

[metadata.files]
beautifulsoup4 = [
    {file = "beautifulsoup4-4.9.1-py2-none-any.whl", hash = "sha256:e718f2342e2e099b640a34ab782407b7b676f47ee272d6739e60b8ea23829f2c"},
    {file = "beautifulsoup4-4.9.1-py3-none-any.whl", hash = "sha256:a6237df3c32ccfaee4fd201c8f5f9d9df619b93121d01353a64a73ce8c6ef9a8"},
    {file = "beautifulsoup4-4.9.1.tar.gz", hash = "sha256:73cc4d115b96f79c7d77c1c7f7a0a8d4c57860d1041df407dd1aae7f07a77fd7"},
]
soupsieve = [
    {file = "soupsieve-1.9.6-py2.py3-none-any.whl", hash = "sha256:feb1e937fa26a69e08436aad4a9037cd7e1d4c7212909502ba30701247ff8abd"},
    {file = "soupsieve-1.9.6.tar.gz", hash = "sha256:7985bacc98c34923a439967c1a602dc4f1e15f923b6fcf02344184f86cc7efaa"},
]

Thanks for your help!

[dimbleby]

At 4.9.1, beautifulsoup expressed their soupsieve requirement by executing conditional code in setup.py:

install_requires=["soupsieve>1.2"]
if sys.version_info.major == 2:
    install_requires.append("soupsieve<2.0")

this is hard for poetry to handle, it looks as though it has 'seen' both branches but is not able to realise that one of them is only meant for python 2.

in later releases they moved to markers:

install_requires=[
    "soupsieve >1.2; python_version>='3.0'",
    "soupsieve >1.2, <2.0; python_version<'3.0'",
],

which is much better, and I expect poetry would handle just fine

At this point beautifulsoup has dropped support for python2 altogether and none of this is relevant, I expect it's safe to close this out.

[Secrus]

Yes, this is no longer relevant. Also, a lot has changed since poetry 1.1.5. You can check it with the newest version and if that's still a problem, open a new issue.

[dimbleby]

For what it's worth I expect this would still be a problem with beautifulsoup 4.9.1: it still is hard for poetry to understand setup.py with conditional code.

Encouraging the ecosystem to move to markers - as beautifulsoup already did - is the best way to make this sort of thing more reliable.

[github-actions[bot]]

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.