Poetry removes numpy for some versions of python and pandas

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

• OS version and name:

System
Platform: darwin
OS:       posix
Python:   /usr/local/opt/python@3.10/Frameworks/Python.framework/Versions/3.10

• Poetry version: Poetry version 1.1.12

Issue

pyproject.toml:

[tool.poetry]
name = "test"
version = "0.1.0"
description = ""
authors = [""]

[tool.poetry.dependencies]
python = "^3.9"
pandas = "^1.3.0"

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

If I run poetry update with the pyproject.toml shown above, the correct dependencies are installed. If I change the Python version to python = "~3.9" and run poetry update again, poetry shows:

Updating dependencies
Resolving dependencies... (0.1s)

Writing lock file

Package operations: 0 installs, 0 updates, 1 removal

  • Removing numpy (1.22.1)

This seems wrong, since pandas won't run without numpy. What's going on here?

Reproduce the report with the supplied pyproject.toml, first using python = "^3.9" and then python = "~3.9", and run poetry update. Trace the dependency-resolution path responsible for removing numpy even though pandas is installed; done means the resolver handles this constraint consistently and the scenario has regression coverage.