Add pip to install_requires

[dvzrv]

setup.py:
Change setup() call to include pip in the list of dependencies passed to install_requires.
Pip is required for the mypy --install-types feature. Without specifically adding it, minimal environments (e.g. venvs) will not have pip installed and therefore have no way of installing required types (e.g. for tests).

Fixes #13580

[sobolevn]

I rarely see envs without pip but with mypy installed.
I don't really know how one can even do that: by running python mypy/setup.py install locally?

[dvzrv]

I rarely see envs without pip but with mypy installed.

That might be, but relying on transitive dependencies of some other package to pull in pip is less than ideal (basically broken).

I don't really know how one can even do that: by running python mypy/setup.py install locally?

This can happen if one does not specifically add it to the project's requirements. Tools such as PDM and also poetry will not install pip to your venv, if it is technically not required. If mypy does not pull in pip specifically and no other dependency does, a build container in CI only installing e.g. pdm and then bootstrapping the project requirements will not have pip.

[sobolevn]

Tools such as PDM and also poetry will not install pip to your venv

poetry part is 100% not correct. It installs pip:

~/Desktop                                                                            
» mkdir test && cd test

~/Desktop/test                                                                       
» poetry --version && poetry init
Poetry (version 1.2.1)

This command will guide you through creating your pyproject.toml config.

Package name [test]:  
Version [0.1.0]:  
Description []:  
Author [sobolevn <mail@sobolevn.me>, n to skip]:  
License []:  
Compatible Python versions [^3.10]:  

Would you like to define your main dependencies interactively? (yes/no) [yes] no
Would you like to define your development dependencies interactively? (yes/no) [yes] no
Generated file

[tool.poetry]
name = "test"
version = "0.1.0"
description = ""
authors = ["sobolevn <mail@sobolevn.me>"]
readme = "README.md"

[tool.poetry.dependencies]
python = "^3.10"


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


Do you confirm generation? (yes/no) [yes] 

~/Desktop/test                                                                       
» poetry install
Creating virtualenv test in /Users/sobolev/Desktop/test/.venv
Updating dependencies
Resolving dependencies... (0.1s)

Writing lock file

~/Desktop/test                                                                       
» poetry run which pip
/Users/sobolev/Desktop/test/.venv/bin/pip

[dvzrv]

Tools such as PDM and also poetry will not install pip to your venv

poetry part is 100% not correct. It installs pip:

Yeah, my bad (didn't check up on poetry again before writing my reply). I guess this only extents to PDM then (it does not install pip into the venv, but would instead rely on the system-wide installed pip if it is available) and poetry somehow installs some magic packages into the venv. 🤔
Given that pip is not a runtime requirement of any of the installed packages, that is basically just some implementation detail of poetry doing something in its own undocumented way.

Either way, a dependency on pip is a requirement if it is needed. Not all environments install their python packages using pip (e.g. all downstream distributions use system package management for that). So currently I don't have pip installed and have a fully functioning Python environment.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[yermulnik]

I'm not quite sure and hence am seeking for assistance: recently I found that MyPy cannot install pip dependencies in GitHub action: https://github.com/github/super-linter/issues/3450
Initially I was under impression that this was a super-linter issue since I use mypy via this linter automation, though then I found this change and now I'm wondering whether this should/might be fixed via https://github.com/python/mypy or maybe the issue lays deeper, e.g. in Actions runner (actions/runner#652)?
Thanks for any clue.

[dvzrv]

@yermulnik I don't believe this is related. pip has been added as an optional dependency only, installable by keyword (i.e. mypy[install-types]). Your problem in https://github.com/github/super-linter/issues/3450 looks like a directory permission issue.