Pip will install Python3-only packages on Python2

• Pip version: 9.0.1
• Python version: 2.7.3
• Operating system: Debian GNU/Linux 8 on Docker (running Docker image python:2.7)

Description:

I’ve published a package on PyPI which only supports Python3, and I’m sure I’ve set the setup.py metadata to describe it as only Python3… but I’ve discovered that someone running Python2.7 can do pip install <my package> and Pip will happily install it.

Is this expected behaviour? Have I made a mistake in my project’s setup.py?

Reading some of the discussion on #3984…

The over-specified version requirement thing is important. It’s way more irritating to have trouble installing a package that would work except it has incorrect metadata than to get a successful install of something that does not quite execute correctly.

… I’m not sure if this is a deliberate consequence of how version compatibility is checked?

What I’ve run:

$ docker run -it python:2.7 bash
root@aec4834958e1:/# pip --version
pip 9.0.1 from /usr/local/lib/python2.7/site-packages (python 2.7)
root@aec4834958e1:/# python --version
Python 2.7.13
root@aec4834958e1:/# cat /etc/issue
Debian GNU/Linux 8 \n \l

root@aec4834958e1:/# cd
root@aec4834958e1:~# pip install fang
Collecting fang
  Downloading fang-0.7.6.tar.gz
Building wheels for collected packages: fang
  Running setup.py bdist_wheel for fang ... done
  Stored in directory: /root/.cache/pip/wheels/b1/db/be/9d9370b32b6004b4ef5bba6a21d3e7da3e1443b97be6c1fd9e
Successfully built fang
Installing collected packages: fang
Successfully installed fang-0.7.6
root@aec4834958e1:~# python
Python 2.7.13 (default, Feb 28 2017, 22:13:47)
[GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import fang
>>> fang
<module 'fang' from '/usr/local/lib/python2.7/site-packages/fang/__init__.pyc'>

[ncraike]

I may have been using Pip ≥ 9, but I likely still didn’t get the desired behaviour because my package (Fang) doesn’t yet use the python_requires option in its setup.py.

On Wed, 9 Aug 2017 12:37 pm Lucy He [e-mail] wrote:

Which versions of pip starts to support python_requires? This post https://stackoverflow.com/questions/42238484/prevent-package-from-being-installed-on-old-python-versions/42792413#42792413 suggests it’s 9.0.0, but it looks like @ncraike https://github.com/ncraike was already using 9.0.1.

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[lucy-h]

Which versions of pip starts to support python_requires? This post suggests it’s 9.0.0, but it looks like @ncraike was already using 9.0.1.