pip cannot uninstall an editable install in some cases

Description

When a project that contains only pyproject.toml is installed in editable mode, pip cannot uninstall it.

pip version

21.3.1

Python version

3.9

OS

Ubuntu

How to Reproduce

$ git clone [e-mail]:NeilGirdhar/tjax.git
Cloning into 'tjax'...
remote: Enumerating objects: 1819, done.
remote: Counting objects: 100% (223/223), done.
remote: Compressing objects: 100% (134/134), done.
remote: Total 1819 (delta 146), reused 134 (delta 89), pack-reused 1596
Receiving objects: 100% (1819/1819), 526.17 KiB | 3.96 MiB/s, done.
Resolving deltas: 100% (1288/1288), done.

$ pip install -e tjax
Obtaining file:///home/neil/tjax
  Installing build dependencies ... done
  Checking if build backend supports build_editable ... done
  Getting requirements to build wheel ... done
  Preparing metadata (pyproject.toml) ... done
Requirement already satisfied: networkx<3.0,>=2.4 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from tjax==0.14.2) (2.6.3)
Requirement already satisfied: yapf>=0.31 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from tjax==0.14.2) (0.31.0)
Requirement already satisfied: jax<0.3.0,>=0.2.21 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from tjax==0.14.2) (0.2.22)
Requirement already satisfied: optax<1,>=0 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from tjax==0.14.2) (0.0.9)
Requirement already satisfied: numpy>=1.21 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from tjax==0.14.2) (1.21.2)
Requirement already satisfied: matplotlib<4.0,>=3.3 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from tjax==0.14.2) (3.4.3)
Requirement already satisfied: colorful<0.6.0,>=0.5.4 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from tjax==0.14.2) (0.5.4)
Requirement already satisfied: absl-py in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from jax<0.3.0,>=0.2.21->tjax==0.14.2) (0.13.0)
Requirement already satisfied: opt_einsum in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from jax<0.3.0,>=0.2.21->tjax==0.14.2) (3.3.0)
Requirement already satisfied: scipy>=1.2.1 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from jax<0.3.0,>=0.2.21->tjax==0.14.2) (1.7.1)
Requirement already satisfied: pyparsing>=2.2.1 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from matplotlib<4.0,>=3.3->tjax==0.14.2) (2.4.7)
Requirement already satisfied: pillow>=6.2.0 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from matplotlib<4.0,>=3.3->tjax==0.14.2) (8.3.2)
Requirement already satisfied: python-dateutil>=2.7 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from matplotlib<4.0,>=3.3->tjax==0.14.2) (2.8.2)
Requirement already satisfied: kiwisolver>=1.0.1 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from matplotlib<4.0,>=3.3->tjax==0.14.2) (1.3.2)
Requirement already satisfied: cycler>=0.10 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from matplotlib<4.0,>=3.3->tjax==0.14.2) (0.10.0)
Requirement already satisfied: jaxlib>=0.1.37 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from optax<1,>=0->tjax==0.14.2) (0.1.71)
Requirement already satisfied: chex>=0.0.4 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from optax<1,>=0->tjax==0.14.2) (0.0.8)
Requirement already satisfied: six in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from absl-py->jax<0.3.0,>=0.2.21->tjax==0.14.2) (1.16.0)
Requirement already satisfied: dm-tree>=0.1.5 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from chex>=0.0.4->optax<1,>=0->tjax==0.14.2) (0.1.6)
Requirement already satisfied: toolz>=0.9.0 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from chex>=0.0.4->optax<1,>=0->tjax==0.14.2) (0.11.1)
Requirement already satisfied: flatbuffers<3.0,>=1.12 in ./.pyenv/versions/3.9.6/lib/python3.9/site-packages (from jaxlib>=0.1.37->optax<1,>=0->tjax==0.14.2) (2.0)
Installing collected packages: tjax
  Running setup.py develop for tjax
Successfully installed tjax

$ pip uninstall tjax
WARNING: Skipping tjax as it is not installed.

$ cat /home/neil/.pyenv/versions/3.9.6/lib/python3.9/site-packages/easy-install.pth
/home/neil/tjax

This uninstalls it:

$ cat /dev/null > /home/neil/.pyenv/versions/3.9.6/lib/python3.9/site-packages/easy-install.pth

Also, for some reason, the egg in ~/tjax is called “UNKNOWN.egg-info”, but pyproject.toml clearly specifies the name “tjax”.

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[sbidoul]

@NeilGirdhar both would be compatibility-breaking changes for pip, unfortunately.

[uranusjr]

if it’s going to install a project as editable using setuptools, it should use the name that Setuptools resolves for the package

Setuptools handle all the installation when being used to install an editable, and the project name is resolved by only setuptools, pip does not do anything here.

I agree with your earlier point there’s something pip can do to make things more sensible though. It’s true that a project can be setup.cfg-only, but a setup.cfg-only project without an explicit backend declaration in pyproject.toml is arguably more likely to be a user error than intentionally configured.