Problem:
Detection of the pynvim module is currently done by finding the first
Python interpreter in the `PATH` and checking if it can import pynvim.
This has several problems:
- Activation of an unrelated Python virtual environment will break
automatic detection, unless pynvim is also installed in that
environment.
- Installing pynvim to the expected location is difficult. User
installation into the system-wide or user-wide Python site area is now
deprecated. On Ubuntu 24.04 with Python 3.12, for example, the
command `pip install --user pynvim` now fails with the error message
`error: externally-managed-environment`.
- Users may create a dedicated virtual environment in which to install
pynvim, but Nvim won't detect it; instead, they must either activate
it before launching Nvim (which interferes with the user of other
virtual environments) or else hard-code the variable
`g:python3_host_prog` in their `init.vim` to the path of the correct
Python interpreter. Neither option is desirable.
Solution:
Expose pynvim's Python interpreter on the `PATH` under the
name `pynvim-python`. Typical user-flow:
1. User installs either uv or pipx.
2. User installs pynvim via:
```
uv tool install --upgrade pynvim
# Or:
pipx install --upgrade pynvim
```
With corresponding changes in pynvim https://github.com/neovim/pynvim/issues/593
the above user-flow is all that's needed for Nvim to detect the
installed location of pynvim, even if an unrelated Python virtual
environments is activated. It uses standard Python tooling to automate
the necessary creation of a Python virtual environment for pyenv and the
publication of `pynvim-python` to a directory on `PATH`.
(cherry picked from commit 5f8d4a248a)
Problem: #33022 didn't update `min_version` to 3.9, therefore Python 3.7
and 3.8 are still available.
Solution: Update `min_version` to 3.9.
(cherry picked from commit ade58885c4)
