Python 3.9.x & 3.10.x

[GBrachetta]

brew gist-logs <formula> link OR brew config AND brew doctor output

`brew install pipenv`
`brew install python@3.9`

Verification

• I ran brew update and am still able to reproduce my issue.
• I have resolved all warnings from brew doctor and that did not fix my problem.

What were you trying to do (and why)?

Installing Pipenv installed Python 3.10 as a dependency, yet it was not discoverable (python3 --version showed the default 3.8.3 installed with MacOS Monterey).

I installed 3.9 with brew install python@3.9 and this makes 3.9 the default python3 version, but I don't see a way to make 3.10 the default one, not even after reinstalling it with brew reinstall python@3.10.

What happened (include all command output)?

brew reinstall python@3.10 (<== reinstall because it was installed as a dependency by Pipenv)

$ which -a python3 
/opt/homebrew/bin/python3
/usr/bin/python3

(Python3.9 that's it, and is the one in path being used)

$ python3 --version
Python 3.9.9

(I found no way to use the brew installation of python 3.10)

What did you expect to happen?

I expected to have python 3.10.x as the default version after that was it the last version installed with Homebrew.

Step-by-step reproduction instructions (by running brew commands)

`brew install pipenv`
`brew install python@3.9`


$ python3 --version
Python 3.9.9

brew reinstall python@3.10

$ python3 --version
Python 3.9.9

(expected to see 3.10.x as the current version)

=====

If I run brew uninstall python@3.9:

$ python3 --version
Python 3.8.3

(default Monterey version, although I installed 3.10 with Homebrew).

Where is 3.10?

[bayandin]

I expected to have python 3.10.x as the default version after that was it the last version installed with Homebrew.

We have python@3.9 as a default python until #87075

brew info python@3.10 says:

...
python@3.10 is keg-only, which means it was not symlinked into /usr/local,
because this is an alternate version of another formula.

If you need to have python@3.10 first in your PATH, run:
  echo 'export PATH="/usr/local/opt/python@3.10/bin:$PATH"' >> /Users/$USER/.bash_profile

For compilers to find python@3.10 you may need to set:
  export LDFLAGS="-L/usr/local/opt/python@3.10/lib"

For pkg-config to find python@3.10 you may need to set:
  export PKG_CONFIG_PATH="/usr/local/opt/python@3.10/lib/pkgconfig"