Problems with editable installs and setuptools >=64

[wch]

With Python 3.11.3, I installed Shiny in a venv for another project, with pip install -e ../py-shiny, but when I did this, the new project couldn't find the py.typed file.

I'm not 100% sure, but I believe that this is because setuptools >=64 uses a new mechanism instead of egg-link.
See:

• Editable installs are not recognized as having typing when using py.typed (setuptools v64 issue) python/mypy#13392 (comment)
• Due to limitation, static analysis don't support import hook used in editable install v64+ pypa/setuptools#3518

Apparently one can also install with strict mode (https://setuptools.pypa.io/en/latest/userguide/development_mode.html#strict-editable-installs):

pip install -e ../py-shiny --config-settings editable_mode=strict

I tried this with py-shiny, and it resulted in the JS and CSS web assets not being available when running an app. So we'll probably want to fix it in that case.

What does work for now is to use compat mode:

pip install -e ../py-shiny --config-settings editable_mode=compat