Version 4.8.0rc1 fails on Python 3.7 with SyntaxError in typing_extensions.py line 874

[andy-maier]

    from typing import SupportsIndex  # type: ignore
ImportError: cannot import name 'SupportsIndex' from 'typing' (/opt/hostedtoolcache/Python/3.7.17/x64/lib/python3.7/typing.py)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/runner/work/nocaselist/nocaselist/nocaselist/__init__.py", line 8, in <module>
    from ._nocaselist import *  # noqa: F403,F401
  File "/home/runner/work/nocaselist/nocaselist/nocaselist/_nocaselist.py", line 11, in <module>
    from typing_extensions import SupportsIndex  # Python <=3.7
  File "/home/runner/work/nocaselist/nocaselist/tmp_installtest/virtualenvs/nocaselist_test_test2/lib/python3.7/site-packages/typing_extensions-4.8.0rc1-py3.7.egg/typing_extensions.py", line 874
    def TypedDict(typename, fields=_marker, /, *, total=True, **kwargs):
                                            ^
SyntaxError: invalid syntax

Test run, for details: https://github.com/pywbem/nocaselist/actions/runs/6134182604/job/16646764117#step:19:72

Also, why does version 4.8.0rc1 even get installed? This happens during our install test, where we use different mechanisms for installing our package, and the issue happens in setup.py based install from the repo root directory. Is this another thing that broke in setup.py?

[AlexWaygood]

4.8.0rc1 no longer supports Python 3.7 (as Python 3.7 is now end-of-life), and this is stated in our pyproject.toml file:

typing_extensions/pyproject.toml

Line 12 in df9e322

requires-python = ">=3.8"

[andy-maier]

Thanks for the quick response.
That explains why the error appears.

And the setup.py based install that happily installs 4.8.0rc1 on Python 3.7 is not really your problem, I guess. It is just another indicator that we should get off of setup.py based installs.

As far as I'm concerned, this issue can be closed.

[AlexWaygood]

Looks like you're doing some complicated stuff here: https://github.com/pywbem/nocaselist/blob/master/tests/installtest/test_install.sh

All I can say is that pip install typing_extensions on Python 3.7 should cause pip's resolver to pick an older version of typing_extensions, as pip looks at the requires-python field before selecting which version to install. That means one of the following must be going on:

1. There's a bug in pip's resolver
2. you're doing something... Strange in your script that's confusing pip's resolver somehow and meaning that it's selecting a version of typing_extensions that's incompatible with Python 3.7 :-)

I haven't looked too deeply here, but I suspect it's (2) ;-)

[andy-maier]

The pip based install process correctly does pick up an older version.
It is only the setup.py based install that ends up installing 4.8.0rc1 on Python 3.7, and the install folks have long recommended to no longer use setup.py for install. I'll remove the setup.py based install from our install tests.