Pyright should narrow except* to ExceptionGroup with non-base exceptions

[jakkdl]

It was changed from ExceptionGroup to BaseExceptionGroup in microsoft/pylance-release#4183
Related typeshed issue python/typeshed#12972

I'm not 100% if the typeshed issue will resolve except* handling in pyright, in case it would then we can directly resolve/close this. But in case it's hard-coded to always be BaseExceptionGroup and won't be changed by typeshed messing with __new__ then you might want to fix it right away.

repro:

from typing import reveal_type
try:
    raise ExceptionGroup("", [ValueError()])
except* ValueError as e:
    reveal_type(e)

$ python repro.py
Runtime type is 'ExceptionGroup'
$ pyright repro.py
  repro.py:5:17 - information: Type of "e" is "BaseExceptionGroup[ValueError]"
0 errors, 0 warnings, 1 information 

[erictraut]

I'm not sure what you mean. Could you provide a minimal code sample that demonstrates the behavior that you're seeing and your expected behavior?

[jakkdl]

ah sorry, added to OP

[erictraut]

I've created an enhancement request to track this: #9466.