Summary

Code for reproduction:

import typing

a: typing.Hashable = "GOOD"
a: typing.Sequence[typing.Hashable] = ["GOOD"]
a: typing.Hashable | typing.Sequence[typing.Hashable] = "GOOD"
a: typing.Hashable | typing.Sequence[typing.Hashable] = ["FAILS"]

With ty==0.0.1a19 it passes but with ty==0.0.1a20 the last line fails:

error[invalid-assignment]: Object of type `list[@Todo]` is not assignable to `Hashable`
 --> x.py:6:1
  |
4 | a: typing.Sequence[typing.Hashable] = ["GOOD"]
5 | a: typing.Hashable | typing.Sequence[typing.Hashable] = "GOOD"
6 | a: typing.Hashable | typing.Sequence[typing.Hashable] = ["FAILS"]
  | ^
  |
info: rule `invalid-assignment` is enabled by default

If I change Hashable to str or Sequence to list then it works. But typing.Hashable | typing.Sequence[typing.Hashable] is a common type in Pandas. E.g. https://github.com/pandas-dev/pandas/blob/3c14b71c8f965ff316b22dfb3d87839361f55297/pandas/core/frame.py#L6319 I'm not sure how to call those methods with ty==0.0.1a20 if I want to pass in a list of strings.

Version

0.0.1a20