INTERNAL ERROR: maximum semantic analysis iteration count reached on self-referential union

[kmurphy4]

Crash Report

Under some specific conditions, mypy crashes when creating type aliases for unions with self-referential variants.

Specifically, both of these work fine:

X: ty.TypeAlias = ty.Union[
    ty.Set["X"],
    ty.Sequence["X"],
]

Y: ty.TypeAlias = ty.Union[
    ty.Sequence[ty.Optional["Y"]],
]

but this crashes:

Z: ty.TypeAlias = ty.Union[
    ty.Set["Z"],
    ty.Sequence[ty.Optional["Z"]],
]

with

main.py: error: INTERNAL ERROR: maximum semantic analysis iteration count reached

To Reproduce

https://mypy-play.net/?mypy=1.9.0&python=3.12&flags=show-traceback&gist=5f48179cab35cd594aca11d797bf530d