new union syntax doesn't work on Literals

[DetachHead]

from __future__ import annotations

from typing import Literal

Foo = Literal[1, 2]

Bar = Foo | Literal[3] # error: Unsupported left operand type for | ("object")

https://mypy-play.net/?mypy=latest&python=3.10&gist=3a429dfa3e9e3b692aac25887027ab69

[sobolevn]

This also happens without __future__ import, python3.9:

from typing import Literal

Foo = Literal[1, 2]
Bar = Foo | Literal[3]
# error: Invalid type alias: expression is not a valid type
# error: Unsupported left operand type for | ("object")

Will fix it right now, thanks!

[sobolevn]

On python3.10 it generates a single error:

» mypy out/ex.py --show-traceback
out/ex.py:4: error: Unsupported left operand type for | ("object")

[JelleZijlstra]

On 3.9 without the import the error is correct since | doesn't work at runtime in 3.9. But it should not error in 3.10 or with the future import on, or in stringified annotations.