Simplify intersections with typevars whose upper bound is covered by a union of negative elements #1456
Description
There appear to be lots of other cases where you can have a TypeVar bound to a union (or type equivalent to a union) where we also exhibit similar issues with reachability and narrowing:
from typing import assert_never, Literal
def f[T: bool](x: T) -> T:
match x:
case True:
return x
case False:
return x
case _:
reveal_type(x) # T@f & ~Literal[True] & ~Literal[False]
assert_never(x) # false-positive error
def g[T: Literal["foo", "bar"]](x: T) -> T:
match x:
case "foo":
return x
case "bar":
return x
case _:
reveal_type(x) # T@g & ~Literal["foo"] & ~Literal["bar"]
assert_never(x) # false-positive error
def h[T: int | str](x: T) -> T:
if isinstance(x, int):
return x
elif isinstance(x, str):
return x
else:
reveal_type(x) # T@h & ~int & ~str
assert_never(x) # false-positive errorOriginally posted by @AlexWaygood in astral-sh/ruff#21130 (review)