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never-union (RUF020)#

Fix is always available.

What it does#

Checks for uses of typing.NoReturn and typing.Never in union types.

Why is this bad?#

typing.NoReturn and typing.Never are special types, used to indicate that a function never returns, or that a type has no values.

Including typing.NoReturn or typing.Never in a union type is redundant, as, e.g., typing.Never | T is equivalent to T.

Example#

from typing import Never


def func() -> Never | int: ...

Use instead:

def func() -> int: ...

References#