Invalid Overload

What it does

Checks for various invalid @overload usages.

Why is this bad?

The @overload decorator is used to define functions and methods that accepts different combinations of arguments and return different types based on the arguments passed. This is mainly beneficial for type checkers. But, if the @overload usage is invalid, the type checker may not be able to provide correct type information.

Examples

Single overload

from typing import overload


@overload
def foo(x: int) -> int: ...  # error
def foo(x: int | None) -> int | None:
    return x

Missing implementation

from typing import overload


@overload
def foo() -> None: ...  # error
@overload
def foo(x: int) -> int: ...

References

• Python documentation: @overload