@overload is required when using @dispatch

[orenbenkiki]

Is there a way to type-check code that uses @dispatch?

For example, consider the following synthetic example code:

from multipledispatch import dispatch

@dispatch(int)
def foo(x: int) -> None:
    print('int')

@dispatch(str)
def foo(x: str) -> None:
    print('str')

foo(1)  # Prints 'int'.
foo('a')  # Prints 'str'.

When I try to type-check this code with mypy, I get error: 'overload' decorator expected, because mypy does not recognize the @dispatch decorator.

Adding @overload before each @dispatch would satisfy mypy. However, it raises a run time error saying You should not call an overloaded function.. This makes sense, as the semantics of @overload are "this is only a signature, the real body is elsewhere.".

It seems what is needed is for mypy to directly recognize @dispatch...?

[ilevkivskyi]

This looks related to #2904