Don't report multiple-statements for def + ellipsis

[mthuurne]

Code using type annotations often has no need for a function body and puts ellipsis (...) there to indicate that.

For example when using @overload:
(this was taken straight from PEP 484)

from typing import overload

@overload
def concat2(x: str, y: str) -> str: ...
@overload
def concat2(x: bytes, y: bytes) -> bytes: ...

Or when defining a protocol:
(when using a Python version before 3.8, you'll have to install typing_extensions and import Protocol from there)

from typing import Any, Protocol

class ComparableProto(Protocol):
    def __eq__(self, other: Any) -> bool: ...
    def __ne__(self, other: Any) -> bool: ...
    def __lt__(self, other: Any) -> bool: ...
    def __le__(self, other: Any) -> bool: ...
    def __gt__(self, other: Any) -> bool: ...
    def __ge__(self, other: Any) -> bool: ...

However, when using this syntax, PyLint 2.4.3 will report More than one statement on a single line (multiple-statements).

While it is technically correct that the ellipsis is a statement, it is used to indicate the absence of meaningful statements. So in my opinion it would be better to have a special case for not reporting the situation in which there are two statements, the first of which is def and the second of which is Ellipsis.

[PCManticore]

Yeah, I think we can exempt these situations.

[mthuurne]

Thanks!

[mthuurne]

On my PC, the fix works for Protocols, but for some reason not for functions/methods. [...]

Never mind; it wasn't working for Protocols either, I messed up my local testing. Also I didn't realize that the fix for this was committed on master and not on the 2.4 branch and therefore wouldn't be in the 2.4.4 release anyway.