Aug 30, 2023 · Aug 16, 2023 · Aug 16, 2023 · Aug 29, 2023 · Aug 29, 2023
diff --git a/mypy/messages.py b/mypy/messages.py
            code=codes.OVERRIDE,
        )

        original = get_proper_type(original)
        override = get_proper_type(override)
        if (
            isinstance(original, Instance)
            and isinstance(override, Instance)
            and override.type.fullname == "typing.AsyncIterator"
            and original.type.fullname == "typing.Coroutine"
            and len(original.args) == 3
            and original.args[2] == override
        ):
            self.note(f'Consider declaring "{name}" in {target} without "async"', context)
            self.note(
                "See https://mypy.readthedocs.io/en/stable/more_types.html#asynchronous-iterators",
                context,
            )

    def override_target(self, name: str, name_in_super: str, supertype: str) -> str:
        target = f'supertype "{supertype}"'
        if name_in_super != name:
diff --git a/test-data/unit/check-async-await.test b/test-data/unit/check-async-await.test
 reveal_type(coro)  # N: Revealed type is "def () -> typing.AwaitableGenerator[builtins.int, None, None, typing.Generator[builtins.int, None, None]]"
 [builtins fixtures/async_await.pyi]
 [typing fixtures/typing-async.pyi]

 [case asyncIteratorInProtocol]
 from typing import AsyncIterator, Protocol

 class P(Protocol):
    async def launch(self) -> AsyncIterator[int]:
        raise BaseException

 class Launcher(P):
    def launch(self) -> AsyncIterator[int]:  # E: Return type "AsyncIterator[int]" of "launch" incompatible with return type "Coroutine[Any, Any, AsyncIterator[int]]" in supertype "P" \
                                             # N: Consider declaring "launch" in supertype "P" without "async" \
                                             # N: See https://mypy.readthedocs.io/en/stable/more_types.html#asynchronous-iterators
        raise BaseException

 [builtins fixtures/async_await.pyi]
 [typing fixtures/typing-async.pyi]
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1310,6 +1310,22 @@ def return_type_incompatible_with_supertype(
		code=codes.OVERRIDE,
		)

		original = get_proper_type(original)
		override = get_proper_type(override)
		if (
		isinstance(original, Instance)
		and isinstance(override, Instance)
		and override.type.fullname == "typing.AsyncIterator"
		and original.type.fullname == "typing.Coroutine"
		and len(original.args) == 3
		and original.args[2] == override
		):
		self.note(f'Consider declaring "{name}" in {target} without "async"', context)
		self.note(
		"See https://mypy.readthedocs.io/en/stable/more_types.html#asynchronous-iterators",
		context,
		)

		def override_target(self, name: str, name_in_super: str, supertype: str) -> str:
		target = f'supertype "{supertype}"'
		if name_in_super != name:
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1021,3 +1021,19 @@ def coro() -> Generator[int, None, None]:
		reveal_type(coro) # N: Revealed type is "def () -> typing.AwaitableGenerator[builtins.int, None, None, typing.Generator[builtins.int, None, None]]"
		[builtins fixtures/async_await.pyi]
		[typing fixtures/typing-async.pyi]

		[case asyncIteratorInProtocol]
		from typing import AsyncIterator, Protocol

		class P(Protocol):
		async def launch(self) -> AsyncIterator[int]:
		raise BaseException

		class Launcher(P):
		def launch(self) -> AsyncIterator[int]: # E: Return type "AsyncIterator[int]" of "launch" incompatible with return type "Coroutine[Any, Any, AsyncIterator[int]]" in supertype "P" \
		# N: Consider declaring "launch" in supertype "P" without "async" \
Copy link Member sobolevnAug 29, 2023 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Shouldn't it instead say: "consider adding`async` to`def lauch()`"? Because in my experience, AsyncIterators are way more common with`async def` rather than regular`def` Copy link ContributorAuthor ikonstAug 29, 2023• edited Loading Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Ehh, this is confusing :\| The 'problem' here should really be reported on this line: `class P(Protocol):!> async def launch(self) -> AsyncIterator[int]: raise BaseException` but we don't put notices proactively on declarations that smell funny, or do we? The error on the derived`Launcher.launch` gives us the excuse to make a notice. What we want to say is "listen, we must error on`Launcher.launch`, but`Launcher.launch` is probably fine, consider changing the base declaration instead".
		# N: See https://mypy.readthedocs.io/en/stable/more_types.html#asynchronous-iterators
		raise BaseException

		[builtins fixtures/async_await.pyi]
		[typing fixtures/typing-async.pyi]