Wrong type hint for tracing Signal sequence

[stj]

Long story short

Type hints for tracing Signal contents look wrong.

Expected behaviour

mypy does not report an error when adding handlers to a signal object.

Actual behaviour

mypy reports an error of

error: List item 0 has incompatible type "Callable[[ClientSession, SimpleNamespace, TraceConnectionCreateEndParams], Coroutine[Any, Any, None]]"; expected "Callable[[TraceConfig], Awaitable[None]]"

Steps to reproduce

Run mypy over this snippet

import types

import aiohttp
import datadog

async def reuse_keepalive_connection(
    session: aiohttp.ClientSession,
    trace_config_ctx: types.SimpleNamespace,
    params: aiohttp.TraceConnectionReuseconnParams,
) -> None:
    """statsd counter; how often has a connection been reused"""
    datadog.statsd.increment("client.request.connection.reuse")

tracer = aiohttp.TraceConfig()
tracer.on_connection_reuseconn.extend([reuse_keepalive_connection])

Your environment

aiohttp 3.5.4
python 3.7.2
mypy 0.660

[aio-libs-bot]

GitMate.io thinks the contributor most likely able to help you is @asvetlov.

Possibly related issues are #401 (Signals), #1749 (Type hinting in code), #3230 (iter_chunks type annotation wrong), #3032 (Doc: signals), and #1309 (Client Tracing).

[asvetlov]

Fixed by #3596

[mvbrn]

The similar issue still appears for me:

class RequestLogger:
    async def _on_request_start(
        self,
        session: aiohttp.ClientSession,
        context: SimpleNamespace,
        params: aiohttp.TraceRequestStartParams,
    ) -> None:
        ...

    def make_trace_config(self):
        tc = aiohttp.TraceConfig()
        tc.on_request_start.append(self._on_request_start)
        return tc

results with:

 error: Argument 1 to "append" of "MutableSequence" has incompatible type "Callable[[ClientSession, SimpleNamespace, TraceRequestStartParams], Coroutine[Any, Any, None]]"; expected "Callable[[ClientSession, SimpleNamespace, <union: 15 items>], Awaitable[None]]"

Python 3.7.7
mypy 0.770

[asvetlov]

type annotation is reimplemented