iscoroutinefunction doesn't work for partial bound methods

[pdewacht]

Bug report

iscoroutinefunction doesn't work for partial bound methods. Consider this example. The second assert fails.

import asyncio
import functools

class A:
    async def a(self, x, y):
        pass

assert asyncio.iscoroutinefunction(A().a)
assert asyncio.iscoroutinefunction(functools.partial(A().a, 1))

I found two related issues:

• Support functools.partial in inspect.is*function() checks #79071 fixed this for functions, but not for bound methods
• inspect.iscoroutinefunction / isgeneratorfunction / isasyncgenfunction can't handle partialmethod objects #82545 proposes to add support for partialmethod, but wouldn't fix this case

Your environment

• CPython versions tested on: Python 3.10.5
• Operating system and architecture: Debian unstable, amd64

[PurityLake]

This seems to be fixed in #67707

Can confirm assertion passes on main branch. Python version3.12.0a0.

[corona10]

This seems to be fixed in #67707

Yeah I double check that this issue was already fixed.

[graingert]

That's weird

[graingert]

Ah that's because the the parital of a bound method isn't going via while ismethod(f):, it passes inspect._signature_is_functionlike directly

>>> import functools
>>> class A:
...     async def a(self, x, y):
...         pass
... 
>>> A().a
<bound method A.a of <__main__.A object at 0x7f8219707a30>>
>>> import inspect
>>> inspect._signature_is_functionlike(A().a)
True
>>> A().a.__code__.co_flags
195
>>> 

>>> p = functools.partial(A().a)
>>> inspect.ismethod(p)
False
>>> m = functools._unwrap_partial(p)
>>> m
<bound method A.a of <__main__.A object at 0x7f8219707a30>>
>>> inspect.isfunction(m)
False
>>> inspect._signature_is_functionlike(m)
True