R1732(consider-using-with): Regression on contextlib.ExitStack

[romainletendart]

Steps to reproduce

Using exit_stack.enter_context() within a with contextlib.ExitStack() as exit_stack block, I think we shouldn't have any R1732(consider-using-with) errors. At least, no errors were raised under pylint==2.8.3.

Given a file test.py:

import contextlib


def get_serial_number():
    with contextlib.ExitStack() as stack:
        location = stack.enter_context(open('/sys/firmware/devicetree/base/hwid,location', 'r'))
        year = stack.enter_context(open('/sys/firmware/devicetree/base/hwid,year', 'r'))
        week = stack.enter_context(open('/sys/firmware/devicetree/base/hwid,week', 'r'))
        genid = stack.enter_context(open('/sys/firmware/devicetree/base/hwid,genid', 'r'))
        sn = stack.enter_context(open('/sys/firmware/devicetree/base/hwid,sn', 'r'))

        return (
            location.read().rstrip('\x00')
            + year.read()[2:].rstrip('\x00')
            + week.read().rstrip('\x00')
            + genid.read().rstrip('\x00')
            + sn.read().rstrip('\x00')
        )

Current behavior

Result of pylint test.py:

************* Module test
test.py:6: [R1732(consider-using-with), get_serial_number] Consider using 'with' for resource-allocating operations
test.py:7: [R1732(consider-using-with), get_serial_number] Consider using 'with' for resource-allocating operations
test.py:8: [R1732(consider-using-with), get_serial_number] Consider using 'with' for resource-allocating operations
test.py:9: [R1732(consider-using-with), get_serial_number] Consider using 'with' for resource-allocating operations
test.py:10: [R1732(consider-using-with), get_serial_number] Consider using 'with' for resource-allocating operations

-------------------------------------------------------------------
Your code has been rated at 4.44/10 (previous run: -2.50/10, +6.94)

Expected behavior

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

pylint --version output

pylint 3.0.0-a4
astroid 2.6.2
Python 3.8.9 (default, Apr 19 2021, 08:40:21) 
[GCC 10.2.0]

The issue is the same with:

pylint 2.9.3
astroid 2.6.2
Python 3.8.9 (default, Apr 19 2021, 08:40:21) 
[GCC 10.2.0]

However, no issues with:

pylint 2.8.3
astroid 2.5.6
Python 3.8.9 (default, Apr 19 2021, 08:40:21) 
[GCC 10.2.0]

[Pierre-Sassoulas]

Thank you for opening the issue, I agree with you you should not have a warning here.

[DudeNr33]

I will look into this. I was not aware of the contextlib.ExitStack.enter_context() method.
This should be probably treated in a special way. I wonder if there are any other methods in the standard library that do similar things and should be considered as well.

[cdce8p]

I wonder if there are any other methods in the standard library that do similar things and should be considered as well.

Probably contextlib.AsyncExitStack.enter_async_context
https://docs.python.org/3/library/contextlib.html#contextlib.AsyncExitStack.enter_async_context

[DudeNr33]

Thanks @cdce8p.
This led me to realize that the whole consider-using-with check does not check asnychronous context managers at all.
A quick search over the Github repo of CPython shows that the standard library only has async context managers in form of the various locks of asyncio.locks and in asyncio.events.AbstractServer.