False type inference: no-member in except*

[rkupke]

Bug description

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Sun Apr 30 11:15:39 2023
"""

# pylint: disable=W0104,W0107,C0115,C0199,C0116,C0103,W0106

import typing


try:
    try:
        ex_list = [ValueError("a"), ValueError("b"),  Exception("c")]
        raise ExceptionGroup("exceptions!", ex_list)
    except* ValueError as exc:
        print(repr(exc))

        typing.reveal_type(exc)
        assert isinstance(exc, ExceptionGroup)
        assert hasattr(exc, "message")
        assert hasattr(exc, "exceptions")

        # E1101:no-member: 25,8: Instance of 'ValueError' has no 'message' member
        exc.message

        # E1101:no-member: 28,8: Instance of 'ValueError' has no 'exceptions' member
        exc.exceptions

        # E1101:no-member: 31,8: Instance of 'ValueError' has no 'message' member
        typing.cast(ExceptionGroup, exc).message

        pass
except ExceptionGroup as exc:
    print(repr(exc))
    exc.message  # this works
    exc.exceptions
    pass

Configuration

No response

Command used

pylint Schreibtisch/test.py

Pylint output

************* Module test
Schreibtisch/test.py:25:8: E1101: Instance of 'ValueError' has no 'message' member (no-member)
Schreibtisch/test.py:28:8: E1101: Instance of 'ValueError' has no 'exceptions' member (no-member)
Schreibtisch/test.py:31:8: E1101: Instance of 'ValueError' has no 'message' member (no-member)

------------------------------------------------------------------
Your code has been rated at 2.50/10 (previous run: 2.50/10, +0.00)

Expected behavior

Type of exc should be inferred as ExceptionGroup

Pylint version

pylint 2.17.4
astroid 2.15.6
Python 3.11.2 (main, Mar 13 2023, 12:18:29) [GCC 12.2.0]

OS / Environment

uname -a
Linux odysseus 6.1.0-12-arm64 #1 SMP Debian 6.1.52-1 (2023-09-07) aarch64 GNU/Linux

Additional dependencies

No response

[mbyrnepr2]

Thank you for reporting the issue. The fix for #8985 will possibly also fix this.

[ejep520]

As of 3.11, BaseException now has an optional __notes__ attribute. It is added to an instance of the exception when an instance runs the .add_note() method. I've made some new error classes that inherit from existing errors that insist on a string parameter at instantiation that can be added to itself via the .add_note() method. Unfortunately, Pylint says these classes don't have a __notes__ attribute.

Would this fall under the same issue, or is this a different issue? Thanks!

[AI0867]

As of 3.11, BaseException now has an optional __notes__ attribute. It is added to an instance of the exception when an instance runs the .add_note() method. I've made some new error classes that inherit from existing errors that insist on a string parameter at instantiation that can be added to itself via the .add_note() method. Unfortunately, Pylint says these classes don't have a __notes__ attribute.

Would this fall under the same issue, or is this a different issue? Thanks!

I would say that's a different issue. While the presented error is the same, this issue is about the actual type inferred in an except-star statement being incorrect. (in except* FooException as foo:, foo is actually an ExceptionGroup containing FooExceptions, not a FooException)
Your issue is about the fact that __notes__ is not inferred to be always present on subclasses of Exception that always populate it. (inferring that also seems like a lot more work)

[gpatel-fr]

As of 3.11, BaseException now has an optional __notes__ attribute. It is added to an instance of the exception when an instance runs the .add_note() method. I've made some new error classes that inherit from existing errors that insist on a string parameter at instantiation that can be added to itself via the .add_note() method. Unfortunately, Pylint says these classes don't have a __notes__ attribute.

Would this fall under the same issue, or is this a different issue? Thanks!

@AI0867 @ejep520

Maybe I miss something obvious, but I don't see this as a real issue.
This is a dynamic attribute, Python has a built-in method to access dynamic attribute: getattr.

So instead of writing
exc.__notes__, use ' '.join(getattr(exc, '__notes__',['']))
and pylint will be happy with it.
At least it works for me.