raising-non-exception False Positive

[dmtucker]

Steps to reproduce

"""example.py"""


class Error(Exception):
    """some error"""


def _foobar():
    exceptions = tuple([ValueError, TypeError])
    try:
        raise ValueError
    except exceptions as exc:  # pylint: disable=catching-non-exception
        # https://github.com/PyCQA/pylint/issues/1756
        exc = Error(exc)
        if exc:
            raise exc

Current behavior

$ pylint example.py
No config file found, using default configuration
************* Module example
E: 16,12: Raising a new style class which doesn't inherit from BaseException (raising-non-exception)

------------------------------------------------------------------
Your code has been rated at 4.44/10 (previous run: 4.44/10, +0.00)

Expected behavior

$ pylint example.py
No config file found, using default configuration

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

The if seems to be crucial to the repro. For example, this does NOT repro:

"""example.py"""


class Error(Exception):
    """some error"""


def _foobar():
    exceptions = tuple([ValueError, TypeError])
    try:
        raise ValueError
    except exceptions as exc:  # pylint: disable=catching-non-exception
        # https://github.com/PyCQA/pylint/issues/1756
        exc = Error(exc)
        raise exc

This also isn't an issue if #1756 isn't present:

"""example.py"""


class Error(Exception):
    """some error"""


def _foobar():
    try:
        raise ValueError
    except (ValueError, TypeError) as exc:
        exc = Error(exc)
        if exc:
            raise exc

pylint --version output

No config file found, using default configuration
pylint 1.9.3,
astroid 1.6.5
Python 2.7.5 (default, Jul 13 2018, 13:06:57)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)]

[dmtucker]

This repro is even simpler:

"""example.py"""


def _foobar():
    exceptions = tuple([ValueError, TypeError])
    try:
        raise ValueError
    except exceptions as exc:
        raise exc

$ pylint example.py
No config file found, using default configuration
************* Module example
E:  8,11: Catching an exception which doesn't inherit from Exception: exceptions (catching-non-exception)
E:  9, 8: Raising a new style class which doesn't inherit from BaseException (raising-non-exception)

--------------------------------------------------------------------
Your code has been rated at -6.67/10 (previous run: -6.67/10, +0.00)

[dmtucker]

I am able to reproduce on 2.1.1 also.