Author Jelle Zijlstra
Recipients Jelle Zijlstra
Date 2016-12-13.16:28:07
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Marked as misclassified Yes
Message-id <>
$ cat 
class BadError(Exception):
    def __init__(self):
        self.i = 0

    def __hash__(self):
        self.i += 1
        return self.i

e = BadError()
raise e from e
$ ./python.exe -V
Python 3.5.2+
$ ./python.exe 
Segmentation fault: 11

I have reproduced this with Python 3.3, 3.4, 3.5, and 3.6; I assume it's been present throughout the 3 series.

This is because print_exception_recursive in pythonrun.c keeps following the __cause__ chain, and here the exception is its own __cause__. It uses a set to ensure that it breaks cycles, but that doesn't help here because of the exception's incorrect __hash__ method.
Date User Action Args
2016-12-13 16:28:07Jelle Zijlstrasetrecipients: + Jelle Zijlstra
2016-12-13 16:28:07Jelle Zijlstrasetmessageid: <>
2016-12-13 16:28:07Jelle Zijlstralinkissue28962 messages
2016-12-13 16:28:07Jelle Zijlstracreate