[issue8847] crash appending list and namedtuple

[Terry J. Reedy]

Terry J. Reedy <tjreedy at udel.edu> added the comment:

Running the exact same binary on winxp with an amd athlon processor,
I *did* get a crash after about 5 seconds. "python.exe has encountered a problem and needs to close.  We are sorry for the inconvenience."
Trying again with IDLE instead of the command window, I get the same message (for pythonw instead of python) and the shell restarts when I close the message.

Even though foo()+[1] correctly raises a TypeError, the reverse [1] + foo() very bizarrely produces a length 1 tuple whose bizarre member is supposedly an instance of a empty list [] with length 1

from collections import namedtuple
foo = namedtuple('foo', '')
a = [1] + foo()
b=a[0]
print (type(a), len(a), type(b), len(type(b)), type(type(b)))

# <class 'tuple'> 1 [] 1 <class 'list'>

([2]+foo() produces same output)

Other than the above, any attempt to do anything with b or type(b) that I tried crashes. I presume that this is due to attribute lookups on the invalid type(b) (or something like that), which type(b) must bypass. In particular, the OP's crash is due to trying to print the tuple which tries to print its member which looks for type(b).__str__ which crashes.

To anyone: investigating crashers like this is a lot easier with IDLE and an edit window than with the interactive command window.

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nosy: +tjreedy
resolution: works for me -> 

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue8847>
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