Iterable Unpacking is destructive on argument

[simon-grantham]

Bug report

Using the binary asterisk operator before a zip object causes modification of the zip object itself.

Python 3.12.3 (main, Aug 31 2026, 10:18:26) [GCC 13.3.0] on linux
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>>> tmp1 = [1,2,3]
>>> tmp2 = [4,5,6]
>>> tmp = zip(tmp1,tmp2)
>>> print(tmp)
<zip object at 0x7bec69641340>
>>> print(list(tmp))
[(1, 4), (2, 5), (3, 6)]
>>> print(*tmp)

>>> print(list(tmp))
[]
>>> print(tmp)
<zip object at 0x7bec69641340>
>>>

CPython versions tested on:

3.12

Operating systems tested on:

Linux

[ericvsmith]

You've consumed the zip object when you called list on it. Here's an example, without unpacking:

>>> tmp1 = [1,2,3]
>>> tmp2 = [4,5,6]
>>> tmp = zip(tmp1, tmp2)
>>> print(tmp)
<zip object at 0x6fffffd3a600>
>>> print(list(tmp))
[(1, 4), (2, 5), (3, 6)]
>>> print(list(tmp))
[]
>>>