Erroneous 'list comprehension redefines' in Python 2.7 pyflakes 0.6.1 about pyflakes

[pyflakes-bot]

Original comment by icordasc (@sigmavirus24?) on Launchpad:

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I couldn't reproduce this with the attached file.

[pyflakes-bot]

Original comment by bistromathic1 on Launchpad:

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This problem seems to occur when a dummy variable name in a generator expression, a dict comprehension, or a set comprehension is then reused in a list comprehension, for example:

a = [1, 2, 3, 4, 5, 6]

b = (i + 1 for i in a)
c = [i + 2 for i in b]

print(c)

The pyflakes output is:

test-1.py:4: list comprehension redefines 'i' from line 3

I only tried this in python 3.2.

[pyflakes-bot]

Original comment by florent.x (@florentx?) on Launchpad:

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actually, this should not report redefinition of variable for:

• generator expressions
• dict comprehensions
• set comprehensions

Only the list comprehension leaks its variable, and only with Python 2.x.
(Though we'll keep reporting the warning for 3.x as well)

[pyflakes-bot]

Original comment by florent.x (@florentx?) on Launchpad:

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This should fix it.

https://code.launchpad.net/~pyflakes-dev/pyflakes/1112067-comprehension-scope/+merge/147264

[pyflakes-bot]

Original comment by danken on Launchpad:

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I'm not sure it's the very same bug, but pylakes 0.6.1 (python 2.7.3) considers the following as having a redefinition of x:

if False:
x = 1
else:
[x for x in [1]]

[pyflakes-bot]

Original comment by florent.x (@florentx?) on Launchpad:

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I'm not sure it's the very same bug, but pylakes 0.6.1 (python 2.7.3) considers the following as having a redefinition of x:

if False:
x = 1
else:
[x for x in [1]]

this last one is a different bug, it should be reported separately.

[pyflakes-bot]

Original comment by florent.x (@florentx?) on Launchpad:

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The fix for this second bug was added to the same branch:
https://code.launchpad.net/~pyflakes-dev/pyflakes/1112067-comprehension-scope/+merge/147264