Python 2.1b1 dumps core on list compr.

[complex]

BPO	409230
Nosy	@mwhudson, @tim-one
Files	compile_patch: Patch to fix the bug

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2001-03-19.20:43:03.000>
created_at = <Date 2001-03-16.22:01:48.000>
labels = ['interpreter-core']
title = 'Python 2.1b1 dumps core on list compr.'
updated_at = <Date 2001-03-19.20:43:03.000>
user = 'https://bugs.python.org/complex'

bugs.python.org fields:

activity = <Date 2001-03-19.20:43:03.000>
actor = 'jhylton'
assignee = 'jhylton'
closed = True
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2001-03-16.22:01:48.000>
creator = 'complex'
dependencies = []
files = ['21']
hgrepos = []
issue_num = 409230
keywords = []
message_count = 7.0
messages = ['3889', '3890', '3891', '3892', '3893', '3894', '3895']
nosy_count = 5.0
nosy_names = ['mwh', 'tim.peters', 'jhylton', 'moshez', 'complex']
pr_nums = []
priority = 'high'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue409230'
versions = []

[complex]

Hi!

Python 2.1b1 dumps core when executing the following
statement:

print [[y for y in [x,x+1]] for x in [1,3]]

(Should print: [[1,2],[3,4]])

The problem may be related to variable scope resolving
code, because python reports "unknown scope for _[2] in
?(0)" before dumping core. This bug makes impossible to
use a list comprehension as the expression field of
another one.

-Complex-

[mwhudson]

Logged In: YES
user_id=6656

this is a dup of

[ bpo-406049 ] crash on nested listcomps

so someone with appropriate privilege should mark it as such.

[tim-one]

Logged In: YES
user_id=31435

Assigned to Jeremy. Boosted priority. Note that mwh says
this is a dup of 406049 (but this is clearly not the same
test case). Whatever, I confirmed that this specific case
still crashes.

Fatal Python error: unknown scope for _[2] in ?(0) in
<stdin>

[mwhudson]

Logged In: YES
user_id=6656

Well, no, it's not the same test case, but it is the same
problem. It also doesn't crash if you apply patch bpo-406076,
which I wrote to fix bpo-406049.

[moshez]

Logged In: YES
user_id=11645

Here is a patch to fix the problem.

[jhylton]

Logged In: YES
user_id=31392

This patch is incorrect. The root of the problem is that
the symbol table does not have the correct entry for the
nested list comp. The solution must address the symbol
table problem.

[jhylton]

Logged In: YES
user_id=31392

Fixed in rev. 2.187 of compile.c