[New-bugs-announce] [issue2537] re.compile(r'((x|y+)*)*') should fail

Jason Orendorff report at bugs.python.org
Wed Apr 2 19:36:06 CEST 2008

New submission from Jason Orendorff <jason.orendorff at gmail.com>:

Below, the second regexp seems just as guilty as the first to me.

Python 2.5.1 (r251:54869, Apr 18 2007, 22:08:04) 
[GCC 4.0.1 (Apple Computer, Inc. build 5367)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> re.compile(r'((x|y)*)*')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
line 180, in compile
    return _compile(pattern, flags)
line 233, in _compile
    raise error, v # invalid expression
sre_constants.error: nothing to repeat
>>> re.compile(r'((x|y+)*)*')
<_sre.SRE_Pattern object at 0x18548>

I don't know if that error is to protect the sre engine from bad
patterns or just a courtesy to users.  If the former, it could be a
serious bug.

messages: 64865
nosy: jorendorff
severity: normal
status: open
title: re.compile(r'((x|y+)*)*') should fail
versions: Python 2.6

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