[Python-bugs-list] [ python-Bugs-418977 ] Access Violation in PyCell_Set

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Bugs item #418977, was updated on 2001-04-25 15:22
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Category: Python Interpreter Core
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Greg Chapman (glchapman)
Assigned to: Nobody/Anonymous (nobody)
Summary: Access Violation in PyCell_Set

Initial Comment:
While stepping through a program using the Pythonwin 
debugger, I got an access violation which appears to 
be taking place in PyCell_Set (I'm not using the debug 
libraries).  Specifically, it appears that the op 
parameter is NULL, so the PyCell_Check(op) results in 
the AV.  I believe the call stack at this point was:

  PyCell_Set
  dict_to_map
  PyFrame_LocalsToFast (line 366 of frameobject.c?)
  call_trace
  SET_LINENO (case of eval_code2)

Please let me know if it would be helpful to see the 
python file I was stepping through and I'll upload it.


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>Comment By: Martin v. Löwis (loewis)
Date: 2001-04-26 08:51

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There is a patch for this bug in
http://sourceforge.net/tracker/index.php?func=detail&aid=419176&group_id=5470&atid=305470

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Comment By: Martin v. Löwis (loewis)
Date: 2001-04-26 08:46

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It turns out that the error is caused by the tracing. The
example t2.py will cause this error in Python 2.1 even
without running under a debugger.

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Comment By: Greg Chapman (glchapman)
Date: 2001-04-26 05:19

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As requested, I've stripped down the code to a fairly 
simple test case.  There's a comment indicating the line on 
which the AV occurs (it occurs when you press the key to 
single step off that line to the next).  No AV occurs if 
you simply run the script under PythonWin.

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Comment By: Martin v. Löwis (loewis)
Date: 2001-04-26 00:19

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I think it would be definitely helpful to see the sources;
it would be even better if you could reduce them to a small
test case. Please attach them to this report.

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Comment By: Greg Chapman (glchapman)
Date: 2001-04-25 15:29

Message:
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I apologize -- I forgot to add that I'm using Python 2.1 
final (binaries downloaded from Sourceforge) and the latest 
win32_all binaries under Windows 2000.

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http://sourceforge.net/tracker/?func=detail&atid=105470&aid=418977&group_id=5470