| msg63856 - (view) |
Author: Jerry Seutter (jerry.seutter) *  |
Date: 2008-03-18 02:55 |
| Found a bug when trying to integrate figleaf coverage into trunk. I have ripped the code down to the smallest subset that still causes the behaviour. The code works on the latest release of Python 2.5 but is broken on trunk. It comes in two files. The first is the caller (figleaf): import os import sys def foo(f, e, o): pass sys.settrace(foo) import __main__ execfile('test_broken.py', __main__.__dict__) The second file is the test (test_broken.py): # This code breaks on trunk def test_foo(): class CustomException(Exception): pass class SomeClass: def foo(self): raise CustomException # The error only appears with enough nested blocks. if (True == True): try: raise IOError except CustomException: pass It should raise IOError. When run, it gives the following output: jerry-seutters-computer:~/code/python/core_wierd_bug_minimal jseutter$ ../core/python.exe figleaf Traceback (most recent call last): File "figleaf", line 10, in execfile('test_broken.py', __main__.__dict__) File "test_broken.py", line 18, in test_foo() File "test_broken.py", line 15, in test_foo except CustomException: UnboundLocalError: local variable 'CustomException' referenced before assignment [10019 refs] |
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| msg66575 - (view) |
Author: Pedro Werneck (werneck) |
Date: 2008-05-10 19:54 |
| Just note the error happens even without the try/except block inside the 'if' statement. |
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| msg66662 - (view) |
Author: Nikolas Coukouma (nikolasco) |
Date: 2008-05-11 20:21 |
| I can't reproduce this with r63075... |
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| msg66665 - (view) |
Author: Pedro Werneck (werneck) |
Date: 2008-05-11 20:45 |
| I get it with r63075, r63085, on Linux. |
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| msg66674 - (view) |
Author: Nikolas Coukouma (nikolasco) |
Date: 2008-05-11 21:34 |
| Apologies, I didn't run the test case correctly; I do get the error as reported |
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| msg68554 - (view) |
Author: alejandro david weil (tenuki) |
Date: 2008-06-22 02:38 |
| Shorter trigger code.. |
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| msg68555 - (view) |
Author: alejandro david weil (tenuki) |
Date: 2008-06-22 02:59 |
| Some debugging helper code and my conclutions of one work day: debughelper.tgZ: -test_broken1/2.py one does triggers the bug, the other doesn't) -rtest.sh executes boths and compares its outputs -frameobject.c.diff applied to Objects/frameobject.c, adds some debug info. What I found: 1. The CustomException is disappearing from locals() 2. PyFrame_FastToLocals() (from that .c file) is updating the locals, and removing that exception from there. 3. In the failing case this code: if (deref) { assert(PyCell_Check(value)); value = PyCell_GET(value); } is returning value==NULL. Don't know why that happens. But you could inspect out1.txt/out2.txt made with rtest.sh, and could discover something.. |
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| msg68613 - (view) |
Author: Amaury Forgeot d'Arc (amaury.forgeotdarc) * |
Date: 2008-06-23 07:34 |
| The problem seems to have been introduced by r53954. |
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| msg68617 - (view) |
Author: Amaury Forgeot d'Arc (amaury.forgeotdarc) * |
Date: 2008-06-23 08:54 |
| The problem is in PyFrame_LocalsToFast. (As I understand it: "Locals" refers to the locals() dictionary of the frame; "Fast" refers to an optimization where local variables are stored in an array. Each call to locals() or the trace function normalizes data by copying the Fast array into the Locals dictionary; with sys.settrace, the user may modify the locals, so the inverse transformation is done after each call to the trace function) When defining a class, PyFrame_FastToLocals does not copy the free variables from enclosing scopes. This is the goal of r53954 "Do not copy free variables to locals in class namespaces". When executing code in the class body, the sys.settrace function is called with this reduced set of locals(). The problem is that PyFrame_LocalsToFastdoes does not have the same test, and uses the locals() to update (and clear) the free variables as well. I attach a patch that makes PyFrame_LocalsToFast symmetric to PyFrame_FastToLocals: in the case of a class statement, do not update the free variables. |
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| msg70122 - (view) |
Author: Amaury Forgeot d'Arc (amaury.forgeotdarc) * |
Date: 2008-07-21 22:01 |
| Committed as r65177. |
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