Issue1412

The callback passed to sys.settrace is (sometimes) called with a bad 3rd
argument when an exception occurs.

According to
http://docs.python.org/library/sys.html

when there is an exception, arg is a tuple with 3 values.
In this case arg is

(<type 'exceptions.GeneratorExit'>, None, null)

and accessing arg[2] causes an error.

IndexError: index out of range: 2

I am not sure but the fact that arg[2] is "null" and not "None" might be
linked.

This is the output with jython

Here foo
(<type 'exceptions.GeneratorExit'>, None, null)
Arg size= 3
(<type 'exceptions.IndexError'>, 'index out of range: 2', <traceback
object at 0x1>)
Arg size= 3
<traceback object at 0x1>
(<type 'exceptions.IndexError'>, 'index out of range: 2', <traceback
object at 0x2>)
Arg size= 3
<traceback object at 0x2>
Traceback (most recent call last):
  File "/home/andrea/foo/j.py", line 16, in <module>
    import threading
  File "/home/andrea/projects/java/jython2.5.0/Lib/threading.py", line
12, in <module>
    from traceback import print_exc as _print_exc
  File "/home/andrea/projects/java/jython2.5.0/Lib/traceback.py", line
5, in <module>
    import types
  File "/home/andrea/projects/java/jython2.5.0/Lib/types.py", line 54,
in <module>
    GeneratorType = type(g())
  File "/home/andrea/foo/j.py", line 7, in printTrace
    print arg[2]
IndexError: index out of range: 2

And this with python 2.6

Here foo
(<type 'exceptions.AttributeError'>, '_release_save', <traceback object
at 0xb7d48f2c>)
Arg size= 3
<traceback object at 0xb7d48f2c>
(<type 'exceptions.AttributeError'>, '_acquire_restore', <traceback
object at 0xb7d48fcc>)
Arg size= 3
<traceback object at 0xb7d48fcc>
(<type 'exceptions.AttributeError'>, '_is_owned', <traceback object at
0xb7d48f04>)
Arg size= 3
<traceback object at 0xb7d48f04>
(<type 'exceptions.AttributeError'>, '_release_save', <traceback object
at 0xb7d48fa4>)
Arg size= 3
<traceback object at 0xb7d48fa4>
(<type 'exceptions.AttributeError'>, '_acquire_restore', <traceback
object at 0xb7d48f7c>)
Arg size= 3
<traceback object at 0xb7d48f7c>
(<type 'exceptions.AttributeError'>, '_is_owned', <traceback object at
0xb7d48fcc>)
Arg size= 3
<traceback object at 0xb7d48fcc>
Error caught

I've analyzed it a bit more and here is my result

http://article.gmane.org/gmane.comp.lang.jython.user/8055

Fix checked into rev6628:
http://jython.svn.sourceforge.net/viewvc/jython?view=rev&revision=6628

Thanks to Andrea for Patch.

We should add a regression test for this.

This is proving tough to get into a unit test today, assigning it to
myself to give it a try another day.

Closing as this is fixed and I haven't gotten around to putting a test in place for too long.