Interpreter error when running a script under debugger control

[nirai]

BPO	3415
Nosy	@birkenfeld, @amauryfa
Superseder	bpo-2378: UnboundLocalError when trying to raise exceptions inside execfile

^{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 2008-07-21.09:29:43.518>
created_at = <Date 2008-07-19.05:32:34.369>
labels = ['interpreter-core', 'type-bug']
title = 'Interpreter error when running a script under debugger control'
updated_at = <Date 2008-07-21.09:29:43.456>
user = 'https://bugs.python.org/nirai'

bugs.python.org fields:

activity = <Date 2008-07-21.09:29:43.456>
actor = 'amaury.forgeotdarc'
assignee = 'jhylton'
closed = True
closed_date = <Date 2008-07-21.09:29:43.518>
closer = 'amaury.forgeotdarc'
components = ['Interpreter Core']
creation = <Date 2008-07-19.05:32:34.369>
creator = 'nirai'
dependencies = []
files = []
hgrepos = []
issue_num = 3415
keywords = []
message_count = 3.0
messages = ['70005', '70013', '70099']
nosy_count = 4.0
nosy_names = ['jhylton', 'georg.brandl', 'amaury.forgeotdarc', 'nirai']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = None
status = 'closed'
superseder = '2378'
type = 'behavior'
url = 'https://bugs.python.org/issue3415'
versions = ['Python 2.6', 'Python 3.0']

[nirai]

Interpreter error results in erroneous exception when running a script
under debugger control.

Full repro description:
On Windows System, try to run idle.py under the inspection of pdb.py.
Note that you must set a breakpoint somewhere otherwise pdb will not
trace the script and the issue will not surface.

You should get the bad exception in line 295 of multicall.py

Python complains that a local variable has been used before being
declared while in effect it has been a couple of lines before that point.

Nir

[birkenfeld]

For reference, here is the output of the pdb session:

gbr@lap ~/devel/python> ./python Lib/pdb.py Lib/idlelib/idle.py
> /home/gbr/devel/python/Lib/idlelib/idle.py(1)<module>()
-> try:
(Pdb) break multicall.py:300
***  'multicall.py' not found from sys.path
(Pdb) break idle.py:10
Breakpoint 1 at /home/gbr/devel/python/Lib/idlelib/idle.py:10
(Pdb) c
Traceback (most recent call last):
  File "/home/gbr/devel/python/Lib/pdb.py", line 1275, in main
    pdb._runscript(mainpyfile)
  File "/home/gbr/devel/python/Lib/pdb.py", line 1192, in _runscript
    self.run(statement)
  File "/home/gbr/devel/python/Lib/bdb.py", line 366, in run
    exec cmd in globals, locals
  File "<string>", line 1, in <module>
  File "Lib/idlelib/idle.py", line 21, in <module>
    idlelib.PyShell.main()
  File "/home/gbr/devel/python/Lib/idlelib/PyShell.py", line 1396, in main
    shell = flist.open_shell()
  File "/home/gbr/devel/python/Lib/idlelib/PyShell.py", line 275, in
open_shell
    self.pyshell = PyShell(self)
  File "/home/gbr/devel/python/Lib/idlelib/PyShell.py", line 816, in
__init__
    OutputWindow.__init__(self, flist, None, None)
  File "/home/gbr/devel/python/Lib/idlelib/OutputWindow.py", line 16, in
__init__
    EditorWindow.__init__(self, *args)
  File "/home/gbr/devel/python/Lib/idlelib/EditorWindow.py", line 108,
in __init__
    self.text = text = MultiCallCreator(Text)(
  File "/home/gbr/devel/python/Lib/idlelib/MultiCall.py", line 294, in
MultiCallCreator
    class MultiCall (widget):
  File "/home/gbr/devel/python/Lib/idlelib/MultiCall.py", line 295, in
MultiCall
    assert issubclass(widget, Tkinter.Misc)
NameError: free variable 'widget' referenced before assignment in
enclosing scope
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> /home/gbr/devel/python/Lib/idlelib/MultiCall.py(295)MultiCall()
-> assert issubclass(widget, Tkinter.Misc)
(Pdb) 

I *think* we had some similar issue with trace functions and class
scopes in the past, but can't remember where.

[amauryfa]

This issue is a duplicate of bpo-2378; the patch attached there
corrects this problem. I will commit it tonight.