pdb's longlist shows only decorator if that one contains a lambda

[gerritholl]

BPO	23832
Nosy	@gerritholl, @pablogsal, @iritkatriel

^{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 2020-09-16.14:43:30.740>
created_at = <Date 2015-03-31.20:35:12.690>
labels = ['type-bug', 'library']
title = "pdb's `longlist` shows only decorator if that one contains a lambda"
updated_at = <Date 2020-09-16.14:43:30.740>
user = 'https://github.com/gerritholl'

bugs.python.org fields:

activity = <Date 2020-09-16.14:43:30.740>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2020-09-16.14:43:30.740>
closer = 'pablogsal'
components = ['Library (Lib)']
creation = <Date 2015-03-31.20:35:12.690>
creator = 'Gerrit.Holl'
dependencies = []
files = []
hgrepos = []
issue_num = 23832
keywords = []
message_count = 3.0
messages = ['239749', '375776', '375798']
nosy_count = 3.0
nosy_names = ['Gerrit.Holl', 'pablogsal', 'iritkatriel']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue23832'
versions = ['Python 3.4']

[gerritholl]

When a decorater contains a lambda declaration, using the pdb command longlist will show only the definition of the decorator. The definition of the function itself is not shown:

cat mini.py

#!/usr/bin/python3.4

def foo(x, y=None):
    return x

@foo(foo, lambda a:a)
def spam():
0+0
1+1
1/0

spam()
$ python3.4 -mpdb mini.py                                                                                                                                               
> /tmp/mini.py(3)<module>()
-> def foo(x, y=None):
(Pdb) cont
Traceback (most recent call last):
  File "/usr/lib64/python3.4/pdb.py", line 1661, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib64/python3.4/pdb.py", line 1542, in _runscript
    self.run(statement)
  File "/usr/lib64/python3.4/bdb.py", line 431, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/tmp/mini.py", line 3, in <module>
    def foo(x, y=None):
  File "/tmp/mini.py", line 10, in spam
    1/0
ZeroDivisionError: division by zero
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> /tmp/mini.py(10)spam()
-> 1/0
(Pdb) longlist
  6     @foo(foo, lambda a:a)
(Pdb) 

The last line illustrates the problem. longlist should show the definition of spam, not just the decorator.

[iritkatriel]

I think this has been fixed by now, because I don't see the problem in Python 3.10:

python.bat -mpdb tmp1.py
Running Release|Win32 interpreter...
> c:\users\user\src\cpython\tmp1.py(2)<module>()
-> def foo(x, y=None):
(Pdb) c
Traceback (most recent call last):
  File "C:\Users\User\src\cpython\lib\pdb.py", line 1740, in main
    pdb._runscript(mainpyfile)
  File "C:\Users\User\src\cpython\lib\pdb.py", line 1609, in _runscript
    self.run(statement)
  File "C:\Users\User\src\cpython\lib\bdb.py", line 580, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "c:\users\user\src\cpython\tmp1.py", line 2, in <module>
    def foo(x, y=None):
  File "c:\users\user\src\cpython\tmp1.py", line 9, in spam
    1/0
ZeroDivisionError: division by zero
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> c:\users\user\src\cpython\tmp1.py(9)spam()
-> 1/0
(Pdb) longlist
  5     @foo(foo, lambda a:a)
  6     def spam():
  7         0+0
  8         1+1
  9  ->     1/0
(Pdb)

[iritkatriel]

pdb uses inspect.findsource for this, where this problem was fixed in bpo-1764286.

I believe this ticket can be closed.