Repository navigation
Pdb bug when using names that collide w/ aliases of breakpoints operations #111352
Closed as not planned
Description
Bug report
Bug description:
Using specific values as variable names in breakpoints leads to incorrect behaviour.
This seems to be because certain chars are used as aliases in pdb, i.e c is continue, p is print etc.
It is triggered when the following char is non-alpha-numeric, afaict.
MRE:
Python 3.9.5 (default, Sep 14 2021, 12:04:19)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> breakpoint()
--Return--
> <stdin>(1)<module>()->None
(Pdb) c = None
>>> c
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'c' is not defined
>>>
# I expect to still be in a breakpoint here, and for `c` to be `None`, but pdb has 'continued' execution instead.The same is true for other aliases, like q and p, which raise errors relating to their respective functions. (I have not tried all aliases).
CPython versions tested on:
3.9
Operating systems tested on:
Linux
Activity
AlexWaygood commentedon Oct 26, 2023
I can reproduce your results on Python 3.12, but the output is pretty different on
main(likely because of some changes @gaogaotiantian has been making to improve pdb):Running Debug|x64 interpreter... Python 3.13.0a1+ (heads/main:232465204e, Oct 17 2023, 15:23:17) [MSC v.1932 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> breakpoint() --Return-- > <python-input-0>(1)<module>()->None -> breakpoint() (Pdb) c = None *** Invalid argument: = None Usage: c(ont(inue)) (Pdb)gaogaotiantian commentedon Oct 26, 2023
Right, the fix just missed 3.12 because core devs were super busy before release :) We did not consider it as a "bug fix" so no backport was done. The PR is #103465.
The core issue is pdb parses
c = Noneas ac, orcontinuecommand += Noneargs, which is whatcmd.Cmd(pdb is a subclass of it) does. In the old pdb, there's no argument checking - extra arguments will just be ignored. Soc = Noneis strictly equivalent toc.We can backport the PR if we want, otherwise this should be marked done. We won't fix 3.9 of course, it does not take bug fixes anymore. The best we can do is to backport the fix to 3.11.
AlexWaygood commentedon Oct 26, 2023
Yeah, I think I agree that this is probably a new feature rather than a bugfix. So... wait for Python 3.13, I guess :)
Sorry we can't do better than that here @JosephSBoyle!