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Pdb "commands" command with no bpnumber should use last available breakpoint #142834

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Pdb "commands" command with no bpnumber should use last available breakpoint#142834
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stdlibStandard Library Python modules in the Lib/ directorytype-bugAn unexpected behavior, bug, or error

Description

@cocolato
cocolato
opened on Dec 16, 2025

Bug report

Bug description:

According to the documentation:

With no bpnumber argument, commands refers to the last breakpoint set.

I think the intended meaning should be the last available breakpoint. However, when using the commands command without specifying a breakpoint number, if the most recently created breakpoint has been deleted, the current behavior throws an error stating "Breakpoint N already deleted".

main.py:

foo = 1
bar = 2
➜ ./python -m pdb main.py
> /cpython/main.py(2)<module>()
-> foo = 1
(Pdb) b 3    
Breakpoint 1 at /cpython/main.py:3
(Pdb) b 2
Breakpoint 2 at /cpython/main.py:2
(Pdb) clear 2
Deleted breakpoint 2 at /cpython/main.py:2
(Pdb) commands # should set command on breakpoint 1
*** cannot set commands: Breakpoint 2 already deleted

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

Activity

  1. cocolato
    added
    type-bugAn unexpected behavior, bug, or error
    on Dec 16, 2025

  2. johnslavik commented on Dec 16, 2025

    @johnslavik
    johnslavik
    on Dec 16, 2025
    Member

    @ZeroIntensity stdlib

  3. aisk
    added
    stdlibStandard Library Python modules in the Lib/ directory
    on Dec 16, 2025

  4. johnslavik commented on Dec 16, 2025

    @johnslavik
    johnslavik
    on Dec 16, 2025
    Member

    Good idea! Should it really be the last available breakpoint, or the last enabled breakpoint?

  5. johnslavik commented on Dec 17, 2025

    @johnslavik
    johnslavik
    on Dec 17, 2025
    Member

    Should it really be the last available breakpoint, or the last enabled breakpoint?

    cc @gaogaotiantian

  6. gaogaotiantian commented on Dec 17, 2025

    @gaogaotiantian
    gaogaotiantian
    on Dec 17, 2025
    Member

    Should it really be the last available breakpoint, or the last enabled breakpoint?

    I think it should be the last available breakpoint because it's totally valid to set commands on a disabled breakpoint. However, this is a very rare case already. I believe commands is used mostly either immediately after breakpoint, or explicitly on a numbered breakpoint. This specific difference won't be noticable to the majority of the users.

  7. gaogaotiantian
    added a commit that references this issue on Dec 20, 2025

    gh-142834: pdb commands command should use last available breakpoint (#…

    3cc5750
  8. cocolato
    added a commit that references this issue on Dec 22, 2025

    pythongh-142834: pdb commands command should use last available break…

    4fb952f
  9. cocolato
    closed this as completedon Dec 22, 2025
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