Breakpoints in non-stdlib modules named io.py are always skipped

[ollie-bell]

Any breakpoint within a non-stdlib module named io.py will always be skipped.

e.g. consider the python package:

.
├── mypackage
│   ├── __init__.py
│   ├── io.py
│   └── main.py
└── pyproject.toml

# mypackage/io.py

def foo():
    return "hello from mypackage.io.foo"

# mypackage/main.py

from mypackage.io import foo


def main():
    return foo()


if __name__ == "__main__":
    main()

If you add a breakpoint inside mypackage.io.foo it will always be skipped, and you cannot step into that module.

Renaming the module to anything else fixes the issue.

PDB honour's breakpoints in that module (i.e. add breakpoint() in mypackage.io.foo and running python -m mypackage.main)

[eleanorjboyd]

How are you debugging? Are you using a config? Did you set the justMyCode to false?

[ollie-bell]

I have "debugpy.debugJustMyCode": false in my global vscode settings, other than that no special config, just the standard debug current file.

If I make a launch.json with "justMyCode": true then attempting to step into the call to foo() from mypackage.io gives the message:

With "justMyCode": false, attempting to step in weirdly puts me into some random part of the stdlib (I had no breakpoint set here)

... again, if change the name of mypackage.io module to anything else it works as expected.

The behaviour occurs regardless of whether mypackage is installed as editable or not.

Have tried launch config for both "Current File" and "Module", both behave the same:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python Debugger: Module",
            "type": "debugpy",
            "request": "launch",
            "module": "mypackage.main",
            "justMyCode": false
        },
        {
            "name": "Python Debugger: Current File",
            "type": "debugpy",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal",
            "justMyCode": false
        }
    ]
}

About Visual Studio Code:

Version: 1.96.2
Commit: fabdb6a30b49f79a7aba0f2ad9df9b399473380f
Date: 2024-12-19T10:22:47.216Z
Electron: 32.2.6
ElectronBuildId: 10629634
Chromium: 128.0.6613.186
Node.js: 20.18.1
V8: 12.8.374.38-electron.0
OS: Darwin arm64 24.1.0

[ollie-bell]

FWIW I have just tested this on a different machine (still macOS arm64) with completely fresh installs of Python and vscode... and I continue to observe this behaviour.