PowerShell script debugpy.ps1 incorrectly handles multiple arguments passed as an array

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Assessment

Difficulty
1/5
Estimated time
1-3 hours
Newbie friendliness
88/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
powershell, python
Domain
cli

Research direction

Start in the debugpy.ps1 wrapper, focusing on how its argument list is passed to the Python command in each OS branch. Reproduce the issue with the provided run.ps1 and test.py scripts, then verify that array arguments remain separate and produce the expected sys.argv output.

Written by the indexing model from the issue text.

Description

triage-needed

Description:

When using the PowerShell wrapper script debugpy.ps1 to debug a Python script that accepts multiple command-line arguments, the arguments are not properly passed through to the Python script when provided as an array.

Steps to Reproduce:

  1. Create a test Python script (test.py):
import sys
print(sys.argv)
  1. Create a PowerShell script (run.ps1):
$arg_list = @('arg1', 'arg2')
$file = "test.py"

& python $file $arg_list  # Works correctly
& debugpy $file $arg_list  # Fails - arguments are concatenated
  1. Run the PowerShell script:
.\run.ps1

Actual Result:

['test.py', 'arg1', 'arg2']
['test.py', 'arg1 arg2']

Expected Result:

['test.py', 'arg1', 'arg2']
['test.py', 'arg1', 'arg2']

Root Cause:
The current debugpy.ps1 script passes $args directly to the Python command without using splatting (@args). When an array is passed to the script, PowerShell's $args receives it as a single object rather than expanding it into multiple arguments.

Current code:

if ($os -eq [System.PlatformID]::Win32NT) {
    python $env:BUNDLED_DEBUGPY_PATH --listen 0 --wait-for-client $args
} else {
    python3 $env:BUNDLED_DEBUGPY_PATH --listen 0 --wait-for-client $args
}

Proposed Fix:
Use the splatting operator (@args) instead of $args to properly expand array arguments:

if ($os -eq [System.PlatformID]::Win32NT) {
    python $env:BUNDLED_DEBUGPY_PATH --listen 0 --wait-for-client @args
} else {
    python3 $env:BUNDLED_DEBUGPY_PATH --listen 0 --wait-for-client @args
}
Dominant language
TypeScript
Stars
181
Forks
126
Avg merge
2d 3h
Merged PRs (30d)
3

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