gh-126084: Fix venvwlauncher to run pythonw

[chrullrich]

Fixes #126084

• Issue: pythonw.exe from venv in 3.13 always creates console window #126084

[ZeroIntensity]

This is user-facing, so it needs a NEWS entry, per the bot. Probably needs a test too.

Also, for future reference, don't force push--it makes the review process more difficult. Everything is squash merged at the end anyway.

[chrullrich]

That test works fine locally. What could be different about the CI environment?

[chrullrich]

So it's not the realpath(). I don't want to waste massive amounts of time and energy by probing around the CI environment and running the whole lot each time. Any suggestions?

[devdanzin]

Locally for me, _winapi.GetModuleFileName(0) always returns the path to the Python process that launched the subprocess. Would sys.executable work?

[chrullrich]

Locally for me, _winapi.GetModuleFileName(0) always returns the path to the Python process that launched the subprocess.

It is supposed to return the path to the executable for the current process.

Would sys.executable work?

No:

C:\Daten>pyv\x64\Scripts\python.exe
Python 3.13.0 (tags/v3.13.0:60403a5, Oct  7 2024, 09:38:07) [MSC v.1941 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys; print(sys.executable)
C:\Daten\pyv\x64\Scripts\python.exe
>>> import _winapi; print(_winapi.GetModuleFileName(0))
C:\Program Files\Python313\python.exe

When in a venv, sys.executable is the wrapper in the venv. I'm looking for the "real" Python in the installation that was used to create the venv.

One moment please ...

[chrullrich]

This one should work in release and debug, but I'm curious to see whether it works in the GIL-less builds.

[Update: It does. The specific requirement is that the "w" immediately follows the "python" in the file name.]

[zooba]

Thanks for finding and fixing this! What a silly mistake (probably mine...)

[miss-islington-app]

Thanks @chrullrich for the PR, and @zooba for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @chrullrich and @zooba, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 802d405ff1233a48004a7c9b302baa76291514d1 3.12

[bedevere-app]

GH-126142 is a backport of this pull request to the 3.13 branch.

[zooba]

Doesn't apply to 3.12, only 3.13.