cannot detect and python interpreters; reopening of #5455

My system still cannot detect instances of the python interpreter. This is a re-opening of bug 5455 which was closed and locked for inactivity. Sorry for the delay.

Environment data

• VS Code version: 1.36.1
• Extension version (available under the Extensions sidebar): 2019.6.24221
• OS and version: Mac OS Mojave 10.14.5
• Python version (& distribution if applicable, e.g. Anaconda): Python 3.7
• Type of virtual environment used (N/A | venv | virtualenv | conda | …): virtualenv
• Relevant/affected Python packages and their versions: All
• Jedi or Language Server? (i.e. what is "python.jediEnabled" set to; more info #3977): None

Expected behaviour

Python interpreters are detected

Actual behaviour

Python interpreters are NOT detected

Steps to reproduce:

1. Create python package
2. Create a virtualenv in package
3. Launch score
4. Attempt to select interpreter

I used the final version of interpreterInfo.py from #5455 to gather these logs

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

[log.log](https://github.com/microsoft/vscode-python/files/3393584/log.log)

Output from Console under the Developer Tools panel (toggle Developer Tools on under Help; turn on source maps to make any tracebacks be useful by running Enable source map support for extension debugging)

[devTools.log](https://github.com/microsoft/vscode-python/files/3393587/devTools.log)

[mrbell321]

Ah-HA! That was it! I don’t know why grep didn’t find this… I don’t remember ever creating this file and there’s a copy in several projects, so it was probably cloned from something.

Thanks for walking me through this!

[mrbell321]

I did a bit of digging through minified extension.js javascript and found where python is being called. The stderr stream is being merged to std out so JS is trying to JSON.parse an error message(you probably already knew this part). So I set about trying to re-create the problem. When I run from the command line: /Users/tylerbell/code/TraceUpdater/venv/bin/python3.7 -W '"once' /Users/tylerbell/.vscode/extensions/ms-python.python-2019.6.24221/pythonFiles/interpreterInfo.py the response matches the error I am seeing: Invalid -W option ignored: invalid action: '"once' {"versionInfo": [3, 7, 3, "final"], "sysPrefix": "/Users/tylerbell/code/TraceUpdater/venv/bin/..", "version": "3.7.3 (default, Mar 27 2019, 09:23:15) \n[Clang 10.0.1 (clang-1001.0.46.3)]", "is64Bit": true}

Since the extension.js merges the stderr into stdout, it tries to parse everything as JSON and obviously fails when there is something not JSON, like an error message.

So the root cause question is, why is vscode trying to set the warning level to `‘"once’. The javascript is too obfuscated for me to follow.

The other question is, if you’re attempting to parse output as JSON, why would you merge in stderr? Seems like a recipe for failure.(but then again, silent passing could be worse)

I did manage to hack my way past the problem by changing the offending javascript to: const t = await this.procService.exec(this.pythonPath, [e], { mergeStdOutErr: false }).then(e => e.stdout.trim());

However, other vscode/python operations have similar issues. This is what I see when trying to debug my code: cd /Users/tylerbell/code/TraceUpdater ; env 'PYTHONPATH=$PTYHONPATH:' 'PYTHONWARNINGS="once' PYTHONIOENCODING=UTF-8 PYTHONUNBUFFERED=1 /Users/tylerbell/code/TraceUpdater/venv/bin/python3.7 /Users/tylerbell/.vscode/extensions/ms-python.python-2019.6.24221/pythonFiles/ptvsd_launcher.py --default --client --host localhost --port 52098 /Users/tylerbell/code/TraceUpdater/.vscode/launch.json

Note 'PYTHONWARNINGS="once' and the misspelled 'PYTHONPATH=$PTYHONPATH:'

I do not see these errors when launching loading my venv from the command line and launching the app and pycharm doesn’t have these issues either. it seems specific to vscode and/or the python plugin.