#10560 Broke `python.exe pip.whl/pip install`

[indygreg]

Description

#10560 broke python.exe /path/to/pip.whl/pip install on Windows.

I believe this is a side-effect of using os.path.basename(sys.argv[0]) == "pip" to attempt to check for direct pip invocations. Unfortunately, the new logic fails to handle the special case where python <wheel>/<module> can execute a module in a wheel file.

The python <wheel>/<module> syntax and behavior inside the interpreter with respect to sys.argv is a bit wonky. And using this syntax is probably an edge case. While I think the new behavior is incorrect, I'm unsure whether it is worth anyone's time to fix.

Expected behavior

python.exe /path/to/pip.whl/pip should work.

pip version

22.1.1

Python version

3.8-3.10

OS

Windows

How to Reproduce

python pip.whl/pip install

Output

executing C:\Users\RUNNER~1\AppData\Local\Temp\python-build-9rosg__z\out\python\install\python.exe D:\a\python-build-standalone\python-build-standalone\build\pip-22.1.1-py3-none-any.whl\pip install --no-cache-dir --no-index D:\a\python-build-standalone\python-build-standalone\build\pip-22.1.1-py3-none-any.whl
Processing d:\a\python-build-standalone\python-build-standalone\build\pip-22.1.1-py3-none-any.whl
ERROR: To modify pip, please run the following command:
C:\Users\RUNNER~1\AppData\Local\Temp\python-build-9rosg__z\out\python\install\python.exe -m pip install --no-cache-dir --no-index D:\a\python-build-standalone\python-build-standalone\build\pip-22.1.1-py3-none-any.whl

### Code of Conduct

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[uranusjr]

If I recall correctly, this was mentioned in the initial fix (not that PR which fixed the fix) and decided to be an unfortunate compromise. Running pip directly from wheel was never an officially supported operation.

[indygreg]

Yeah, this is an esoteric execution mode: I understand not wanting to support it.

FWIW this broke python-build-standalone, which used this method because it was robust in the face of cross-compiling. See astral-sh/python-build-standalone@cd2a0ff. According to my commit message, I borrowed the idea from ensurepip. So presumably ensurepip was modified upstream to account for this change in behavior. So I guess I'll change to whatever ensurepip is doing now.

Thanks for your feedback.

[uranusjr]

Actually ensurepip has not upgraded to 22.1, so we’ll see 😛 Maybe we’ll need to somehow add a special case for this eventually.

In the meantime, an alternative is to use get-pip.py’s approach—use zipfile to write the pip directory inside the wheel to a temporary file, and run that instead.

[indygreg]

FWIW it appears PYTHONPATH=pip.whl python.exe -m pip install works. This is just doing what I was doing before, just without the new/fixed Windows self-update prevention logic interfering. But since this is unsupported, I may transition to the wheel/zip extract approach.