Python3 installer is broken on Windows

[juj]

I was unable to find the appropriate GitHub repository for the Windows installer, so reporting this here to get visibility somewhere at least.

Steps To Reproduce:

1. Visit python.org to download Python 3.11 for Windows:

2. Launch the installer, choose e.g. the following options (shouldn't matter much, except note to add Python to PATH):

3. After installation finishes, open a new command prompt, and type python3:

and press enter.

Observed: The Microsoft Store page pops up, asking the user to install Python 3.10:

Expected: The just installed python 3.11 interpreter should launch.

[juj]

As a workaround, looks like one can copy C:\python311\python.exe over to C:\python311\python3.exe, but that should have been done by the installer?

[pochmann]

Why are you typing python3 instead of python? You chose the option "Add python.exe to PATH", not "Add python3.exe to PATH", so why do you expect there to be a python3.exe?

[juj]

Why are you typing python3 instead of python

I am trying to build the Google v8 JS shell, which uses depot_tools(https://www.chromium.org/developers/how-tos/install-depot-tools/) package, which invokes python3 as part of its build script.

If that is the wrong thing to do and python3 should not be executed on Windows (which is odd given PEP 394 which suggests that on Unix-likes Python 3 may be present via invoking python3, not sure why it would be any different for Windows), I can raise this as a bug report against depot_tools, though it does not seem like this would be Google's fault.

You chose the option "Add python.exe to PATH", not "Add python3.exe to PATH"

There is no option "Add python3.exe to PATH" in the installer. Maybe such an option should then be added, if that is the problem?

why do you expect there to be a python3.exe?

Among other things because of that PEP 394, which states

"When invoked, python2 should run some version of the Python 2 interpreter, and python3 should run some version of the Python 3 interpreter."

[pochmann]

PEP 394's name is "The “python” Command on Unix-Like Systems", and Windows is no Unix-like system. It even has a section Exclusion of MS Windows which says "This PEP deliberately excludes any proposals relating to Microsoft Windows".

If Python doesn't promise the existence of python3, then its non-existence isn't a bug in Python but in the other software that assumes its existence.

The depot_tools setup tutorial mentions python.exe but not python3.exe, so looks like depot_tools even already knows the correct name...

[juj]

I am not following a setup tutorial, but I am running the automated depot_tools build script, which programmatically invokes python3 on Windows.

If Python doesn't promise the existence of python3, then its non-existence isn't a bug in Python but in the other software that assumes its existence.

What is the point of devising the whole python2, python3 scheme if one OS is deliberately excluded from it? Why deliberately break cross-platform compatibility? There are no downsides to having python3.exe also on Windows Python 3 installations.

[juj]

Raised a bug report against depot_tools in Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=1395090

[eryksun]

As a workaround, looks like one can copy C:\python311\python.exe over to C:\python311\python3.exe

If you create a symlink, then you won't have to manually replace "python3.exe" if you do an in-place update. For example:

>>> import os, sys
>>> dst = os.path.join(os.path.dirname(sys.executable), 'python3.exe')
>>> os.symlink('python.exe', dst)

[iritkatriel]

Is there anything left to do here?

[juj]

I agree with ecmziegler on depot_tools bug tracker, who commented

Though I think they make it unnecessarily hard on Windows for cross-platform applications. Just because
the spec does not require it does not mean it can't be done.

I still think Windows installations of Python 3 should provide python3.exe. The rationales above of why not do not seem particularly convincing.

[zooba]

Closing this as a dup of #99185