gh-92897: Ensure venv --copies respects source build property of the creating interpreter (GH-92899)

[jkloth]

There is a discrepancy between a symlink venv and a copied venv when determining whether the interpreter is considered to be from a source build. A symlink venv indicates True for sysconfig.is_python_build() whereas a copied venv returns False.

Since symlink venvs are the default for POSIX (where the majority of source builds would be used/tested), I have opted to use that behavior as correct. Windows users are far more likely to use the binary installer so odds of venvs being created from source builds are quite low. Likewise with venv --copies on POSIX.

These changes will allow for building extensions out of venvs created from source builds without any pre-configuration steps (see this section from pyperformance documentation).

Adding @zooba for Windows and @vsajip for venv

• Issue: Ensure venv works with source builds when using --copies #92897

[zooba]

Don't touch distutils - it's going to be deleted in this release anyway, and there are no maintenance releases where it is undeprecated.

If we're using it within the stdlib, update the references elsewhere. If setuptools is impacted, they need the patch.

I haven't looked any deeper than that - it's late. I'll try and take a look later this week

[jkloth]

The changes to distutils are only to keep it from raising exceptions. Since it is being removed, I saw no need to keep private functions around just for use within distutils which would prevent a more straight forward implementation. Hence the modifications to distutils.

The changes to stdlib sysconfig have no impact on setuptools distutils.sysconfig so nothing to do there.

[vstinner]

The changes to distutils are only to keep it from raising exceptions.

In practice, setuptools now injects its own distutils flavor, so I am not sure that it's worth it to modify it here. At least, you should get your change merged first in https://github.com/pypa/distutils/

[jkloth]

distutils.sysconfig and distutils.test.test_sysconfig in the stdlib have diveraged from those in setuptools (PR #23142). Therefore the changes included here have ZERO correspondance to those in setuptools. distutils.sysconfig in setuptools does not rely on any private functions from sysconfig so there is no change to merge.

[jkloth]

To make it absolutely clear, the changes here to distutils modules are solely to prevent an ImportError from occurring wherever distutils modules are still used in the stdlib. The changes are intended to keep it "working" until it can be fully removed at a later date.

[zooba]

LGTM, and appears to handle the case on Windows where a venv is created from a source build. I can only assume the behaviour is correct on other platforms?

[jkloth]

As far as other platforms go, it is tested on Ubuntu (WSL).

[miss-islington]

Thanks @jkloth for the PR, and @vsajip for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖

[miss-islington]

Thanks @jkloth for the PR, and @vsajip for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

[miss-islington]

Sorry, @jkloth and @vsajip, I could not cleanly backport this to 3.10 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 067597522a9002f3b8aff7f46033f10acb2381e4 3.10

[miss-islington]

Sorry @jkloth and @vsajip, I had trouble checking out the 3.11 backport branch.
Please backport using cherry_picker on command line.
cherry_picker 067597522a9002f3b8aff7f46033f10acb2381e4 3.11

[bedevere-bot]

GH-94567 is a backport of this pull request to the 3.11 branch.

[bedevere-bot]

GH-94572 is a backport of this pull request to the 3.10 branch.