architecture-specific binaries are preferred on macOS when universal2 should always be selected

Description

If pip sees both x86_64 and universal2 wheels on an x86_64 machine, it will prefer to install x86_64 wheels, creating a partially-broken virtual environment that cannot be used to create universal2 (i.e. “broadly usable”) redistributables.

Expected behavior

I would expect that pip would prefer to install universal2 artifacts when available, so that when building an app with e.g. py2app in a virtual environment created with pip, I’d be able to create a universal2 application even if I don’t have an Apple Silicon mac handy.

This is particularly an issue because package maintainers who want to be friendly to older versions of pip that don’t support universal2 properly are creating architecture-specific binaries, and the existence of those creates a worse and more error-prone experience for newer, more up-to-date pip users.

pip version

22.3

Python version

3.11.0

OS

macOS

How to Reproduce

arch -arch x86_64 ./asdf/bin/python3 -m pip install cryptography

Output

Downloading http://127.0.0.1:3141/root/pypi/%2Bf/3fc/26e22840b7732/cryptography-38.0.1-cp36-abi3-macosx_10_10_x86_64.whl (2.8 MB)

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[albertosottile]

This is actually exacerbated by the impossibility of manually installing universal2 wheels when platform-specific wheels are also available (see https://github.com/pypa/pip/issues/5453).

[pradyunsg]

x-ref https://github.com/pypa/packaging/issues/381