Accept macosx_10_9 platform for Big Sur

Environment

• pip version: 20.2.4
• Python version: 3.8.6
• OS: MacOS 11 (Big Sur)

Description

The update to Big Sur changed the major version of MacOS. AFAICS this is not really related to internals but more because of face lift and commercial concerns. But it’s forcing pip to build everything from sources (which is not only slow but tends to fail for complex packages like numpy).

I’m using the --platform flag as a workaround but it requires to also specify --target and --only-binary, which is not really convenient.

Expected behavior

Wheels for previous versions are used.

How to Reproduce

1. pip install numpy
2. Tries to build.
3. Fails to build

Instead:

1. pip install --platform macosx_10_9_x86_64 --only-binary=:all: --target=/tmp numpy
2. Downloads wheel
3. Works fine

Output

This is not really relevant, I’m not concerned with the reasons the build failed (related to blas and lapack) but because the build happens at all.

[ogrisel]

This has been fixed in https://github.com/pypa/packaging/pull/319 and related PRs in CPython so I guess the fix will be released soon-ish. It “just” needed someone with the time an knowledge to review the pull requests to add support for Big Sur to CPython related repos. Ironically the person who reviewed that last PR in this case works at Microsoft.

If Apple paid more full time employees to work as core developers on major open source projects such as CPython such fixes would be faster included when they release a new version of their OS.

Pending that, the easy workaround is just to wait for some time before upgrading to a new OS while open source maintainers do the work at their own pace instead.

[memeplex]

I’ve been using this horrible hack:

    version_str, _, cpu_arch = platform.mac_ver()  # type: ignore
    version_str = "10.15.1"

in site-packages/pip/_vendor/packaging/tags.py and after installing my environments everything seems to work fine.

The solution to this issue may be in changing pip or in building wheels for 11, this depends on the level of compatibility of MacOS 11 wrt 10.

This is OT, but do you know why there aren’t wheels for 11 yet and how long does the build usually take?