Python 3.11 sysconfig.get_preferred_scheme("prefix") returns non prefix scheme

[robtaylor]

Output of brew config

HOMEBREW_VERSION: 4.1.17
ORIGIN: https://github.com/Homebrew/brew
HEAD: 35746e0a6ba6c3c5cfe56d99f79d9ec9f52ee15f
Last commit: 2 days ago
Core tap JSON: 24 Oct 16:39 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_MAKE_JOBS: 8
Homebrew Ruby: 2.6.10 => /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby
CPU: octa-core 64-bit arm_blizzard_avalanche
Clang: 14.0.3 build 1403
Git: 2.39.2 => /Library/Developer/CommandLineTools/usr/bin/git
Curl: 7.84.0 => /usr/bin/curl
macOS: 13.1-arm64
CLT: 14.3.1.0.1.1683849156
Xcode: 14.1
Rosetta 2: false

Output of brew doctor

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Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
  jsonschema

Warning: You have unlinked kegs in your Cellar.
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  python-certifi
  python-pyproject-hooks
  python-pytz
  python-packaging
  pygments
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  cffi
  meson
  python-build
  jsonschema
  keyring
  six
  virtualenv

Warning: Your Xcode (14.1) is outdated.
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Description of issue

In homebrew's python, sysconfig returns osx_framework_library when you ask for the preferred prefix scheme. However osx_framework_library isn't a valid prefix scheme as per the python docs (indeed, it doesn't exist there!).

Also looking at sysconfig._INSTALL_SCHEMES["osx_framework_library"], it doesn't include the {prefix} variable, so cannot be used as a prefix install scheme!

Is this by accident or design?

% python3
Python 3.11.6 (main, Oct  2 2023, 20:46:14) [Clang 14.0.3 (clang-1403.0.22.14.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sysconfig
>>> print(sysconfig.get_default_scheme())
osx_framework_library
>>> sysconfig._INSTALL_SCHEMES["osx_framework_library"]
{'stdlib': '{installed_base}/{platlibdir}/python{py_version_short}', 'platstdlib': '{platbase}/{platlibdir}/python{py_version_short}', 'purelib': '/opt/homebrew/lib/python{py_version_short}/site-packages', 'platlib': '/opt/homebrew/{platlibdir}/python{py_version_short}/site-packages', 'include': '{installed_base}/include/python{py_version_short}{abiflags}', 'platinclude': '{installed_platbase}/include/python{py_version_short}{abiflags}', 'scripts': '/opt/homebrew/bin', 'data': '/opt/homebrew'}

Python used:

roberttaylor@Roberts-MacBook-Pro coriolis % which python3
/opt/homebrew/bin/python3
roberttaylor@Roberts-MacBook-Pro coriolis % brew info python3
==> [email protected]: stable 3.11.6 (bottled)
Interpreted, interactive, object-oriented programming language
https://www.python.org/
/opt/homebrew/Cellar/[email protected]/3.11.6 (3,287 files, 61.9MB) *
  Poured from bottle using the formulae.brew.sh API on 2023-10-24 at 17:39:56
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/p/[email protected]
License: Python-2.0
==> Dependencies
Build: pkg-config ✔
Required: mpdecimal ✔, openssl@3 ✔, sqlite ✔, xz ✔
==> Caveats
Python has been installed as
  /opt/homebrew/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /opt/homebrew/opt/[email protected]/libexec/bin

You can install Python packages with
  pip3 install <package>
They will install into the site-package directory
  /opt/homebrew/lib/python3.11/site-packages

tkinter is no longer included with this formula, but it is available separately:
  brew install [email protected]

gdbm (`dbm.gnu`) is no longer included in this formula, but it is available separately:
  brew install [email protected]
`dbm.ndbm` changed database backends in Homebrew Python 3.11.
If you need to read a database from a previous Homebrew Python created via `dbm.ndbm`,
you'll need to read your database using the older version of Homebrew Python and convert to another format.
`dbm` still defaults to `dbm.gnu` when it is installed.

For more information about Homebrew and Python, see: https://docs.brew.sh/Homebrew-and-Python
==> Analytics
install: 286,321 (30 days), 794,344 (90 days), 1,805,399 (365 days)
install-on-request: 158,668 (30 days), 445,480 (90 days), 917,372 (365 days)
build-error: 319 (30 days)