AF_DECnet is missing from socket.AddressFamily

[tungol]

Bug report

Bug description:

This code populates the AddressFamily enum:

IntEnum._convert_(
        'AddressFamily',
        __name__,
        lambda C: C.isupper() and C.startswith('AF_'))

But AF_DECnet isn't all uppercase so it's currently excluded. Do we need the isupper() test? I don't see anything that begins with AF_ in socket other than the existing members of AddressFamily and AF_DECnet.

CPython versions tested on:

3.13

Operating systems tested on:

macOS

Linked PRs

• gh-127544: Ensure that AF_DECnet is part of socket.AddressFamily, when available #127548

[rruuaanng]

That being said, AF_DECnet obsolete and exists only for compatibility with older VAX computers. It can be safely removed or ignore it.

ref:
https://en.wikipedia.org/wiki/VAX
https://en.wikipedia.org/wiki/DECnet

[tungol]

I don't think there's any reason to drop it as long as the OS support is there, and no reason not to fix the discrepancy once it's been noticed.

[oskar-skog]

DECnet code in the Linux kernel was marked as orphaned on February 18, 2010[4][5] and removed August 22, 2022.[6]

[rruuaanng]

cc @ZeroIntensity, Look this, for this request. WDYT?

[ZeroIntensity]

removed August 22, 2022

I am certain we support Linux versions older than 2022.

[tungol]

The same article also mentions a BSD implementation without saying anything about that one being removed.