gh-41779: Allow defining any __slots__ for a class derived from tuple

[serhiy-storchaka]

• Issue: __slots__ for subclasses of variable length types #41779

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📚 Documentation preview 📚: https://cpython-previews--141763.org.readthedocs.build/

[encukou]

This looks OK but I don't know enough about the specializer to review properly.

[encukou]

@markshannon Is this compatible with the laout you had in mind for the “Grand Unified Python Object Layout”?

[serhiy-storchaka]

Let's merge this, and fix possible issues if they occur later.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 macOS 3.x (tier-2) has failed when building commit 4d21297.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/725/builds/12464) and take a look at the build logs.
4. Check if the failure is related to this commit (4d21297) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/725/builds/12464

Failed tests:

• test_urllib2net

Summary of the results of the build (if available):

==

Click to see traceback logs

remote: Enumerating objects: 24, done.        
remote: Counting objects:   4% (1/23)        
remote: Counting objects:   8% (2/23)        
remote: Counting objects:  13% (3/23)        
remote: Counting objects:  17% (4/23)        
remote: Counting objects:  21% (5/23)        
remote: Counting objects:  26% (6/23)        
remote: Counting objects:  30% (7/23)        
remote: Counting objects:  34% (8/23)        
remote: Counting objects:  39% (9/23)        
remote: Counting objects:  43% (10/23)        
remote: Counting objects:  47% (11/23)        
remote: Counting objects:  52% (12/23)        
remote: Counting objects:  56% (13/23)        
remote: Counting objects:  60% (14/23)        
remote: Counting objects:  65% (15/23)        
remote: Counting objects:  69% (16/23)        
remote: Counting objects:  73% (17/23)        
remote: Counting objects:  78% (18/23)        
remote: Counting objects:  82% (19/23)        
remote: Counting objects:  86% (20/23)        
remote: Counting objects:  91% (21/23)        
remote: Counting objects:  95% (22/23)        
remote: Counting objects: 100% (23/23)        
remote: Counting objects: 100% (23/23), done.        
remote: Compressing objects:   5% (1/20)        
remote: Compressing objects:  10% (2/20)        
remote: Compressing objects:  15% (3/20)        
remote: Compressing objects:  20% (4/20)        
remote: Compressing objects:  25% (5/20)        
remote: Compressing objects:  30% (6/20)        
remote: Compressing objects:  35% (7/20)        
remote: Compressing objects:  40% (8/20)        
remote: Compressing objects:  45% (9/20)        
remote: Compressing objects:  50% (10/20)        
remote: Compressing objects:  55% (11/20)        
remote: Compressing objects:  60% (12/20)        
remote: Compressing objects:  65% (13/20)        
remote: Compressing objects:  70% (14/20)        
remote: Compressing objects:  75% (15/20)        
remote: Compressing objects:  80% (16/20)        
remote: Compressing objects:  85% (17/20)        
remote: Compressing objects:  90% (18/20)        
remote: Compressing objects:  95% (19/20)        
remote: Compressing objects: 100% (20/20)        
remote: Compressing objects: 100% (20/20), done.        
remote: Total 24 (delta 3), reused 3 (delta 3), pack-reused 1 (from 1)        
From https://github.com/python/cpython
 * branch                    main       -> FETCH_HEAD
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HEAD is now at 4d21297d288 gh-41779: Allow defining any __slots__ for a class derived from tuple (GH-141763)
Switched to and reset branch 'main'

make: *** [buildbottest] Error 2