gh-133157: remove usage of _Py_NO_SANITIZE_UNDEFINED in Parser/pegen.c

[picnixz]

We remove undefined behaviors by adding more "overloads" functions. I've added some small checks to detect possible future undefined behaviors.

• Issue: UBsan: Remove _Py_NO_SANITIZE_UNDEFINED #133157

[picnixz]

@pablogsal friendly ping

[pablogsal]

LGTM. Great work on factoring this into a macro and the check in the generator 👌

[miss-islington-app]

Thanks @pablogsal for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

[miss-islington-app]

Sorry, @pablogsal, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 754e7c9b5187fcad22acf7555479603f173a4a09 3.13

[bedevere-app]

3.14 branch.

[pablogsal]

Can you do the backport to 3.13?

[picnixz]

I'll do the backport tomorrow! (I'm going to sleep in a few minutes :'))

[bedevere-app]

3.13 branch.

[bedevere-app]

3.13 branch.

[bedevere-bot]

⚠️⚠️ Buildbot failure ⚠️⚠️

Hi! The buildbot AMD64 Debian root 3.13 (tier-1) has failed when building commit dd7ffdb.

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/1441/builds/1259) and take a look at the build logs.
4. Check if the failure is related to this commit (dd7ffdb) 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/1441/builds/1259

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

Click to see traceback logs

remote: Enumerating objects: 10, done.        
remote: Counting objects:  10% (1/10)        
remote: Counting objects:  20% (2/10)        
remote: Counting objects:  30% (3/10)        
remote: Counting objects:  40% (4/10)        
remote: Counting objects:  50% (5/10)        
remote: Counting objects:  60% (6/10)        
remote: Counting objects:  70% (7/10)        
remote: Counting objects:  80% (8/10)        
remote: Counting objects:  90% (9/10)        
remote: Counting objects: 100% (10/10)        
remote: Counting objects: 100% (10/10), done.        
remote: Total 10 (delta 9), reused 9 (delta 9), pack-reused 0 (from 0)        
From https://github.com/python/cpython
 * branch                    3.13       -> FETCH_HEAD
Note: switching to 'dd7ffdbbff35d9a86906c71ee2c15a1cee02701d'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at dd7ffdbbff3 [3.13] gh-133157: fix UBSan failures in `Parser/pegen.c` (GH-134048) (#135334)
Switched to and reset branch '3.13'

configure: WARNING: no system libmpdecimal found; falling back to bundled libmpdecimal (deprecated and scheduled for removal in Python 3.15)
configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly.

make: *** wait: No child processes.  Stop.
make: *** Waiting for unfinished jobs....
make: *** wait: No child processes.  Stop.

Cannot open file '/root/buildarea/3.13.angelico-debian-amd64/build/test-results.xml' for upload