gh-101865: Deprecate co_lnotab from code objects as per PEP 626

[sobolevn]

I still have to fix these lines:

cpython/Misc/gdbinit

Lines 60 to 61 in 6ef6915

	set $__sz = ((PyVarObject *)$__co->co_lnotab)->ob_size/2
	set $__p = (unsigned char *)((PyBytesObject *)$__co->co_lnotab)->ob_sval

But, since I have 0 experience with gdb it might take some time.

• Issue: co_lnotab must be removed in 3.12 according to PEP 626 #101865

[sobolevn]

I've pushed my naive attempt to fix gdb: since it only needs a current line f->f_lineno seems like a tool for the job. (again, this is my very first time working with gdb)

[sobolevn]

@markshannon friendly ping :)

[sobolevn]

Failures do not seem related 🤔

[arhadthedev]

test_implied_dirs_performance issue was fixed in gh-102225 so merging main should help.

[sobolevn]

@markshannon do you have time to re-review this, please? :)

[sobolevn]

@carljm maybe you can have a look? :)

[markshannon]

Looks good in general.
We aren't obliged to remove co_lnotab in 3.14, but we can. Perhaps change the "will"s to "may"s.

Not sure what to do about Misc/gdbinit though.

[markshannon]

Perhaps we should discuss the future of Misc/gdbinit in another issue, and not worry about it here.

[sobolevn]

@markshannon thanks a lot for your review and for all your hard work on CPython!

1. I've addressed all your comments
2. I've opened a new issue about Misc/gdbinit: What to do with Misc/gdbinit? #102809

[hugovk]

Shall we add a .. deprecated-removed: 3.12 3.14 in the main docs, somewhere near https://docs.python.org/3.12/reference/datamodel.html?highlight=co_lnotab ?

[sobolevn]

I think that we can add "is deprecated since 3.12 and may be removed in 3.14".
But this directive won't work, because it is a raw text:

1. https://github.com/python/cpython/blame/3adb23a17d25e36bd80874e860835182d851623f/Doc/reference/datamodel.rst#L965
2. https://github.com/python/cpython/blame/3adb23a17d25e36bd80874e860835182d851623f/Doc/reference/datamodel.rst#L992

[hugovk]

I think that we can add "is deprecated since 3.12 and may be removed in 3.14".

Sure, let's do something like that.

[sobolevn]

gdbinit was removed in #102854 🎉

[sobolevn]

@markshannon I've solved the merge conflicts. I hope that this is ready to be merged when you have the time :)