dis.cmp_op doc is inaccurate in Python 3.12.2 and 3.13.0a5

[Christopher-Chianelli]

Bug report

Bug description:

From https://docs.python.org/3.12/library/dis.html#opcode-COMPARE_OP,
dis.cmp_op should be able lookup the comparison operation string from the opcode's argument.
However, in Python 3.12.2 and 3.13.0a5, this fails with "IndexError: tuple index out of range"

import dis

def my_fun(a, b):
    return a <= b

for instruction in dis.get_instructions(my_fun):
    if instruction.opname == 'COMPARE_OP':
        print(dis.cmp_op[instruction.arg])

In Python 3.11.8, it prints "<=" as expected.

dis.dis output of my_fun in Python 3.12.2:

  1           0 RESUME                   0

  2           2 LOAD_FAST                0 (a)
              4 LOAD_FAST                1 (b)
              6 COMPARE_OP              26 (<=)
             10 RETURN_VALUE

dis.cmp_op in Python 3.12.2:

('<', '<=', '==', '!=', '>', '>=')

Workaround: use instruction.argrepr.

CPython versions tested on:

3.12, 3.13

Operating systems tested on:

Linux

Linked PRs

• gh-117270: Add missed change to COMPARE_OP from 3.12 to dis documentation #117272
• [3.12] gh-117270: Add missed change to COMPARE_OP from 3.12 to dis documentation (GH-117272) #117274

[gaogaotiantian]

You need to check the latest docs for the latest Python version. opname is changed in 3.13 so the lookup is different. You should use cmp_op[opname >> 5]

Oh, you meant 3.12 fails as well. Then that's probably a docs issue.

[Christopher-Chianelli]

Look like for 3.12, it is cmp_op[opname >> 4]

[gaogaotiantian]

Yes, the docs was changed when it was changed to [opname >> 5], but it was never updated when it was changed to [opname >> 4]

[gaogaotiantian]

This was changed in 6e4e14d but the docs is never updated. I can fix the 3.12 docs unless you want to do it @Christopher-Chianelli ?

[Christopher-Chianelli]

I can do it

[gaogaotiantian]

Sure, thanks for that!