code.co_positions behaviour does not match documentation

The documentation of co_positions() says:

The iterator returns tuples containing the (start_line, end_line, start_column, end_column). The i-th tuple corresponds to the position of the source code that compiled to the i-th instruction.

I think this is incorrect, because the iterator returns tuples for cache entries as well:

>>> def f():
...   a.b = 1
... 
>>> import dis
>>> dis.dis(f)
  1           0 RESUME                   0

  2           2 LOAD_CONST               1 (1)
              4 LOAD_GLOBAL              0 (a)
             16 STORE_ATTR               1 (b)
             26 LOAD_CONST               0 (None)
             28 RETURN_VALUE
>>> len(list(f.__code__.co_positions()))
15
>>> from pprint import pprint as pp
>>> pp(list(f.__code__.co_positions()))
[(1, 1, 0, 0),
 (2, 2, 8, 9),
 (2, 2, 2, 3),
 (2, 2, 2, 3),
 (2, 2, 2, 3),
 (2, 2, 2, 3),
 (2, 2, 2, 3),
 (2, 2, 2, 3),
 (2, 2, 2, 5),
 (2, 2, 2, 5),
 (2, 2, 2, 5),
 (2, 2, 2, 5),
 (2, 2, 2, 5),
 (2, 2, 2, 5),
 (2, 2, 2, 5)]
>>>

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@markshannon

CC @markshannon @brandtbucher .

I think this is probably just a place where the docs could be improved.

Are you suggesting replacing "instruction" with "code unit"? Or adding a note that inline CACHE "instructions" are included? I'd be fine with either.

@markshannon

We discussed this at the meeting and I think the view was that the implementation needs to change. @markshannon ?

I don't think we can change the current behavior of emitting one tuple per code unit . The docs should reflect that behaviour.

I think it is co_lines() that we should modify. We can merge successive tuples with the same line number, now that #99556 is merged.

GH-100117: Make `co_lines` more efficient (GH-100447)

This shouldn't have been closed, the doc is still incorrect.

pythongh-100117: Fix inaccuracy in documentation of the CodeObject's …

gh-100117: Fix inaccuracy in documentation of the CodeObject's co_pos…

pythongh-100117: Fix inaccuracy in documentation of the CodeObject's …

[3.12] gh-100117: Fix inaccuracy in documentation of the CodeObject's…

[3.13] gh-100117: Fix inaccuracy in documentation of the CodeObject's…

pythongh-100117: Fix inaccuracy in documentation of the CodeObject's …

[3.11] gh-100117: Fix inaccuracy in documentation of the CodeObject's…

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code.co_positions behaviour does not match documentation #100117

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code.co_positions behaviour does not match documentation #100117

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iritkatriel commented on Dec 8, 2022

brandtbucher commented on Dec 21, 2022

iritkatriel commented on Dec 22, 2022

markshannon commented on Dec 22, 2022

iritkatriel commented on Dec 11, 2023

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