Code objects with non-equal co_linetables compare equal

[15r10nk]

Bug report

def f(a, b):
    return dict((k.lower(), v) for k, v in a.items()) == dict(
        (k.lower(), v) for k, v in b.items()
    )

f({"a": 5}, {1: 1})

output:

Traceback (most recent call last):
  File "/home/frank/projects/executing/test8.py", line 8, in <module>
    f({"a": 5}, {1: 1})
  File "/home/frank/projects/executing/test8.py", line 2, in f
    return dict((k.lower(), v) for k, v in a.items()) == dict(
                                                         ^^^^^
  File "/home/frank/projects/executing/test8.py", line 2, in <genexpr>
    return dict((k.lower(), v) for k, v in a.items()) == dict(
                 ^^^^^^^
AttributeError: 'int' object has no attribute 'lower'

The error should be reported at line 3 and not at line 2, because the integer is passed to b

Your environment

• current cpython 3.11 branch (3a33e9b)
• and the Python 3.11.0b4

[alexmojaki]

Simpler reproduction:

[k.lower() for k in "a"], [k.lower() for k in [1]]

Traceback (most recent call last):
  File "...", line 1, in <module>
    [k.lower() for k in "a"], [k.lower() for k in [1]]
                              ^^^^^^^^^^^^^^^^^^^^^^^^
  File "...", line 1, in <listcomp>
    [k.lower() for k in "a"], [k.lower() for k in [1]]
     ^^^^^^^^^
AttributeError: 'int' object has no attribute 'lower'

[brandtbucher]

Ooh, nice find! The code objects are being "deduplicated" in the compiler, even though they have different column positions.

>>> def f():
...     (a for b in c), (a for b in d)
... 
>>> f.__code__.co_consts
(None, <code object <genexpr> at 0x7fa4fbf92640, file "<stdin>", line 2>)

We need to consider the entire positions table when comparing code objects for equality.

[brandtbucher]

@markshannon: we should add co_linetable to the code equality (and maybe hash?) functions.

Probably co_exceptiontable too, since I’m pretty sure it’s possible to have two code objects that differ only in exception table when compiling custom ASTs. We definitely don't want those to dedup.