gh-123142: Fix too wide source locations in tracebacks of exceptions from broken iterables in comprehensions

[iritkatriel]

• Issue: Source locations too broad for list comprehension iterable expression #123142

[markshannon]

The code change looks good.
At least class Iter and maybe some more of the tests could be shared

[bedevere-app]

When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.

[iritkatriel]

I have made the requested changes; please review again.

[bedevere-app]

Thanks for making the requested changes!

@markshannon: please review the changes made to this pull request.

[markshannon]

Looks good.

The code in the three with self.subTest(func) blocks look the same/very similar. I think they could be factored out, but that might just end up obscuring the intent. It's up to you if you want to factor it further.

[miss-islington-app]

Thanks @iritkatriel for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13.
🐍🍒⛏🤖

[miss-islington-app]

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

cherry_picker ec89620e5e147ba028a46dd695ef073a72000b84 3.13

[miss-islington-app]

Sorry, @iritkatriel, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker ec89620e5e147ba028a46dd695ef073a72000b84 3.12

[bedevere-app]

GH-123209 is a backport of this pull request to the 3.13 branch.

[bedevere-app]

GH-123210 is a backport of this pull request to the 3.12 branch.

[15r10nk]

@iritkatriel might it be that this fix changed the source range for exceptions in __init__ and __next__ but not for exceptions in __iter__.

class Foo:
    def __iter__(self):
        assert False

a = [x for x in Foo()]

output (Python 3.13.0rc1+):

Traceback (most recent call last):
  File "/home/frank/projects/cpython/codi.py", line 5, in <module>
    a = [x for x in Foo()]
        ^^^^^^^^^^^^^^^^^^
  File "/home/frank/projects/cpython/codi.py", line 3, in __iter__
    assert False
           ^^^^^
AssertionError

This is the example from the issue and I'm a little confused as to whether it was just forgotten or if I'm missing something here.

[iritkatriel]

This is the example from the issue and I'm a little confused as to whether it was just forgotten or if I'm missing something here.

So it seems. The test doesn't check for this too. Thanks for reporting, I'll fix.