[New-bugs-announce] [issue43933] Regression in python3.10 with traceback frame having lineno of -1

[Anthony Sottile]

New submission from Anthony Sottile <asottile at umich.edu>:

This is breaking pytest for failed assertions: https://github.com/pytest-dev/pytest/pull/8227

It also breaks the traceback in the output below

Here's a minimal example:

```python
class Boom:
    def __enter__(self):
        return self
    def __exit__(self, *_):
        raise AssertionError('boom!')


def main() -> int:
    with Boom():
        raise AssertionError('hi')


if __name__ == '__main__':
    exit(main())
```

On python3.9 you get this:

```
Traceback (most recent call last):
  File "/home/asottile/workspace/cpython/t.py", line 10, in main
    raise AssertionError('hi')
AssertionError: hi

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/asottile/workspace/cpython/t.py", line 14, in <module>
    exit(main())
  File "/home/asottile/workspace/cpython/t.py", line 10, in main
    raise AssertionError('hi')
  File "/home/asottile/workspace/cpython/t.py", line 5, in __exit__
    raise AssertionError('boom!')
AssertionError: boom!
```

output in python3.10:

```
Traceback (most recent call last):
  File "/home/asottile/workspace/cpython/t.py", line 10, in main
    raise AssertionError('hi')
AssertionError: hi

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/asottile/workspace/cpython/t.py", line 14, in <module>
    exit(main())
  File "/home/asottile/workspace/cpython/t.py", line -1, in main
  File "/home/asottile/workspace/cpython/t.py", line 5, in __exit__
    raise AssertionError('boom!')
AssertionError: boom!
```

Notice the second to last frame is now missing and invalid (line -1)

I bisected this and found this is the culprit:


https://github.com/python/cpython/commit/3bd6035b6baf1a7d51b7cc2c6bb2c81886236b67
https://github.com/python/cpython/pull/24202

```
3bd6035b6baf1a7d51b7cc2c6bb2c81886236b67 is the first bad commit
commit 3bd6035b6baf1a7d51b7cc2c6bb2c81886236b67
Author: Mark Shannon <mark at hotpy.org>
Date:   Wed Jan 13 12:05:43 2021 +0000

    bpo-42908: Mark cleanup code at end of try-except and with artificial (#24202)
    
    * Mark bytecodes at end of try-except as artificial.
    
    * Make sure that the CFG is consistent throughout optimiization.
    
    * Extend line-number propagation logic so that implicit returns after 'try-except' or 'with' have the correct line numbers.
    
    * Update importlib

 Lib/test/test_dis.py          |    2 +-
 Lib/test/test_sys_settrace.py |   40 +
 Python/compile.c              |  135 +-
 Python/importlib.h            | 3153 ++++++++++++++---------------
 Python/importlib_external.h   | 4489 ++++++++++++++++++++---------------------
 Python/importlib_zipimport.h  | 1013 +++++-----
 6 files changed, 4473 insertions(+), 4359 deletions(-)
bisect run success
```

which appears to be due to bpo-42908

----------
messages: 391795
nosy: Anthony Sottile, Mark.Shannon, pablogsal
priority: normal
severity: normal
status: open
title: Regression in python3.10 with traceback frame having lineno of -1
versions: Python 3.10, Python 3.11

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43933>
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