False positive redefined-outer-name for variables bound to the exception in except clauses

[MikhailRyazanov]

Bug description

# pylint: disable=missing-module-docstring, missing-function-docstring
def f():
    try:
        raise ValueError('inner')
    except ValueError as e:
        print(e)

try:
    raise ValueError('outer')
except ValueError as e:
    print(e)

# print(e)  # NameError: name 'e' is not defined

Configuration

No response

Command used

pylint a.py

Pylint output

************* Module a
a.py:5:4: W0621: Redefining name 'e' from outer scope (line 10) (redefined-outer-name)

Expected behavior

Pylint must not complain about reusing variables bound to the exception in except clauses because they are in fact not defined outside the corresponding except clause (as can be seen by uncommenting the last line in the example).

Pylint version

pylint 3.2.2
astroid 3.2.2
Python 3.12.3 (main, Apr 10 2024, 05:33:47) [GCC 13.2.0]

OS / Environment

No response

Additional dependencies

No response

[MikhailRyazanov]

@mbyrnepr2, this attempt:

pylint/pylint/checkers/variables.py

Lines 1523 to 1524 in 805663a

	if line > stmt.lineno:
	continue

doesn't make much sense because the same behavior is observed when the order is reversed:

# pylint: disable=missing-module-docstring, missing-function-docstring
try:
    raise ValueError('outer')
except ValueError as e:
    print(e)

def f():
    try:
        raise ValueError('inner')
    except ValueError as e:
        print(e)

a.py:10:4: W0621: Redefining name 'e' from outer scope (line 4) (redefined-outer-name)

Pylint should really understand that the variable from except ... as ...: doesn't exist outside the except block.
If it would help, this is what Python documentation says:

When an exception has been assigned using as target, it is cleared at the end of the except clause. This is as if

except E as N:
   foo

was translated to

except E as N:
   try:
       foo
   finally:
       del N

As a side note, Pylint apparently doesn't understand explicit del either (I'm not saying that using it to redefine variables can be considered “good”, but if Pylint had working logic for del, it could be used for correcting this except problem).

[mbyrnepr2]

Thank you @MikhailRyazanov. That indeed makes plenty of sense!
I've taken an alternative approach and perhaps this can be a workable solution for this case.
FYI since you mentioned del there is some reading you can check out here on that.