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# -*- coding: utf-8 -*-
# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/PyCQA/pylint/blob/master/COPYING
"""Looks for overlapping exceptions."""
import astroid
from pylint import interfaces
from pylint import checkers
from pylint.checkers import utils
from pylint.checkers.exceptions import _annotated_unpack_infer
class OverlappingExceptionsChecker(checkers.BaseChecker):
"""Checks for two or more exceptions in the same exception handler
clause that are identical or parts of the same inheritance hierarchy
(i.e. overlapping)."""
__implements__ = interfaces.IAstroidChecker
name = 'overlap-except'
msgs = {'W0714': ('Overlapping exceptions (%s)',
'overlapping-except',
'Used when exceptions in handler overlap or are identical')}
priority = -2
options = ()
@utils.check_messages('overlapping-except')
def visit_tryexcept(self, node):
"""check for empty except"""
for handler in node.handlers:
if handler.type is None:
continue
if isinstance(handler.type, astroid.BoolOp):
continue
try:
excs = list(_annotated_unpack_infer(handler.type))
except astroid.InferenceError:
continue
handled_in_clause = []
for part, exc in excs:
if exc is astroid.Uninferable:
continue
if (isinstance(exc, astroid.Instance) and
utils.inherit_from_std_ex(exc)):
# pylint: disable=protected-access
exc = exc._proxied
if not isinstance(exc, astroid.ClassDef):
continue
exc_ancestors = [anc for anc in exc.ancestors()
if isinstance(anc, astroid.ClassDef)]
for prev_part, prev_exc in handled_in_clause:
prev_exc_ancestors = [anc for anc in prev_exc.ancestors()
if isinstance(anc, astroid.ClassDef)]
if exc == prev_exc:
self.add_message('overlapping-except',
node=handler.type,
args='%s and %s are the same' %
(prev_part.as_string(),
part.as_string()))
elif (prev_exc in exc_ancestors or
exc in prev_exc_ancestors):
ancestor = part if exc in prev_exc_ancestors else prev_part
descendant = part if prev_exc in exc_ancestors else prev_part
self.add_message('overlapping-except',
node=handler.type,
args='%s is an ancestor class of %s' %
(ancestor.as_string(), descendant.as_string()))
handled_in_clause += [(part, exc)]
def register(linter):
"""Required method to auto register this checker."""
linter.register_checker(OverlappingExceptionsChecker(linter))
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