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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 checkers, interfaces
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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