# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html # For details: https://github.com/PyCQA/pylint/blob/main/LICENSE # Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt """Looks for overlapping exceptions.""" from __future__ import annotations from typing import TYPE_CHECKING, Any import astroid from astroid import nodes, util from pylint import checkers from pylint.checkers import utils from pylint.checkers.exceptions import _annotated_unpack_infer if TYPE_CHECKING: from pylint.lint import PyLinter 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). """ name = "overlap-except" msgs = { "W0714": ( "Overlapping exceptions (%s)", "overlapping-except", "Used when exceptions in handler overlap or are identical", ) } options = () @utils.only_required_for_messages("overlapping-except") def visit_tryexcept(self, node: nodes.TryExcept) -> None: """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: list[tuple[Any, Any]] = [] for part, exc in excs: if isinstance(exc, util.UninferableBase): continue if isinstance(exc, astroid.Instance) and utils.inherit_from_std_ex(exc): 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=f"{prev_part.as_string()} and {part.as_string()} are the same", ) 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=f"{ancestor.as_string()} is an ancestor class of {descendant.as_string()}", ) handled_in_clause += [(part, exc)] def register(linter: PyLinter) -> None: linter.register_checker(OverlappingExceptionsChecker(linter))