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Diffstat (limited to 'venv/Lib/site-packages/pylint/checkers/exceptions.py')
| -rw-r--r-- | venv/Lib/site-packages/pylint/checkers/exceptions.py | 546 |
1 files changed, 546 insertions, 0 deletions
diff --git a/venv/Lib/site-packages/pylint/checkers/exceptions.py b/venv/Lib/site-packages/pylint/checkers/exceptions.py new file mode 100644 index 0000000..360e1d1 --- /dev/null +++ b/venv/Lib/site-packages/pylint/checkers/exceptions.py @@ -0,0 +1,546 @@ +# -*- coding: utf-8 -*- +# Copyright (c) 2006-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr> +# Copyright (c) 2011-2014 Google, Inc. +# Copyright (c) 2012 Tim Hatch <tim@timhatch.com> +# Copyright (c) 2013-2018 Claudiu Popa <pcmanticore@gmail.com> +# Copyright (c) 2014 Brett Cannon <brett@python.org> +# Copyright (c) 2014 Arun Persaud <arun@nubati.net> +# Copyright (c) 2015 Rene Zhang <rz99@cornell.edu> +# Copyright (c) 2015 Florian Bruhin <me@the-compiler.org> +# Copyright (c) 2015 Steven Myint <hg@stevenmyint.com> +# Copyright (c) 2015 Ionel Cristian Maries <contact@ionelmc.ro> +# Copyright (c) 2016 Erik <erik.eriksson@yahoo.com> +# Copyright (c) 2016 Jakub Wilk <jwilk@jwilk.net> +# Copyright (c) 2017 Łukasz Rogalski <rogalski.91@gmail.com> +# Copyright (c) 2017 Martin von Gagern <gagern@google.com> +# Copyright (c) 2018 Mike Frysinger <vapier@gmail.com> +# Copyright (c) 2018 ssolanki <sushobhitsolanki@gmail.com> +# Copyright (c) 2018 Alexander Todorov <atodorov@otb.bg> +# Copyright (c) 2018 Ville Skyttä <ville.skytta@upcloud.com> + +# 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 + +"""Checks for various exception related errors.""" +import builtins +import inspect +import typing + +import astroid +from astroid.node_classes import NodeNG + +from pylint import checkers, interfaces +from pylint.checkers import utils + + +def _builtin_exceptions(): + def predicate(obj): + return isinstance(obj, type) and issubclass(obj, BaseException) + + members = inspect.getmembers(builtins, predicate) + return {exc.__name__ for (_, exc) in members} + + +def _annotated_unpack_infer(stmt, context=None): + """ + Recursively generate nodes inferred by the given statement. + If the inferred value is a list or a tuple, recurse on the elements. + Returns an iterator which yields tuples in the format + ('original node', 'inferred node'). + """ + if isinstance(stmt, (astroid.List, astroid.Tuple)): + for elt in stmt.elts: + inferred = utils.safe_infer(elt) + if inferred and inferred is not astroid.Uninferable: + yield elt, inferred + return + for inferred in stmt.infer(context): + if inferred is astroid.Uninferable: + continue + yield stmt, inferred + + +def _is_raising(body: typing.List) -> bool: + """Return true if the given statement node raise an exception""" + for node in body: + if isinstance(node, astroid.Raise): + return True + return False + + +OVERGENERAL_EXCEPTIONS = ("BaseException", "Exception") +BUILTINS_NAME = builtins.__name__ + +MSGS = { + "E0701": ( + "Bad except clauses order (%s)", + "bad-except-order", + "Used when except clauses are not in the correct order (from the " + "more specific to the more generic). If you don't fix the order, " + "some exceptions may not be caught by the most specific handler.", + ), + "E0702": ( + "Raising %s while only classes or instances are allowed", + "raising-bad-type", + "Used when something which is neither a class, an instance or a " + "string is raised (i.e. a `TypeError` will be raised).", + ), + "E0703": ( + "Exception context set to something which is not an exception, nor None", + "bad-exception-context", + 'Used when using the syntax "raise ... from ...", ' + "where the exception context is not an exception, " + "nor None.", + ), + "E0704": ( + "The raise statement is not inside an except clause", + "misplaced-bare-raise", + "Used when a bare raise is not used inside an except clause. " + "This generates an error, since there are no active exceptions " + "to be reraised. An exception to this rule is represented by " + "a bare raise inside a finally clause, which might work, as long " + "as an exception is raised inside the try block, but it is " + "nevertheless a code smell that must not be relied upon.", + ), + "E0710": ( + "Raising a new style class which doesn't inherit from BaseException", + "raising-non-exception", + "Used when a new style class which doesn't inherit from " + "BaseException is raised.", + ), + "E0711": ( + "NotImplemented raised - should raise NotImplementedError", + "notimplemented-raised", + "Used when NotImplemented is raised instead of NotImplementedError", + ), + "E0712": ( + "Catching an exception which doesn't inherit from Exception: %s", + "catching-non-exception", + "Used when a class which doesn't inherit from " + "Exception is used as an exception in an except clause.", + ), + "W0702": ( + "No exception type(s) specified", + "bare-except", + "Used when an except clause doesn't specify exceptions type to catch.", + ), + "W0703": ( + "Catching too general exception %s", + "broad-except", + "Used when an except catches a too general exception, " + "possibly burying unrelated errors.", + ), + "W0705": ( + "Catching previously caught exception type %s", + "duplicate-except", + "Used when an except catches a type that was already caught by " + "a previous handler.", + ), + "W0706": ( + "The except handler raises immediately", + "try-except-raise", + "Used when an except handler uses raise as its first or only " + "operator. This is useless because it raises back the exception " + "immediately. Remove the raise operator or the entire " + "try-except-raise block!", + ), + "W0711": ( + 'Exception to catch is the result of a binary "%s" operation', + "binary-op-exception", + "Used when the exception to catch is of the form " + '"except A or B:". If intending to catch multiple, ' + 'rewrite as "except (A, B):"', + ), + "W0715": ( + "Exception arguments suggest string formatting might be intended", + "raising-format-tuple", + "Used when passing multiple arguments to an exception " + "constructor, the first of them a string literal containing what " + "appears to be placeholders intended for formatting", + ), + "W0716": ( + "Invalid exception operation. %s", + "wrong-exception-operation", + "Used when an operation is done against an exception, but the operation " + "is not valid for the exception in question. Usually emitted when having " + "binary operations between exceptions in except handlers.", + ), +} + + +class BaseVisitor: + """Base class for visitors defined in this module.""" + + def __init__(self, checker, node): + self._checker = checker + self._node = node + + def visit(self, node): + name = node.__class__.__name__.lower() + dispatch_meth = getattr(self, "visit_" + name, None) + if dispatch_meth: + dispatch_meth(node) + else: + self.visit_default(node) + + def visit_default(self, node): # pylint: disable=unused-argument + """Default implementation for all the nodes.""" + + +class ExceptionRaiseRefVisitor(BaseVisitor): + """Visit references (anything that is not an AST leaf).""" + + def visit_name(self, name): + if name.name == "NotImplemented": + self._checker.add_message("notimplemented-raised", node=self._node) + + def visit_call(self, call): + if isinstance(call.func, astroid.Name): + self.visit_name(call.func) + if ( + len(call.args) > 1 + and isinstance(call.args[0], astroid.Const) + and isinstance(call.args[0].value, str) + ): + msg = call.args[0].value + if "%" in msg or ("{" in msg and "}" in msg): + self._checker.add_message("raising-format-tuple", node=self._node) + + +class ExceptionRaiseLeafVisitor(BaseVisitor): + """Visitor for handling leaf kinds of a raise value.""" + + def visit_const(self, const): + if not isinstance(const.value, str): + # raising-string will be emitted from python3 porting checker. + self._checker.add_message( + "raising-bad-type", node=self._node, args=const.value.__class__.__name__ + ) + + def visit_instance(self, instance): + # pylint: disable=protected-access + cls = instance._proxied + self.visit_classdef(cls) + + # Exception instances have a particular class type + visit_exceptioninstance = visit_instance + + def visit_classdef(self, cls): + if not utils.inherit_from_std_ex(cls) and utils.has_known_bases(cls): + if cls.newstyle: + self._checker.add_message("raising-non-exception", node=self._node) + + def visit_tuple(self, _): + self._checker.add_message("raising-bad-type", node=self._node, args="tuple") + + def visit_default(self, node): + name = getattr(node, "name", node.__class__.__name__) + self._checker.add_message("raising-bad-type", node=self._node, args=name) + + +class ExceptionsChecker(checkers.BaseChecker): + """Exception related checks.""" + + __implements__ = interfaces.IAstroidChecker + + name = "exceptions" + msgs = MSGS + priority = -4 + options = ( + ( + "overgeneral-exceptions", + { + "default": OVERGENERAL_EXCEPTIONS, + "type": "csv", + "metavar": "<comma-separated class names>", + "help": "Exceptions that will emit a warning " + 'when being caught. Defaults to "%s".' + % (", ".join(OVERGENERAL_EXCEPTIONS),), + }, + ), + ) + + def open(self): + self._builtin_exceptions = _builtin_exceptions() + super(ExceptionsChecker, self).open() + + @utils.check_messages( + "misplaced-bare-raise", + "raising-bad-type", + "raising-non-exception", + "notimplemented-raised", + "bad-exception-context", + "raising-format-tuple", + ) + def visit_raise(self, node): + if node.exc is None: + self._check_misplaced_bare_raise(node) + return + + if node.cause: + self._check_bad_exception_context(node) + + expr = node.exc + ExceptionRaiseRefVisitor(self, node).visit(expr) + + try: + inferred_value = expr.inferred()[-1] + except astroid.InferenceError: + pass + else: + if inferred_value: + ExceptionRaiseLeafVisitor(self, node).visit(inferred_value) + + def _check_misplaced_bare_raise(self, node): + # Filter out if it's present in __exit__. + scope = node.scope() + if ( + isinstance(scope, astroid.FunctionDef) + and scope.is_method() + and scope.name == "__exit__" + ): + return + + current = node + # Stop when a new scope is generated or when the raise + # statement is found inside a TryFinally. + ignores = (astroid.ExceptHandler, astroid.FunctionDef) + while current and not isinstance(current.parent, ignores): + current = current.parent + + expected = (astroid.ExceptHandler,) + if not current or not isinstance(current.parent, expected): + self.add_message("misplaced-bare-raise", node=node) + + def _check_bad_exception_context(self, node): + """Verify that the exception context is properly set. + + An exception context can be only `None` or an exception. + """ + cause = utils.safe_infer(node.cause) + if cause in (astroid.Uninferable, None): + return + + if isinstance(cause, astroid.Const): + if cause.value is not None: + self.add_message("bad-exception-context", node=node) + elif not isinstance(cause, astroid.ClassDef) and not utils.inherit_from_std_ex( + cause + ): + self.add_message("bad-exception-context", node=node) + + def _check_catching_non_exception(self, handler, exc, part): + if isinstance(exc, astroid.Tuple): + # Check if it is a tuple of exceptions. + inferred = [utils.safe_infer(elt) for elt in exc.elts] + if any(node is astroid.Uninferable for node in inferred): + # Don't emit if we don't know every component. + return + if all( + node + and (utils.inherit_from_std_ex(node) or not utils.has_known_bases(node)) + for node in inferred + ): + return + + if not isinstance(exc, astroid.ClassDef): + # Don't emit the warning if the inferred stmt + # is None, but the exception handler is something else, + # maybe it was redefined. + if isinstance(exc, astroid.Const) and exc.value is None: + if ( + isinstance(handler.type, astroid.Const) + and handler.type.value is None + ) or handler.type.parent_of(exc): + # If the exception handler catches None or + # the exception component, which is None, is + # defined by the entire exception handler, then + # emit a warning. + self.add_message( + "catching-non-exception", + node=handler.type, + args=(part.as_string(),), + ) + else: + self.add_message( + "catching-non-exception", + node=handler.type, + args=(part.as_string(),), + ) + return + + if ( + not utils.inherit_from_std_ex(exc) + and exc.name not in self._builtin_exceptions + ): + if utils.has_known_bases(exc): + self.add_message( + "catching-non-exception", node=handler.type, args=(exc.name,) + ) + + def _check_try_except_raise(self, node): + def gather_exceptions_from_handler( + handler + ) -> typing.Optional[typing.List[NodeNG]]: + exceptions = [] # type: typing.List[NodeNG] + if handler.type: + exceptions_in_handler = utils.safe_infer(handler.type) + if isinstance(exceptions_in_handler, astroid.Tuple): + exceptions = list( + { + exception + for exception in exceptions_in_handler.elts + if isinstance(exception, astroid.Name) + } + ) + elif exceptions_in_handler: + exceptions = [exceptions_in_handler] + else: + # Break when we cannot infer anything reliably. + return None + return exceptions + + bare_raise = False + handler_having_bare_raise = None + excs_in_bare_handler = [] + for handler in node.handlers: + if bare_raise: + # check that subsequent handler is not parent of handler which had bare raise. + # since utils.safe_infer can fail for bare except, check it before. + # also break early if bare except is followed by bare except. + + excs_in_current_handler = gather_exceptions_from_handler(handler) + + if not excs_in_current_handler: + bare_raise = False + break + if excs_in_bare_handler is None: + # It can be `None` when the inference failed + break + + for exc_in_current_handler in excs_in_current_handler: + inferred_current = utils.safe_infer(exc_in_current_handler) + if any( + utils.is_subclass_of( + utils.safe_infer(exc_in_bare_handler), inferred_current + ) + for exc_in_bare_handler in excs_in_bare_handler + ): + bare_raise = False + break + + # `raise` as the first operator inside the except handler + if _is_raising([handler.body[0]]): + # flags when there is a bare raise + if handler.body[0].exc is None: + bare_raise = True + handler_having_bare_raise = handler + excs_in_bare_handler = gather_exceptions_from_handler(handler) + else: + if bare_raise: + self.add_message("try-except-raise", node=handler_having_bare_raise) + + @utils.check_messages("wrong-exception-operation") + def visit_binop(self, node): + if isinstance(node.parent, astroid.ExceptHandler): + # except (V | A) + suggestion = "Did you mean '(%s, %s)' instead?" % ( + node.left.as_string(), + node.right.as_string(), + ) + self.add_message("wrong-exception-operation", node=node, args=(suggestion,)) + + @utils.check_messages("wrong-exception-operation") + def visit_compare(self, node): + if isinstance(node.parent, astroid.ExceptHandler): + # except (V < A) + suggestion = "Did you mean '(%s, %s)' instead?" % ( + node.left.as_string(), + ", ".join(operand.as_string() for _, operand in node.ops), + ) + self.add_message("wrong-exception-operation", node=node, args=(suggestion,)) + + @utils.check_messages( + "bare-except", + "broad-except", + "try-except-raise", + "binary-op-exception", + "bad-except-order", + "catching-non-exception", + "duplicate-except", + ) + def visit_tryexcept(self, node): + """check for empty except""" + self._check_try_except_raise(node) + exceptions_classes = [] + nb_handlers = len(node.handlers) + for index, handler in enumerate(node.handlers): + if handler.type is None: + if not _is_raising(handler.body): + self.add_message("bare-except", node=handler) + + # check if an "except:" is followed by some other + # except + if index < (nb_handlers - 1): + msg = "empty except clause should always appear last" + self.add_message("bad-except-order", node=node, args=msg) + + elif isinstance(handler.type, astroid.BoolOp): + self.add_message( + "binary-op-exception", node=handler, args=handler.type.op + ) + else: + try: + excs = list(_annotated_unpack_infer(handler.type)) + except astroid.InferenceError: + continue + + 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 + + self._check_catching_non_exception(handler, exc, part) + + if not isinstance(exc, astroid.ClassDef): + continue + + exc_ancestors = [ + anc + for anc in exc.ancestors() + if isinstance(anc, astroid.ClassDef) + ] + + for previous_exc in exceptions_classes: + if previous_exc in exc_ancestors: + msg = "%s is an ancestor class of %s" % ( + previous_exc.name, + exc.name, + ) + self.add_message( + "bad-except-order", node=handler.type, args=msg + ) + if ( + exc.name in self.config.overgeneral_exceptions + and exc.root().name == utils.EXCEPTIONS_MODULE + and not _is_raising(handler.body) + ): + self.add_message( + "broad-except", args=exc.name, node=handler.type + ) + + if exc in exceptions_classes: + self.add_message( + "duplicate-except", args=exc.name, node=handler.type + ) + + exceptions_classes += [exc for _, exc in excs] + + +def register(linter): + """required method to auto register this checker""" + linter.register_checker(ExceptionsChecker(linter)) |