v2.15.5

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What's new in Pylint 2.15.5?

Release date: 2022-10-21

False Positives Fixed

• Fix a false positive for simplify-boolean-expression when multiple values are inferred for a constant.

  Closes #​7626

Other Bug Fixes

• Remove __index__ dunder method call from unnecessary-dunder-call check.

  Closes #​6795

• Fixed a multi-processing crash that prevents using any more than 1 thread on MacOS.

  The returned module objects and errors that were cached by the linter plugin loader cannot be reliably pickled. This means that dill would throw an error when attempting to serialise the linter object for multi-processing use.

  Closes #​7635.

Other Changes

• Add a keyword-only compare_constants argument to safe_infer.

  Refs #​7626

• Sort --generated-rcfile output.

  Refs #​7655

v2.15.4

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False Positives Fixed

• Fix the message for unnecessary-dunder-call for __aiter__ and __aneext__. Also only emit the warning when py-version >= 3.10.

  Closes #​7529

Other Bug Fixes

• Fix bug in detecting unused-variable when iterating on variable.

  Closes #​3044

• Fixed handling of -- as separator between positional arguments and flags. This was not actually fixed in 2.14.5.

  Closes #​7003, Refs #​7096

• Report no-self-argument rather than no-method-argument for methods with variadic arguments.

  Closes #​7507

• Fixed an issue where syntax-error couldn't be raised on files with invalid encodings.

  Closes #​7522

• Fix false positive for redefined-outer-name when aliasing typing e.g. as t and guarding imports under t.TYPE_CHECKING.

  Closes #​7524

• Fixed a crash of the modified_iterating checker when iterating on a set defined as a class attribute.

  Closes #​7528

• Fix bug in scanning of names inside arguments to typing.Literal. See https://peps.python.org/pep-0586/#literals-enums-and-forward-references for details.

  Refs #​3299

Other Changes

• Add method name to the error messages of no-method-argument and no-self-argument.

  Closes #​7507

v2.15.3

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• Fixed a crash in the unhashable-member checker when using a lambda as a dict key.

  Closes #​7453

• Fix a crash in the modified-iterating-dict checker involving instance attributes.

  Closes #​7461

• invalid-class-object does not crash anymore when __class__ is assigned alongside another variable.

  Closes #​7467

• Fix false positive for global-variable-not-assigned when a global variable is re-assigned via an ImportFrom node.

  Closes #​4809

• Fix false positive for undefined-loop-variable in for-else loops that use a function having a return type annotation of NoReturn or Never.

  Closes #​7311

• --help-msg now accepts a comma-separated list of message IDs again.

  Closes #​7471

v2.15.2

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• Fixed a case where custom plugins specified by command line could silently fail.

  Specifically, if a plugin relies on the init-hook option changing sys.path before it can be imported, this will now emit a bad-plugin-value message. Before this change, it would silently fail to register the plugin for use, but would load any configuration, which could have unintended effects.

  Fixes part of #​7264.

• Fix used-before-assignment for functions/classes defined in type checking guard.

  Closes #​7368

• Update modified_iterating checker to fix a crash with for loops on empty list.

  Closes #​7380

• The docparams extension now considers typing in Numpy style docstrings as "documentation" for the missing-param-doc message.

  Refs #​7398

• Fix false positive for unused-variable and unused-import when a name is only used in a string literal type annotation.

  Closes #​3299

• Fix false positive for too-many-function-args when a function call is assigned to a class attribute inside the class where the function is defined.

  Closes #​6592

• Fix used-before-assignment for functions/classes defined in type checking guard.

  Closes #​7368

• Fix ignored files being linted when passed on stdin.

  Closes #​4354

• missing-return-doc, missing-raises-doc and missing-yields-doc now respect the no-docstring-rgx option.

  Closes #​4743

• Don't crash on OSError in config file discovery.

  Closes #​7169

• disable-next is now correctly scoped to only the succeeding line.

  Closes #​7401

• Update modified_iterating checker to fix a crash with for loops on empty list.

  Closes #​7380

v2.15.0

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In pylint 2.15.0, we added a new check missing-timeout to warn of default timeout values that could cause a program to be hanging indefinitely.

We improved pylint's handling of namespace packages. More packages should be linted without resorting to using the --recursive=y option.

We still welcome any community effort to help review, integrate, and add good/bad examples to the doc for https://github.com/PyCQA/pylint/issues/5953. This should be doable without any pylint or astroid knowledge, so this is the perfect entrypoint if you want to contribute to pylint or open source without any experience with our code!

Internally, we changed the way we generate the release notes, thanks to DudeNr33. There will be no more conflict resolution to do in the changelog, and every contributor rejoice.

Marc Byrne became a maintainer, welcome to the team !

New Checks

• Added new checker missing-timeout to warn of default timeout values that could cause a program to be hanging indefinitely.

  Refs #​6780

False Positives Fixed

• Don't report super-init-not-called for abstract __init__ methods.

  Closes #​3975

• Don't report unsupported-binary-operation on Python <= 3.9 when using the | operator with types, if one has a metaclass that overloads __or__ or __ror__ as appropriate.

  Closes #​4951

• Don't report no-value-for-parameter for dataclasses fields annotated with KW_ONLY.

  Closes #​5767

• Fixed inference of Enums when they are imported under an alias.

  Closes #​5776

• Prevent false positives when accessing PurePath.parents by index (not slice) on Python 3.10+.

  Closes #​5832

• unnecessary-list-index-lookup is now more conservative to avoid potential false positives.

  Closes #​6896

• Fix double emitting trailing-whitespace for multi-line docstrings.

  Closes #​6936

• import-error now correctly checks for contextlib.suppress guards on import statements.

  Closes #​7270

• Fix false positive for no-self-argument/no-method-argument when a staticmethod is applied to a function but uses a different name.

  Closes #​7300

• Fix undefined-loop-variable with break and continue statements in else blocks.

  Refs #​7311

False Negatives Fixed

• Emit used-before-assignment when relying on a name that is reimported later in a function.

  Closes #​4624

• Emit used-before-assignment for self-referencing named expressions (:=) lacking prior assignments.

  Closes #​5653

• Emit used-before-assignment for self-referencing assignments under if conditions.

  Closes #​6643

• Emit modified-iterating-list and analogous messages for dicts and sets when iterating literals, or when using the del keyword.

  Closes #​6648

• Emit used-before-assignment when calling nested functions before assignment.

  Closes #​6812

• Emit nonlocal-without-binding when a nonlocal name has been assigned at a later point in the same scope.

  Closes #​6883

• Emit using-constant-test when testing the truth value of a variable or call result holding a generator.

  Closes #​6909

• Rename unhashable-dict-key to unhashable-member and emit when creating sets and dicts, not just when accessing dicts.

  Closes #​7034, Closes #​7055

Other Bug Fixes

• Fix a failure to lint packages with __init__.py contained in directories lacking __init__.py.

  Closes #​1667

• Fixed a syntax-error crash that was not handled properly when the declared encoding of a file was utf-9.

  Closes #​3860

• Fix a crash in the not-callable check when there is ambiguity whether an instance is being incorrectly provided to __new__().

  Closes #​7109

• Fix crash when regex option raises a re.error exception.

  Closes #​7202

• Fix undefined-loop-variable from walrus in comprehension test.

  Closes #​7222

• Check for <cwd> before removing first item from sys.path in modify_sys_path.

  Closes #​7231

• Fix sys.path pollution in parallel mode.

  Closes #​7246

• Prevent useless-parent-delegation for delegating to a builtin written in C (e.g. Exception.__init__) with non-self arguments.

  Closes #​7319

Other Changes

• bad-exception-context has been renamed to bad-exception-cause as it is about the cause and not the context.

  Closes #​3694

• The message for literal-comparison is now more explicit about the problem and the solution.

  Closes #​5237

• useless-super-delegation has been renamed to useless-parent-delegation in order to be more generic.

  Closes #​6953

• Pylint now uses towncrier for changelog generation.

  Refs #​6974

• Update astroid to 2.12.

  Refs #​7153

• Fix crash when a type-annotated __slots__ with no value is declared.

  Closes #​7280

Internal Changes

• Fixed an issue where it was impossible to update functional tests output when the existing output was impossible to parse. Instead of raising an error we raise a warning message and let the functional test fail with a default value.

  Refs #​6891

• pylint.testutils.primer is now a private API.

  Refs #​6905

• We changed the way we handle the changelog internally by using towncrier. If you're a contributor you won't have to fix merge conflicts in the changelog anymore.

  Closes #​6974

• Pylint is now using Scorecards to implement security recommendations from the OpenSSF <https://openssf.org/>_. This is done in order to secure our supply chains using a combination of automated tooling and best practices, most of which were already implemented before.

  Refs #​7267

v2.14.5

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• Fixed a crash in the undefined-loop-variable check when enumerate() is used in a ternary expression.

  Closes #​7131

• Fixed handling of -- as separator between positional arguments and flags.

  Closes #​7003

• Fixed the disabling of fixme and its interaction with useless-suppression.

• Allow lists of default values in parameter documentation for Numpy style.

  Closes #​4035

v2.14.4

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• The differing-param-doc check was triggered by positional only arguments.

  Closes #​6950

• Fixed an issue where scanning . directory recursively with --ignore-path=^path/to/dir is not ignoring the path/to/dir directory.

  Closes #​6964

• Fixed regression that didn't allow quoted init-hooks in option files.

  Closes #​7006

• Fixed a false positive for modified-iterating-dict when updating an existing key.

  Closes #​6179

• Fixed an issue where many-core Windows machines (>~60 logical processors) would hang when using the default jobs count.

  Closes #​6965

• Fixed an issue with the recognition of setup.cfg files. Only .cfg files that are exactly named setup.cfg require section names that start with pylint..

  Closes #​3630

• Don't report import-private-name for relative imports.

  Closes #​7078

v2.14.3

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• Fixed two false positives for bad-super-call for calls that refer to a non-direct parent.

  Closes #​4922, Closes #​2903

• Fixed a false positive for useless-super-delegation for subclasses that specify the number of of parameters against a parent that uses a variadic argument.

  Closes #​2270

• Allow suppressing undefined-loop-variable and undefined-variable without raising useless-suppression.

• Fixed false positive for undefined-variable for __class__ in inner methods.

  Closes #​4032

v2.14.2

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• Fixed a false positive for unused-variable when a function returns an argparse.Namespace object.

  Closes #​6895

• Avoided raising an identical undefined-loop-variable message twice on the same line.

• Don't crash if lint.run._query_cpu() is run within a Kubernetes Pod, that has only a fraction of a cpu core assigned. Just go with one process then.

  Closes #​6902

• Fixed a false positive in consider-using-f-string if the left side of a % is not a string.

  Closes #​6689

• Fixed a false positive in unnecessary-list-index-lookup and unnecessary-dict-index-lookup when the subscript is updated in the body of a nested loop.

  Closes #​6818

• Fixed an issue with multi-line init-hook options which did not record the line endings.

  Closes #​6888

• Fixed a false positive for used-before-assignment when a try block returns but an except handler defines a name via type annotation.

• --errors-only no longer enables previously disabled messages. It was acting as "emit all and only error messages" without being clearly documented that way.

  Closes #​6811

v2.14.1

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• Avoid reporting unnecessary-dict-index-lookup or unnecessary-list-index-lookup when the index lookup is part of a destructuring assignment.

  Closes #​6788

• Fixed parsing of unrelated options in tox.ini.

  Closes #​6800

• Fixed a crash when linting __new__() methods that return a call expression.

  Closes #​6805

• Don't crash if we can't find the user's home directory.

  Closes #​6802

• Fixed false positives for unused-import when aliasing typing e.g. as t and guarding imports under t.TYPE_CHECKING.

  Closes #​3846

• Fixed a false positive regression in 2.13 for used-before-assignment where it is safe to rely on a name defined only in an except block because the else block returned.

  Closes #​6790

• Fixed the use of abbreviations for some special options on the command line.

  Closes #​6810

• Fix a crash in the optional pylint.extensions.private_import extension.

  Closes #​6624

• bad-option-value (E0012) is now a warning unknown-option-value (W0012). Deleted messages that do not exist anymore in pylint now raise useless-option-value (R0022) instead of bad-option-value. This allows to distinguish between genuine typos and configuration that could be cleaned up. Existing message disables for bad-option-value will still work on both new messages.

  Refs #​6794

v2.14.0

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Summary -- Release highlights

With 2.14 pylint only supports Python version 3.7.2 and above.

We introduced several new checks among which duplicate-value for sets, comparison-of-constants, and checks related to lambdas. We removed no-init and made no-self-use optional as they were too opinionated. We also added an option to generate a toml configuration: --generate-toml-config.

We migrated to argparse from optparse and refactored the configuration handling thanks to Daniël van Noord. On the user side it should change the output of the --help command, and some inconsistencies and bugs should disappear. The behavior between options set in a config file versus on the command line will be more consistent. For us, it will permit to maintain this part of the code easily in the future and anticipate optparse's removal in Python 3.12.

As a result of the refactor there are a lot of internal deprecations. If you're a library maintainer that depends on pylint, please verify that you're ready for pylint 3.0 by activating deprecation warnings.

We continued the integration of pylint-error and are now at 33%!. We still welcome any community effort to help review, integrate, and add good/bad examples in #​5953. This should be doable without any pylint or astroid knowledge, so this is the perfect entrypoint if you want to contribute to pylint or open source without any experience with our code!

New checkers

• Added new checker comparison-of-constants.

  Closes #​6076

• Added new checker typevar-name-mismatch: TypeVar must be assigned to a variable with the same name as its name argument.

  Closes #​5224

• invalid-enum-extension: Used when a class tries to extend an inherited Enum class.

  Closes #​5501

• Added new checker typevar-double-variance: The "covariant" and "contravariant" keyword arguments cannot both be set to "True" in a TypeVar.

  Closes #​5895

• Add new check unnecessary-dunder-call for unnecessary dunder method calls.

  Closes #​5936

• unnecessary-lambda-assignment: Lambda expression assigned to a variable. Define a function using the "def" keyword instead. unnecessary-direct-lambda-call: Lambda expression called directly. Execute the expression inline instead.

  Closes #​5976

• potential-index-error: Emitted when the index of a list or tuple exceeds its length. This checker is currently quite conservative to avoid false positives. We welcome suggestions for improvements.

  Closes #​578

• Added new checker unnecessary-list-index-lookup for indexing into a list while iterating over enumerate().

  Closes #​4525

• Added new message called duplicate-value which identifies duplicate values inside sets.

  Closes #​5880

• Added the super-without-brackets checker, raised when a super call is missing its brackets.

  Closes #​4008

Removed checkers

• The no-init (W0232) warning has been removed. It's ok to not have an __init__ in a class.

  Closes #​2409

• Removed the assign-to-new-keyword message as there are no new keywords in the supported Python versions any longer.

  Closes #​4683

• Moved no-self-use check to optional extension. You now need to explicitly enable this check using load-plugins=pylint.extensions.no_self_use.

  Closes #​5502

Extensions

• RedefinedLoopNameChecker

  • Added optional extension redefined-loop-name to emit messages when a loop variable is redefined in the loop body.

  Closes #​5072

• DocStringStyleChecker

  • Re-enable checker bad-docstring-quotes for Python <= 3.7.

  Closes #​6087

• NoSelfUseChecker

  • Added no-self-use check, previously enabled by default.

  Closes #​5502

Other Changes

• Started ignoring underscore as a local variable for too-many-locals.

  Closes #​6488

• Pylint can now be installed with an extra-require called spelling (pip install pylint[spelling]). This will add pyenchant to pylint's dependencies. You will still need to install the requirements for pyenchant (the enchant library and any dictionaries) yourself. You will also need to set the spelling-dict option.

  Refs #​6462

• Improved wording of the message of deprecated-module

  Closes #​6169

• Pylint now requires Python 3.7.2 or newer to run.

  Closes #​4301

• We made a greater effort to reraise failures stemming from the astroid library as AstroidError, with the effect that pylint emits astroid-error rather than merely fatal. Regardless, please report any such issues you encounter!

• We have improved our recognition of inline disable and enable comments. It is now possible to disable bad-option-value inline (as long as you disable it before the bad option value is raised, i.e. disable=bad-option-value,bad-message not disable=bad-message,bad-option-value ) as well as certain other previously unsupported messages.

  Closes #​3312

• The main checker name is now main instead of master. The configuration does not need to be updated as sections' name are optional.

  Closes #​5467

• Update invalid-slots-object message to show bad object rather than its inferred value.

  Closes #​6101

• Fixed a crash in the not-an-iterable checker involving multiple starred expressions inside a call.

  Closes #​6372

• Fixed a crash in the unused-private-member checker involving chained private attributes.

  Closes #​6709

• Disable spellchecking of mypy rule names in ignore directives.

  Closes #​5929

• implicit-str-concat will now be raised on calls like open("myfile.txt" "a+b") too.

  Closes #​6441

• Fix a failure to respect inline disables for fixme occurring on the last line of a module when pylint is launched with --enable=fixme.

• Removed the broken generate-man option.

  Closes #​5283 Closes #​1887

• Fixed failure to enable deprecated-module after a disable=all by making ImportsChecker solely responsible for emitting deprecated-module instead of sharing responsibility with StdlibChecker. (This could have led to double messages.)

• Added the generate-toml-config option.

  Refs #​5462

• bad-option-value will be emitted whenever a configuration value or command line invocation includes an unknown message.

  Closes #​4324

• Added the unrecognized-option message. Raised if we encounter any unrecognized options.

  Closes #​5259

• Fix false negative for bad-string-format-type if the value to be formatted is passed in as a variable holding a constant.

• The concept of checker priority has been removed.

• The cache-max-size-none checker has been renamed to method-cache-max-size-none.

  Closes #​5670

• The method-cache-max-size-none checker will now also check functools.cache.

  Closes #​5670

• BaseChecker classes now require the linter argument to be passed.

• The set_config_directly decorator has been removed.

• Don't report useless-super-delegation for the __hash__ method in classes that also override the __eq__ method.

  Closes #​3934

• Fix falsely issuing useless-suppression on the wrong-import-position checker.

  Closes #​5219

• Fixed false positive no-member for Enums with self-defined members.

  Closes #​5138

• Fix false negative for no-member when attempting to assign an instance attribute to itself without any prior assignment.

  Closes #​1555

• Changed message type from redefined-outer-name to redefined-loop-name (optional extension) for redefinitions of outer loop variables by inner loops.

  Closes #​5608

• By default the similarity checker will now ignore imports and ignore function signatures when computing duplication. If you want to keep the previous behaviour set ignore-imports and ignore-signatures to False.

• Pylint now expands the user path (i.e. ~ to home/yusef/) and expands environment variables (i.e. home/$USER/$project to home/yusef/pylint for USER=yusef and project=pylint) for pyreverse's output-directory, import-graph, ext-import-graph, int-import-graph options, and the spell checker's spelling-private-dict-file option.

  Refs #​6493

• Don't emit unsubscriptable-object for string annotations. Pylint doesn't check if class is only generic in type stubs only.

  Closes #​4369 and #​6523

• Fix pyreverse crash RuntimeError: dictionary changed size during iteration

  Refs #​6612

• Fix syntax for return type annotations in MermaidJS diagrams produced with pyreverse.

  Closes #​6467

• Fix type annotations of class and instance attributes using the alternative union syntax in pyreverse diagrams.

• Fix bug where it writes a plain text error message to stdout, invalidating output formats.

  Closes #​6597

• The refactoring checker now also raises 'consider-using-a-generator' messages for max(), min() and sum().

  Refs #​6595

• Update ranges for using-constant-test and missing-parentheses-for-call-in-test error messages.

• Don't emit no-member inside type annotations with from __future__ import annotations.

  Closes #​6594

• Fix unexpected-special-method-signature false positive for __init_subclass__ methods with one or more arguments.

  Closes #​6644

Deprecations

• The ignore-mixin-members option has been deprecated. You should now use the new ignored-checks-for-mixins option.

  Closes #​5205

• interfaces.implements has been deprecated and will be removed in 3.0. Please use standard inheritance patterns instead of __implements__.

  Refs #​2287

• All Interface classes in pylint.interfaces have been deprecated. You can subclass the respective normal classes to get the same behaviour. The __implements__ functionality was based on a rejected PEP from 2001: https://peps.python.org/pep-0245/

  Closes #​2287

• MapReduceMixin has been deprecated. BaseChecker now implements get_map_data and reduce_map_data. If a checker actually needs to reduce data it should define get_map_data as returning something different than None and let its reduce_map_data handle a list of the types returned by get_map_data. An example can be seen by looking at pylint/checkers/similar.py.

• The config attribute of BaseChecker has been deprecated. You can use checker.linter.config to access the global configuration object instead of a checker-specific object.

  Refs #​5392

• The level attribute of BaseChecker has been deprecated: everything is now displayed in --help, all the time.

  Refs #​5392

• The set_option method of BaseChecker has been deprecated. You can use checker.linter.set_option to set an option on the global configuration object instead of a checker-specific object.

  Refs #​5392

• The options_providers attribute of ArgumentsManager has been deprecated.

  Refs #​5392

• Fix saving of persistent data files in environments where the user's cache directory and the linted file are on a different drive.

  Closes #​6394

• The method-cache-max-size-none checker will now also check functools.cache.

• The config attribute of PyLinter is now of the argparse.Namespace type instead of optparse.Values.

  Refs #​5392

• UnsupportedAction has been deprecated.

  Refs #​5392

• OptionsManagerMixIn has been deprecated.

  Refs #​5392

• OptionParser has been deprecated.

  Refs #​5392

• Option has been deprecated.

  Refs #​5392

• OptionsProviderMixIn has been deprecated.

  Refs #​5392

• ConfigurationMixIn has been deprecated.

• The option_groups attribute of PyLinter has been deprecated.

  Refs #​5392

• get_global_config has been deprecated. You can now access all global options from checker.linter.config.

  Refs #​5392

• OptionsManagerMixIn has been replaced with ArgumentsManager. ArgumentsManager is considered private API and most methods that were public on OptionsManagerMixIn have now been deprecated and will be removed in a future release.

  Refs #​5392

• OptionsProviderMixIn has been replaced with ArgumentsProvider. ArgumentsProvider is considered private API and most methods that were public on OptionsProviderMixIn have now been deprecated and will be removed in a future release.

  Refs #​5392

• pylint.pyreverse.ASTWalker has been removed, as it was only used internally by a single child class.

  Refs #​6712

• pyreverse: Resolving and displaying implemented interfaces that are defined by the __implements__ attribute has been deprecated and will be removed in 3.0.

  Refs #​6713

• is_class_subscriptable_pep585_with_postponed_evaluation_enabled has been deprecated. Use is_postponed_evaluation_enabled(node) and is_node_in_type_annotation_context(node) instead.

  Refs #​6536