Summary -- Release highlights

In 2.13, we introduced a new check to deal with unicode security issues. On top of that a lot of work was done inside the unicode checker by @CarliJoy. We also introduced a new check when importing private name and for unnecessary ellipsis among other.

We fixed long standing issues related to duplicate code that could not be disabled, line numbers that were not accurate some of the time, and added the ability to lint all files in a directory without specifying each one. One of the most anticipated issue from the repository. Thank you @matusvalo !

A lot of undefined-variables and used-before-assignment issues were resolved thanks to @jacobtylerwalls.

We started integrating pylint-error the documentation created by @vald-phoenix a developer from Hlyniane, Ukraine. We hope he's doing well despite the current situation. The deployment is set up but there's still a lot to do so we welcome any community effort help to review, integrate, and add good/bad examples. This should be doable without any pylint or astroid knowledge, so this is the perfect entrypoint if you want to contribute to pylint without investing any time learning the internals.

This release is the last one to support interpreter below 3.7.2, 3.6 end of life was reached in december 2021.

New checkers

  • Added several checkers to deal with unicode security issues (see Trojan Sources and PEP 672 for details) that also concern the readability of the code. In detail the following checks were added:

    • bad-file-encoding checks that the file is encoded in UTF-8 as suggested by PEP8. UTF-16 and UTF-32 are not supported by Python at the moment. If this ever changes invalid-unicode-codec checks that they aren't used, to allow for backwards compatibility.

    • bidirectional-unicode checks for bidirectional unicode characters that could make code execution different than what the user expects.

    • invalid-character-backspace, invalid-character-carriage-return, invalid-character-sub, invalid-character-esc, invalid-character-zero-width-space and invalid-character-nul to check for possibly harmful unescaped characters.

    Closes #5281

  • unnecessary-ellipsis: Emitted when the ellipsis constant is used unnecessarily.

    Closes #5460

  • Added new checker typevar-name-missing-variance. Emitted when a covariant or contravariant TypeVar does not end with _co or _contra respectively or when a TypeVar is not either but has a suffix.

  • Add modified-iterating-list, modified-iterating-dict, and modified-iterating-set, emitted when items are added to or removed from respectively a list, dictionary or set being iterated through.

    Closes #5348

  • Add checker redefined-slots-in-subclass: Emitted when a slot is redefined in a subclass.

    Closes #5617

  • Rewrote Checker of non-ascii-name.

    It now ensures __all__ Python names are ASCII and also properly checks the names of imports (non-ascii-module-import) as well as file names (non-ascii-file-name) and emits their respective new warnings.

    Non ASCII characters could be homoglyphs (look alike characters) and hard to enter on a non specialized keyboard. See Confusable Characters in PEP 672

  • Added cache-max-size-none checker with checks for the use of functools.lru_cache on class methods with a maxsize of None. This is unrecommended as it creates memory leaks by never letting the instance get garbage collected.

    Closes #5670 Clsoes #6180

Removed checkers

  • Removed the deprecated check_docs extension. You can use the docparams checker to get the checks previously included in check_docs.

    Closes #5322


  • New extension import-private-name: indicate imports of external private packages and objects (prefixed with _). It can be loaded using load-plugins=pylint.extensions.private_import.

    Closes #5463

  • Pyreverse - add output in mermaid-js format and html which is an mermaid js diagram with html boilerplate

  • TypingChecker

  • DocstringParameterChecker

    • Fixed incorrect classification of Numpy-style docstring as Google-style docstring for docstrings with property setter documentation. Docstring classification is now based on the highest amount of matched sections instead of the order in which the docstring styles were tried.

  • DocStringStyleChecker

    • Disable checker bad-docstring-quotes for Python <= 3.7, because in these versions the line numbers for decorated functions and classes are not reliable which interferes with the checker.

    Closes #3077

Other Changes

  • Include testing_pylintrc in source and wheel distributions.

    Closes #6028

  • Fix false positive for unused-import when disabling both used-before-assignment and undefined-variable.

    Closes #6089

  • Fix false positive for unnecessary-ellipsis when using an ellipsis as a default argument.

    Closes #5973

  • Add missing dunder methods to unexpected-special-method-signature check.

  • No longer emit no-member in for loops that reference self if the binary operation that started the for loop uses a self that is encapsulated in tuples or lists.

    Refs pylint-dev/astroid#1360 Closes #4826

  • Fix matching --notes options that end in a non-word character.

    Closes #5840

  • The line numbering for messages related to function arguments is now more accurate. This can require some message disables to be relocated to updated positions.

  • using-f-string-in-unsupported-version and using-final-decorator-in-unsupported-version msgids

    were renamed from W1601 and W1602 to W2601 and W2602. Disables using these msgids will break. This is done in order to restore consistency with the already existing msgids for apply-builtin and basestring-builtin from the now deleted python 3K+ checker. There is now a check that we're not using existing msgids or symbols from deleted checkers.

    Closes #5729

  • Add --recursive option to allow recursive discovery of all modules and packages in subtree. Running pylint with --recursive=y option will check all discovered .py files and packages found inside subtree of directory provided as parameter to pylint.

    Closes #352

  • Updated the position of messages for class and function definitions to no longer cover the complete definition. Only the def or class + the name of the class/function are covered.

    Closes #5466

  • Reinstated checks from the python3 checker that are still useful for python 3 (eq-without-hash). This is now in the pylint.extensions.eq_without_hash optional extension.

    Closes #5025

  • Fix false-negative for assignment-from-none checker with list.sort() method.

    Closes #5722

  • Fix unused-private-member false positive when accessing private methods through property.

    Closes #4756

  • Fixed crash from arguments-differ and arguments-renamed when methods were defined outside the top level of a class.

    Closes #5648

  • Better warning messages for useless else or elif when a function returns early.

    Closes #5614

  • Asterisks are no longer required in Sphinx and Google style parameter documentation for missing-param-doc and are parsed correctly.

    Closes #5815 Closes #5406

  • Fixed an AstroidError in 2.13.0 raised by the `duplicate-code` checker with ignore-imports or ignore-signatures enabled.

    Closes #6301

  • Use the tomli package instead of toml to parse .toml files.

    Closes #5885

  • Fixed false positive consider-using-dict-comprehension when creating a dict using a list of tuples where key AND value vary depending on the same condition.

    Closes #5588

  • When run in parallel mode pylint now pickles the data passed to subprocesses with the dill package. The dill package has therefore been added as a dependency.

  • Fixed false positive for global-variable-undefined when global is used with a class name

    Closes #3088

  • Fixed crash on properties and inherited class methods when comparing them for equality against an empty dict.

    Closes #5646

  • By default, pylint does no longer take files starting with .# into account. Those are considered Emacs file locks. This behavior can be reverted by redefining the ignore-patterns option.

    Closes #367

  • Fix super-init-not-called when parent or self is a Protocol

    Closes #4790

  • The issue template for crashes is now created for crashes which were previously not covered by this mechanism.

    Closes #5668

  • An astroid issue where symlinks were not being taken into account was fixed

    Closes #1470 Closes #3499 Closes #4302 Closes #4798 Closes #5081

  • Fix false negative for undefined-variable and related variable messages when the same undefined variable is used as a type annotation and is accessed multiple times, or is used as a default argument to a function.

    Closes #5399

  • Emit used-before-assignment instead of undefined-variable when attempting to access unused type annotations.

    Closes #5713

  • Fixed an issue where ungrouped-imports could not be disabled without raising useless-suppression.

    Refs #2366

  • Fixed a crash on __init__ nodes when the attribute was previously uninferable due to a cache limit size. This limit can be hit when the inheritance pattern of a class (and therefore of the __init__ attribute) is very large.

    Closes #5679

  • Fixed extremely long processing of long lines with comma's.

    Closes #5483

  • Fix false positive super-init-not-called for classes that inherit their init from a parent.

    Closes #4941

  • Fix false positives for used-before-assignment from using named expressions in a ternary operator test and using that expression as a call argument.

    Closes #5177, #5212

  • Fixed crash with recursion error for inference of class attributes that referenced the class itself.

    Closes #5408 Refs pylint-dev/astroid#1392

  • Fixed false positive for unused-argument when a method overridden in a subclass does nothing with the value of a keyword-only argument.

    Closes #5771 Refs pylint-dev/astroid#1382

  • Optimize parsing of long lines when missing-final-newline is enabled.

    Closes #5724

  • Fix false positive for used-before-assignment from a class definition nested under a function subclassing a class defined outside the function.

    Closes #4590

  • Fix unnecessary_dict_index_lookup false positive when deleting a dictionary's entry.

    Closes #4716

  • Fix false positive for used-before-assignment when an except handler shares a name with a test in a filtered comprehension.

    Closes #5817

  • Fix a crash in unused-private-member checker when analyzing code using type(self) in bound methods.

    Closes #5569

  • Fix crash in unnecessary-dict-index-lookup checker if the output of items() is assigned to a 1-tuple.

    Closes #5504

  • Fixed crash with slots assignments and annotated assignments.

    Closes #5479

  • Fixed a crash in unspecified-encoding checker when providing None to the mode argument of an open() call.

    Closes #5731

  • Fixed a crash involving a NewType named with an f-string.

    Closes #5770 Refs pylint-dev/astroid#1400

  • Improved bad-open-mode message when providing None to the mode argument of an open() call.

    Closes #5733

  • Fix false negative for consider-iterating-dictionary during membership checks encapsulated in iterables or not in checks

    Closes #5323

  • Allow disabling duplicate-code with a disable comment when running through pylint.

    Closes #214

  • Fix false positive for undefined-variable when namedtuple class attributes are used as return annotations.

    Closes #5568

  • Added confidence level CONTROL_FLOW for warnings relying on assumptions about control flow.

  • used-before-assignment now considers that assignments in a try block may not have occurred when the except or finally blocks are executed.

    Closes #85, #2615

  • Fixed false negative for used-before-assignment when a conditional or context manager intervened before the try statement that suggested it might fail.

    Closes #4045

  • Fixed false negative for used-before-assignment in finally blocks if an except handler did not define the assignment that might have failed in the try block.

  • Fix a false positive for assigning-non-slot when the slotted class defined __setattr__.

    Closes #3793

  • Fixed a false positive for invalid-class-object when the object being assigned to the __class__ attribute is uninferable.

  • Added a testutil extra require to the packaging, as gitpython should not be a dependency all the time but is still required to use the primer helper code in pylint.testutil. You can install it with pip install pylint[testutil].

    Closes #5486

  • Fixed a false positive for used-before-assignment when a named expression appears as the first value in a container.

    Closes #5112

  • Fixed false positive for used-before-assignment with self-referential type annotation in conditional statements within class methods.

    Closes #5499

  • used-before-assignment now assumes that assignments in except blocks may not have occurred and warns accordingly.

    Closes #4761

  • When evaluating statements after an except block, used-before-assignment assumes that assignments in the except blocks took place if the corresponding try block contained a return statement.

    Closes #5500

  • Fixed a false negative for used-before-assignment when some but not all except handlers defined a name relied upon after an except block when the corresponding try block contained a return statement.

    Closes #5524

  • When evaluating statements in the else clause of a loop, used-before-assignment assumes that assignments in the except blocks took place if the except handlers constituted the only ways for the loop to finish without breaking early.

    Closes #5683

  • used-before-assignment now checks names in try blocks.

  • Fixed false positive with used-before-assignment for assignment expressions in lambda statements.

    Closes #5360, #3877

  • Improve invalid-name check for TypeVar names. The accepted pattern can be customized with --typevar-rgx.

    Closes #3401

  • Fixed a false positive (affecting unreleased development) for used-before-assignment involving homonyms between filtered comprehensions and assignments in except blocks.

    Closes #5586

  • Fixed crash on list comprehensions that used type as inner variable name.

    Closes #5461

  • Fixed crash in use-maxsplit-arg checker when providing the sep argument to str.split() by keyword.

    Closes #5737

  • Fix false positive for unused-variable for a comprehension variable matching an outer scope type annotation.

    Closes #5326

  • Fix false negative for undefined-variable for a variable used multiple times in a comprehension matching an unused outer scope type annotation.

    Closes #5654

  • Require Python 3.6.2 to run pylint.

    Closes #5065

  • Fixed crash on uninferable decorators on Python 3.6 and 3.7

  • Emit redefined-outer-name when a nested except handler shadows an outer one.

    Closes #4434 Closes #5370

  • encoding can now be supplied as a positional argument to calls that open files without triggering unspecified-encoding.

    Closes #5638

  • Fatal errors now emit a score of 0.0 regardless of whether the linted module contained any statements

    Closes #5451

  • fatal was added to the variables permitted in score evaluation expressions.

  • The default score evaluation now uses a floor of 0.

    Closes #2399

  • Fix comparison-with-callable false positive for callables that raise, such as typing constants.

    Closes #5557

  • When invoking pylint, epylint, symilar or pyreverse by importing them in a python file you can now pass an argv keyword besides patching sys.argv.

    Closes #5320

  • The PyLinter class will now be initialized with a TextReporter as its reporter if none is provided.

  • Fix false positive not-callable with attributes that alias NamedTuple

    Fixes part of #1730

  • The testutils for unittests now accept end_lineno and end_column. Tests without these will trigger a DeprecationWarning.

  • arguments-differ will no longer complain about method redefinitions with extra parameters that have default values.

    Closes #1556, #5338

  • Disables for deprecated-module and similar warnings for stdlib features deprecated in newer versions of Python no longer raise useless-suppression when linting with older Python interpreters where those features are not yet deprecated.

  • Importing the deprecated stdlib module xml.etree.cElementTree now emits deprecated_module.

    Closes #5862

  • Importing the deprecated stdlib module distutils now emits deprecated_module on Python 3.10+.

  • Fixed false positive unexpected-keyword-arg for decorators.

    Closes #258

  • missing-raises-doc will now check the class hierarchy of the raised exceptions

    def my_function():
      """My function.
        Exception: if something fails
      raise ValueError

    Closes #4955

  • Fixed false positive for unused-variable when a nonlocal name is assigned as part of a multi-name assignment.

    Closes #3781

  • Fix false positive - Allow unpacking of self in a subclass of typing.NamedTuple.

    Closes #5312

  • Fixed false negative unpacking-non-sequence when value is an empty list.

    Closes #5707

  • Fixed false positive for global-variable-not-assigned when the del statement is used

    Closes #5333

  • Fix type hints in class diagrams generated by pyreverse for class methods and methods returning None.

  • Output better error message if unsupported file formats are used with pyreverse.

    Closes #5950

  • Fixed false positive for unused-argument when a nonlocal name is used in a nested function that is returned without being called by its parent.

    Closes #5187

  • Avoid emitting raising-bad-type when there is inference ambiguity on the variable being raised.

    Closes #2793

  • Fix false positive for superfluous-parens for patterns like "return (a or b) in iterable".

    Closes #5803

  • Fix a crash in the unsupported-membership-test checker when assigning multiple constants to class attributes including __iter__ via unpacking.

    Closes #6366

  • Fix false positive for used-before-assignment for assignments taking place via nonlocal declarations after an earlier type annotation.

    Closes #5394

  • Fixed a false positive for unused-variable when a builtin specified in --additional-builtins is given a type annotation.

    Closes #6388

  • Fix false positive for 'nonexistent-operator' when repeated '-' are separated (e.g. by parens).

    Closes #5769

  • Fix a false positive for undefined-loop-variable when the else of a for loop raises or returns.

    Closes #5971

  • Only raise not-callable when all the inferred values of a property are not callable.

    Closes #5931

  • Fix false positive for unused-variable for classes inside functions and where a metaclass is provided via a call.

    Closes #4020

  • Avoid reporting superfluous-parens on expressions using the is not operator.

    Closes #5930

  • Fix a false positive for undefined-loop-variable for a variable used in a lambda inside the first of multiple loops.

    Closes #6419

  • Fix false positive for unsubscriptable-object in Python 3.8 and below for statements guarded by if TYPE_CHECKING.

    Closes #3979

  • Fix a crash when accessing __code__ and assigning it to a variable.

    Closes #6539

  • Fix a crash when linting a file that passes an integer mode= to open

    Closes #6414

  • Fix false positives for no-name-in-module and import-error for numpy.distutils and pydantic.

    Closes #6497

  • Fix IndexError crash in uninferable_final_decorators method.

    Refs #6531

  • Fix a crash in unnecessary-dict-index-lookup when subscripting an attribute.

    Closes #6557

  • Fix a false positive for undefined-loop-variable when using enumerate().

    Closes #6593