*************************** What's New in Pylint 2.16 *************************** .. toctree:: :maxdepth: 2 :Release: 2.16 :Date: 2023-02-01 Summary -- Release highlights ============================= In 2.16.0 we added aggregation and composition understanding in ``pyreverse``, and a way to clear the cache in between run in server mode (originally for the VS Code integration). Apart from the bug fixes there's also a lot of new checks, and new extensions that have been asked for for a long time that were implemented. If you want to benefit from all the new checks load the following plugins:: pylint.extensions.dict_init_mutate, pylint.extensions.dunder, pylint.extensions.typing, pylint.extensions.magic_value, We still welcome any community effort to help review, integrate, and add good/bad examples to the doc for `_. 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! Last but not least @clavedeluna and @nickdrozd became triagers, welcome to the team ! .. towncrier release notes start What's new in Pylint 2.16.4? ---------------------------- Release date: 2023-03-06 False Positives Fixed --------------------- - Fix false positive for isinstance-second-argument-not-valid-type with union types. Closes #8205 (`#8205 `_) What's new in Pylint 2.16.3? ---------------------------- Release date: 2023-03-03 False Positives Fixed --------------------- - Fix false positive for ``wrong-spelling-in-comment`` with class names in a python 2 type comment. Closes #8370 (`#8370 `_) Other Bug Fixes --------------- - Prevent emitting ``invalid-name`` for the line on which a ``global`` statement is declared. Closes #8307 (`#8307 `_) What's new in Pylint 2.16.2? ---------------------------- Release date: 2023-02-13 New Features ------------ - Add `--version` option to `pyreverse`. Refs #7851 (`#7851 `_) False Positives Fixed --------------------- - Fix false positive for ``used-before-assignment`` when ``typing.TYPE_CHECKING`` is used with if/elif/else blocks. Closes #7574 (`#7574 `_) - Fix false positive for ``used-before-assignment`` for named expressions appearing after the first element in a list, tuple, or set. Closes #8252 (`#8252 `_) Other Bug Fixes --------------- - Fix ``used-before-assignment`` false positive when the walrus operator is used with a ternary operator in dictionary key/value initialization. Closes #8125 (`#8125 `_) - Fix ``no-name-in-module`` false positive raised when a package defines a variable with the same name as one of its submodules. Closes #8148 (`#8148 `_) - Fix ``nested-min-max`` suggestion message to indicate it's possible to splat iterable objects. Closes #8168 (`#8168 `_) - Fix a crash happening when a class attribute was negated in the start argument of an enumerate. Closes #8207 (`#8207 `_) What's new in Pylint 2.16.1? ---------------------------- Release date: 2023-02-02 Other Bug Fixes --------------- - Fix a crash happening for python interpreter < 3.9 following a failed typing update. Closes #8161 (`#8161 `_) What's new in Pylint 2.16.0? ---------------------------- Release date: 2023-02-01 Changes requiring user actions ------------------------------ - The ``accept-no-raise-doc`` option related to ``missing-raises-doc`` will now be correctly taken into account all the time. Pylint will no longer raise missing-raises-doc (W9006) when no exceptions are documented and accept-no-raise-doc is true (issue #7208). If you were expecting missing-raises-doc errors to be raised in that case, you will now have to add ``accept-no-raise-doc=no`` in your configuration to keep the same behavior. Closes #7208 (`#7208 `_) New Features ------------ - Added the ``no-header`` output format. If enabled with ``--output-format=no-header``, it will not include the module name in the output. Closes #5362 (`#5362 `_) - Added configuration option ``clear-cache-post-run`` to support server-like usage. Use this flag if you expect the linted files to be altered between runs. Refs #5401 (`#5401 `_) - Add ``--allow-reexport-from-package`` option to configure the ``useless-import-alias`` check not to emit a warning if a name is reexported from a package. Closes #6006 (`#6006 `_) - Update ``pyreverse`` to differentiate between aggregations and compositions. ``pyreverse`` checks if it's an Instance or a Call of an object via method parameters (via type hints) to decide if it's a composition or an aggregation. Refs #6543 (`#6543 `_) New Checks ---------- - Adds a ``pointless-exception-statement`` check that emits a warning when an Exception is created and not assigned, raised or returned. Refs #3110 (`#3110 `_) - Add a ``shadowed-import`` message for aliased imports. Closes #4836 (`#4836 `_) - Add new check called ``unbalanced-dict-unpacking`` to check for unbalanced dict unpacking in assignment and for loops. Closes #5797 (`#5797 `_) - Add new checker ``positional-only-arguments-expected`` to check for cases when positional-only arguments have been passed as keyword arguments. Closes #6489 (`#6489 `_) - Added ``singledispatch-method`` which informs that ``@singledispatch`` should decorate functions and not class/instance methods. Added ``singledispatchmethod-function`` which informs that ``@singledispatchmethod`` should decorate class/instance methods and not functions. Closes #6917 (`#6917 `_) - Rename ``broad-except`` to ``broad-exception-caught`` and add new checker ``broad-exception-raised`` which will warn if general exceptions ``BaseException`` or ``Exception`` are raised. Closes #7494 (`#7494 `_) - Added ``nested-min-max`` which flags ``min(1, min(2, 3))`` to simplify to ``min(1, 2, 3)``. Closes #7546 (`#7546 `_) - Extended ``use-dict-literal`` to also warn about call to ``dict()`` when passing keyword arguments. Closes #7690 (`#7690 `_) - Add ``named-expr-without-context`` check to emit a warning if a named expression is used outside a context like ``if``, ``for``, ``while``, or a comprehension. Refs #7760 (`#7760 `_) - Add ``invalid-slice-step`` check to warn about a slice step value of ``0`` for common builtin sequences. Refs #7762 (`#7762 `_) - Add ``consider-refactoring-into-while-condition`` check to recommend refactoring when a while loop is defined with a constant condition with an immediate ``if`` statement to check for ``break`` condition as a first statement. Closes #8015 (`#8015 `_) Extensions ---------- - Add new extension checker ``dict-init-mutate`` that flags mutating a dictionary immediately after the dictionary was created. Closes #2876 (`#2876 `_) - Added ``bad-dunder-name`` extension check, which flags bad or misspelled dunder methods. You can use the ``good-dunder-names`` option to allow specific dunder names. Closes #3038 (`#3038 `_) - Added ``consider-using-augmented-assign`` check for ``CodeStyle`` extension which flags ``x = x + 1`` to simplify to ``x += 1``. This check is disabled by default. To use it, load the code style extension with ``load-plugins=pylint.extensions.code_style`` and add ``consider-using-augmented-assign`` in the ``enable`` option. Closes #3391 (`#3391 `_) - Add ``magic-number`` plugin checker for comparison with constants instead of named constants or enums. You can use it with ``--load-plugins=pylint.extensions.magic_value``. Closes #7281 (`#7281 `_) - Add ``redundant-typehint-argument`` message for `typing` plugin for duplicate assign typehints. Enable the plugin to enable the message with: ``--load-plugins=pylint.extensions.typing``. Closes #7636 (`#7636 `_) False Positives Fixed --------------------- - Fix false positive for ``unused-variable`` and ``unused-import`` when a name is only used in a string literal type annotation. Closes #3299 (`#3299 `_) - Document a known false positive for ``useless-suppression`` when disabling ``line-too-long`` in a module with only comments and no code. Closes #3368 (`#3368 `_) - ``trailing-whitespaces`` is no longer reported within strings. Closes #3822 (`#3822 `_) - Fix false positive for ``global-variable-not-assigned`` when a global variable is re-assigned via an ``ImportFrom`` node. Closes #4809 (`#4809 `_) - Fix false positive for ``use-maxsplit-arg`` with custom split method. Closes #4857 (`#4857 `_) - Fix ``logging-fstring-interpolation`` false positive raised when logging and f-string with ``%s`` formatting. Closes #4984 (`#4984 `_) - Fix false-positive for ``used-before-assignment`` in pattern matching with a guard. Closes #5327 (`#5327 `_) - Fix ``use-sequence-for-iteration`` when unpacking a set with ``*``. Closes #5788 (`#5788 `_) - Fix ``deprecated-method`` false positive when alias for method is similar to name of deprecated method. Closes #5886 (`#5886 `_) - Fix false positive ``assigning-non-slot`` when a class attribute is re-assigned. Closes #6001 (`#6001 `_) - 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 (`#6592 `_) - Fixes false positive ``abstract-method`` on Protocol classes. Closes #7209 (`#7209 `_) - Pylint now understands the ``kw_only`` keyword argument for ``dataclass``. Closes #7290, closes #6550, closes #5857 (`#7290 `_) - 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 (`#7311 `_) - Fix ``used-before-assignment`` for functions/classes defined in type checking guard. Closes #7368 (`#7368 `_) - Fix false positive for ``unhashable-member`` when subclassing ``dict`` and using the subclass as a dictionary key. Closes #7501 (`#7501 `_) - Fix the message for ``unnecessary-dunder-call`` for ``__aiter__`` and ``__aneext__``. Also only emit the warning when ``py-version`` >= 3.10. Closes #7529 (`#7529 `_) - Fix ``used-before-assignment`` false positive when else branch calls ``sys.exit`` or similar terminating functions. Closes #7563 (`#7563 `_) - Fix a false positive for ``used-before-assignment`` for imports guarded by ``typing.TYPE_CHECKING`` later used in variable annotations. Closes #7609 (`#7609 `_) - Fix a false positive for ``simplify-boolean-expression`` when multiple values are inferred for a constant. Closes #7626 (`#7626 `_) - ``unnecessary-list-index-lookup`` will not be wrongly emitted if ``enumerate`` is called with ``start``. Closes #7682 (`#7682 `_) - Don't warn about ``stop-iteration-return`` when using ``next()`` over ``itertools.cycle``. Closes #7765 (`#7765 `_) - Fixes ``used-before-assignment`` false positive when the walrus operator is used in a ternary operator. Closes #7779 (`#7779 `_) - Fix ``missing-param-doc`` false positive when function parameter has an escaped underscore. Closes #7827 (`#7827 `_) - Fixes ``method-cache-max-size-none`` false positive for methods inheriting from ``Enum``. Closes #7857 (`#7857 `_) - ``multiple-statements`` no longer triggers for function stubs using inlined ``...``. Closes #7860 (`#7860 `_) - Fix a false positive for ``used-before-assignment`` when a name guarded by ``if TYPE_CHECKING:`` is used as a type annotation in a function body and later re-imported in the same scope. Closes #7882 (`#7882 `_) - Prevent ``used-before-assignment`` when imports guarded by ``if TYPE_CHECKING`` are guarded again when used. Closes #7979 (`#7979 `_) - Fixes false positive for ``try-except-raise`` with multiple exceptions in one except statement if exception are in different namespace. Closes #8051 (`#8051 `_) - Fix ``invalid-name`` errors for ``typing_extension.TypeVar``. Refs #8089 (`#8089 `_) - Fix ``no-kwoa`` false positive for context managers. Closes #8100 (`#8100 `_) - Fix a false positive for ``redefined-variable-type`` when ``async`` methods are present. Closes #8120 (`#8120 `_) False Negatives Fixed --------------------- - Code following a call to ``quit``, ``exit``, ``sys.exit`` or ``os._exit`` will be marked as `unreachable`. Refs #519 (`#519 `_) - Emit ``used-before-assignment`` when function arguments are redefined inside an inner function and accessed there before assignment. Closes #2374 (`#2374 `_) - Fix a false negative for ``unused-import`` when one module used an import in a type annotation that was also used in another module. Closes #4150 (`#4150 `_) - Flag ``superfluous-parens`` if parentheses are used during string concatenation. Closes #4792 (`#4792 `_) - Emit ``used-before-assignment`` when relying on names only defined under conditions always testing false. Closes #4913 (`#4913 `_) - ``consider-using-join`` can now be emitted for non-empty string separators. Closes #6639 (`#6639 `_) - Emit ``used-before-assignment`` for further imports guarded by ``TYPE_CHECKING`` Previously, this message was only emitted for imports guarded directly under ``TYPE_CHECKING``, not guarded two if-branches deep, nor when ``TYPE_CHECKING`` was imported from ``typing`` under an alias. Closes #7539 (`#7539 `_) - Fix a false negative for ``unused-import`` when a constant inside ``typing.Annotated`` was treated as a reference to an import. Closes #7547 (`#7547 `_) - ``consider-using-any-or-all`` message will now be raised in cases when boolean is initialized, reassigned during loop, and immediately returned. Closes #7699 (`#7699 `_) - Extend ``invalid-slice-index`` to emit an warning for invalid slice indices used with string and byte sequences, and range objects. Refs #7762 (`#7762 `_) - Fixes ``unnecessary-list-index-lookup`` false negative when ``enumerate`` is called with ``iterable`` as a kwarg. Closes #7770 (`#7770 `_) - ``no-else-return`` or ``no-else-raise`` will be emitted if ``except`` block always returns or raises. Closes #7788 (`#7788 `_) - Fix ``dangerous-default-value`` false negative when ``*`` is used. Closes #7818 (`#7818 `_) - ``consider-using-with`` now triggers for ``pathlib.Path.open``. Closes #7964 (`#7964 `_) Other Bug Fixes --------------- - Fix bug in detecting ``unused-variable`` when iterating on variable. Closes #3044 (`#3044 `_) - 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 (`#3299 `_) - Update ``disallowed-name`` check to flag module-level variables. Closes #3701 (`#3701 `_) - Pylint will no longer deadlock if a parallel job is killed but fail immediately instead. Closes #3899 (`#3899 `_) - Fix ignored files being linted when passed on stdin. Closes #4354 (`#4354 `_) - Fix ``no-member`` false negative when augmented assign is done manually, without ``+=``. Closes #4562 (`#4562 `_) - Any assertion on a populated tuple will now receive a ``assert-on-tuple`` warning. Closes #4655 (`#4655 `_) - ``missing-return-doc``, ``missing-raises-doc`` and ``missing-yields-doc`` now respect the ``no-docstring-rgx`` option. Closes #4743 (`#4743 `_) - Update ``reimported`` help message for clarity. Closes #4836 (`#4836 `_) - ``consider-iterating-dictionary`` will no longer be raised if bitwise operations are used. Closes #5478 (`#5478 `_) - Using custom braces in ``msg-template`` will now work properly. Closes #5636 (`#5636 `_) - Pylint will now filter duplicates given to it before linting. The output should be the same whether a file is given/discovered multiple times or not. Closes #6242, #4053 (`#6242 `_) - Remove ``__index__`` dunder method call from ``unnecessary-dunder-call`` check. Closes #6795 (`#6795 `_) - Fixed handling of ``--`` as separator between positional arguments and flags. This was not actually fixed in 2.14.5. Closes #7003, Refs #7096 (`#7003 `_) - Don't crash on ``OSError`` in config file discovery. Closes #7169 (`#7169 `_) - Messages sent to reporter are now copied so a reporter cannot modify the message sent to other reporters. Closes #7214 (`#7214 `_) - 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. (`#7264 `_) - Update ``modified_iterating`` checker to fix a crash with ``for`` loops on empty list. Closes #7380 (`#7380 `_) - Update wording for ``arguments-differ`` and ``arguments-renamed`` to clarify overriding object. Closes #7390 (`#7390 `_) - ``disable-next`` is now correctly scoped to only the succeeding line. Closes #7401 (`#7401 `_) - Fixed a crash in the ``unhashable-member`` checker when using a ``lambda`` as a dict key. Closes #7453 (`#7453 `_) - Add ``mailcap`` to deprecated modules list. Closes #7457 (`#7457 `_) - Fix a crash in the ``modified-iterating-dict`` checker involving instance attributes. Closes #7461 (`#7461 `_) - ``invalid-class-object`` does not crash anymore when ``__class__`` is assigned alongside another variable. Closes #7467 (`#7467 `_) - ``--help-msg`` now accepts a comma-separated list of message IDs again. Closes #7471 (`#7471 `_) - Allow specifying non-builtin exceptions in the ``overgeneral-exception`` option using an exception's qualified name. Closes #7495 (`#7495 `_) - Report ``no-self-argument`` rather than ``no-method-argument`` for methods with variadic arguments. Closes #7507 (`#7507 `_) - Fixed an issue where ``syntax-error`` couldn't be raised on files with invalid encodings. Closes #7522 (`#7522 `_) - Fix false positive for ``redefined-outer-name`` when aliasing ``typing`` e.g. as ``t`` and guarding imports under ``t.TYPE_CHECKING``. Closes #7524 (`#7524 `_) - Fixed a crash of the ``modified_iterating`` checker when iterating on a set defined as a class attribute. Closes #7528 (`#7528 `_) - Use ``py-version`` to determine if a message should be emitted for messages defined with ``max-version`` or ``min-version``. Closes #7569 (`#7569 `_) - Improve ``bad-thread-instantiation`` check to warn if ``target`` is not passed in as a keyword argument or as a second argument. Closes #7570 (`#7570 `_) - Fixes edge case of custom method named ``next`` raised an astroid error. Closes #7610 (`#7610 `_) - 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. (`#7635 `_) - Fix crash that happened when parsing files with unexpected encoding starting with 'utf' like ``utf13``. Closes #7661 (`#7661 `_) - Fix a crash when a child class with an ``__init__`` method inherits from a parent class with an ``__init__`` class attribute. Closes #7742 (`#7742 `_) - Fix ``valid-metaclass-classmethod-first-arg`` default config value from "cls" to "mcs" which would cause both a false-positive and false-negative. Closes #7782 (`#7782 `_) - Fixes a crash in the ``unnecessary_list_index_lookup`` check when using ``enumerate`` with ``start`` and a class attribute. Closes #7821 (`#7821 `_) - Fixes a crash in ``stop-iteration-return`` when the ``next`` builtin is called without arguments. Closes #7828 (`#7828 `_) - When pylint exit due to bad arguments being provided the exit code will now be the expected ``32``. Refs #7931 (`#7931 `_) - Fixes a ``ModuleNotFound`` exception when running pylint on a Django project with the ``pylint_django`` plugin enabled. Closes #7938 (`#7938 `_) - Fixed a crash when inferring a value and using its qname on a slice that was being incorrectly called. Closes #8067 (`#8067 `_) - Use better regex to check for private attributes. Refs #8081 (`#8081 `_) - Fix issue with new typing Union syntax in runtime context for Python 3.10+. Closes #8119 (`#8119 `_) Other Changes ------------- - Pylint now provides basic support for Python 3.11. Closes #5920 (`#5920 `_) - Update message for ``abstract-method`` to include child class name. Closes #7124 (`#7124 `_) - Update Pyreverse's dot and plantuml printers to detect when class methods are abstract and show them with italic font. For the dot printer update the label to use html-like syntax. Closes #7346 (`#7346 `_) - The ``docparams`` extension now considers typing in Numpy style docstrings as "documentation" for the ``missing-param-doc`` message. Refs #7398 (`#7398 `_) - Relevant ``DeprecationWarnings`` are now raised with ``stacklevel=2``, so they have the callsite attached in the message. Closes #7463 (`#7463 `_) - Add a ``minimal`` option to ``pylint-config`` and its toml generator. Closes #7485 (`#7485 `_) - Add method name to the error messages of ``no-method-argument`` and ``no-self-argument``. Closes #7507 (`#7507 `_) - Prevent leaving the pip install cache in the Docker image. Refs #7544 (`#7544 `_) - Add a keyword-only ``compare_constants`` argument to ``safe_infer``. Refs #7626 (`#7626 `_) - Add ``default_enabled`` option to optional message dict. Provides an option to disable a checker message by default. To use a disabled message, the user must enable it explicitly by adding the message to the ``enable`` option. Refs #7629 (`#7629 `_) - Sort ``--generated-rcfile`` output. Refs #7655 (`#7655 `_) - epylint is now deprecated and will be removed in pylint 3.0.0. All emacs and flymake related files were removed and their support will now happen in an external repository : https://github.com/emacsorphanage/pylint. Closes #7737 (`#7737 `_) - Adds test for existing preferred-modules configuration functionality. Refs #7957 (`#7957 `_) Internal Changes ---------------- - Add and fix regression tests for plugin loading. This shores up the tests that cover the loading of custom plugins as affected by any changes made to the ``sys.path`` during execution of an ``init-hook``. Given the existing contract of allowing plugins to be loaded by fiddling with the path in this way, this is now the last bit of work needed to close Github issue #7264. Closes #7264 (`#7264 `_)