v3.2.1

What's new in Pylint 3.2.1?

Release date: 2024-05-18

False Positives Fixed

• Exclude if/else branches containing terminating functions (e.g. sys.exit())
  from possibly-used-before-assignment checks.

  Closes #9627

• Don't emit typevar-name-incorrect-variance warnings for PEP 695 style TypeVars.
  The variance is inferred automatically by the type checker.
  Adding _co or _contra suffix can help to reason about TypeVar.

  Refs #9638

• Fix a false positive for possibly-used-before-assignment when using
  typing.assert_never() (3.11+) to indicate exhaustiveness.

  Closes #9643

Other Bug Fixes

• Fix a false negative for --ignore-patterns when the directory to be linted is specified using a dot(.) and all files are ignored instead of only the files whose name begin with a dot.

  Closes #9273

• Restore "errors / warnings by module" section to report output (with -ry).

  Closes #9145

• trailing-comma-tuple should now be correctly emitted when it was disabled globally
  but enabled via local message control, after removal of an over-optimisation.

  Refs #9608

• Add --prefer-stubs=yes option to opt-in to the astroid 3.2 feature
  that prefers .pyi stubs over same-named .py files. This has the
  potential to reduce no-member errors but at the cost of more errors
  such as not-an-iterable from function bodies appearing as ....

  Defaults to no.

  Closes #9626
  Closes #9623

Internal Changes

• Update astroid version to 3.2.1. This solves some reports of RecursionError
  and also makes the prefer .pyi stubs feature in astroid 3.2.0 opt-in
  with the aforementioned --prefer-stubs=y option.

  Refs #9139

v3.2.0

What's new in Pylint 3.2.0?

Release date: 2024-05-14

Of note: a github reporter, two new checks (possibly-used-before-assignment and contextmanager-generator-missing-cleanup), performance improvements, and an astroid upgrade providing support for @overload and .pyi stubs.

New Features

• Understand six.PY2 and six.PY3 for conditional imports.

  Closes #3501

• A new github reporter has been added. This reporter returns the output of pylint in a format that
  Github can use to automatically annotate code. Use it with pylint --output-format=github on your Github Workflows.

  Closes #9443.

New Checks

• Add check possibly-used-before-assignment when relying on names after an if/else
  switch when one branch failed to define the name, raise, or return.

  Closes #1727

• Checks for generators that use contextmanagers that don't handle cleanup properly.
  Is meant to raise visibilty on the case that a generator is not fully exhausted and the contextmanager is not cleaned up properly.
  A contextmanager must yield a non-constant value and not handle cleanup for GeneratorExit.
  The using generator must attempt to use the yielded context value with x() as y and not just with x().

  Closes #2832

False Negatives Fixed

• If and Try nodes are now checked for useless return statements as well.

  Closes #9449.

• Fix false negative for property-with-parameters in the case of parameters which are positional-only, keyword-only, variadic positional or variadic keyword.

  Closes #9584

False Positives Fixed

• pylint now understands the @overload decorator return values better.

  Closes #4696
  Refs #9606

Performance Improvements

• Ignored modules are now not checked at all, instead of being checked and then
  ignored. This should speed up the analysis of large codebases which have
  ignored modules.

  Closes #9442

• ImportChecker's logic has been modified to avoid context files when possible. This makes it possible
  to cache module searches on astroid and reduce execution times.

  Refs #9310.

• An internal check for trailing-comma-tuple being enabled for a file or not is now
  done once per file instead of once for each token.

  Refs #9608.

v3.1.1

What's new in Pylint 3.1.1?

Release date: 2024-05-13

False Positives Fixed

• Treat attrs.define and attrs.frozen as dataclass decorators in
  too-few-public-methods check.

  Closes #9345

• Fix a false positive with singledispatchmethod-function when a method is decorated with both functools.singledispatchmethod and staticmethod.

  Closes #9531

• Fix a false positive for consider-using-dict-items when iterating using keys() and then deleting an item using the key as a lookup.

  Closes #9554

v3.1.0

Two new checks--use-yield-from, deprecated-attribute-- and a smattering of bug fixes.

New Features

• Skip consider-using-join check for non-empty separators if an suggest-join-with-non-empty-separator option is set to no.

  Closes #8701

• Discover .pyi files when linting.

  These can be ignored with the ignore-patterns setting.

  Closes #9097

• Check TypeAlias and TypeVar (PEP 695) nodes for invalid-name.

  Refs #9196

• Support for resolving external toml files named pylintrc.toml and .pylintrc.toml.

  Closes #9228

• Check for .clear, .discard, .pop and remove methods being called on a set while it is being iterated over.

  Closes #9334

New Checks

• New message use-yield-from added to the refactoring checker. This message is emitted when yielding from a loop can be replaced by yield from.

  Closes #9229.

• Added a deprecated-attribute message to check deprecated attributes in the stdlib.

  Closes #8855

False Positives Fixed

• Fixed false positive for inherit-non-class for generic Protocols.

  Closes #9106

• Exempt TypedDict from typing_extensions from too-many-ancestor checks.

  Refs #9167

False Negatives Fixed

• Extend broad-exception-raised and broad-exception-caught to except*.

  Closes #8827

• Fix a false-negative for unnecessary if blocks using a different than expected ordering of arguments.

  Closes #8947.

Other Bug Fixes

• Improve the message provided for wrong-import-order check. Instead of the import statement ("import x"), the message now specifies the import that is out of order and which imports should come after it. As reported in the issue, this is particularly helpful if there are multiple imports on a single line that do not follow the PEP8 convention.

  The message will report imports as follows:
  For "import X", it will report "(standard/third party/first party/local) import X"
  For "import X.Y" and "from X import Y", it will report "(standard/third party/first party/local) import X.Y"
  The import category is specified to provide explanation as to why pylint has issued the message and guidence to the developer on how to fix the problem.

  Closes #8808

Other Changes

• Print how many files were checked in verbose mode.

  Closes #8935

• Fix a crash when an enum class which is also decorated with a dataclasses.dataclass decorator is defined.

  Closes #9100

Internal Changes

• Update astroid version to 3.1.0.

  Refs #9457

v3.0.4

False Positives Fixed

• used-before-assignment is no longer emitted when using a name in a loop and
  depending on an earlier name assignment in an except block paired with
  else: continue.

  Closes #6804

• Avoid false positives for no-member involving function
  attributes supplied by decorators.

  Closes #9246

• Fixed false positive nested-min-max for nested lists.

  Closes #9307

• Fix false positive for used-before-assignment in a finally block
  when assignments took place in both the try block and each exception handler.

  Closes #9451

Other Bug Fixes

• Catch incorrect ValueError "generator already executing" for Python 3.12.0 - 3.12.2.
  This is fixed upstream in Python 3.12.3.

  Closes #9138

v3.0.3

What's new in Pylint 3.0.3?

Release date: 2023-12-11

False Positives Fixed

• Fixed false positive for unnecessary-lambda when the call has keyword arguments but not the lambda.

  Closes #9148

• Fixed incorrect suggestion for shallow copy in unnecessary-comprehension

  Example of the suggestion:
  #pylint: disable=missing-module-docstring
  a = [1, 2, 3]
  b = [x for x in a]
  b[0] = 0
  print(a) # [1, 2, 3]

  After changing b = [x for x in a] to b = a based on the suggestion, the script now prints [0, 2, 3]. The correct suggestion should be use list(a) to preserve the original behavior.

  Closes #9172

• Fix false positives for undefined-variable and unused-argument for
  classes and functions using Python 3.12 generic type syntax.

  Closes #9193

• Fixed pointless-string-statement false positive for docstrings
  on Python 3.12 type aliases.

  Closes #9268

• Fix false positive for invalid-exception-operation when concatenating tuples
  of exception types.

  Closes #9288

Other Bug Fixes

• Fix a bug where pylint was unable to walk recursively through a directory if the
  directory has an __init__.py file.

  Closes #9210

v3.0.2

False Positives Fixed

• Fix used-before-assignment false positive for generic type syntax (PEP 695, Python 3.12).

  Closes #9110

Other Bug Fixes

• Escape special symbols and newlines in messages.

  Closes #7874

• Fixes suggestion for nested-min-max for expressions with additive operators, list and dict comprehensions.

  Closes #8524

• Fixes ignoring conditional imports with ignore-imports=y.

  Closes #8914

• Emit inconsistent-quotes for f-strings with 3.12 interpreter only if targeting pre-3.12 versions.

  Closes #9113

v3.0.1

False Positives Fixed

• Fixed false positive for inherit-non-class for generic Protocols.

  Closes #9106

Other Changes

• Fix a crash when an enum class which is also decorated with a dataclasses.dataclass decorator is defined.

  Closes #9100

v3.0.0

Pylint now support python 3.12 officially.

This long anticipated major version also provides some important usability and performance improvements, along with enacting necessary breaking changes and long-announced deprecations. The documentation of each message with an example is very close too.

The required astroid version is now 3.0.0. See the astroid changelog for additional fixes, features, and performance improvements applicable to pylint.

Our code is now fully typed. The invalid-name message no longer checks for a minimum length of 3 characters by default. Dependencies like wrapt or setuptools were removed.

A new json2 reporter has been added. It features an enriched output that is easier to parse and provides more info, here's a sample output.

{
    "messages": [
        {
            "type": "convention",
            "symbol": "line-too-long",
            "message": "Line too long (1/2)",
            "messageId": "C0301",
            "confidence": "HIGH",
            "module": "0123",
            "obj": "",
            "line": 1,
            "column": 0,
            "endLine": 1,
            "endColumn": 4,
            "path": "0123",
            "absolutePath": "0123"
        }
    ],
    "statistics": {
        "messageTypeCount": {
            "fatal": 0,
            "error": 0,
            "warning": 0,
            "refactor": 0,
            "convention": 1,
            "info": 0
        },
        "modulesLinted": 1,
        "score": 5.0
    }
}

Breaking Changes

• Enabling or disabling individual messages will now take effect even if an
  --enable=all or disable=all follows in the same configuration file
  (or on the command line).

  This means for the following example, fixme messages will now be emitted:

      pylint my_module --enable=fixme --disable=all

  To regain the prior behavior, remove the superfluous earlier option.

  Closes #3696

• Remove support for launching pylint with Python 3.7.
  Code that supports Python 3.7 can still be linted with the --py-version=3.7 setting.

  Refs #6306

• Disables placed in a try block now apply to the except block.
  Previously, they only happened to do so in the presence of an else clause.

  Refs #7767

• pyreverse now uses a new default color palette that is more colorblind friendly.
  The color scheme is taken from Paul Tol's Notes <https://personal.sron.nl/~pault/>_.
  If you prefer other colors, you can use the --color-palette option to specify custom colors.

  Closes #8251

• Everything related to the __implements__ construct was removed. It was based on PEP245
  that was proposed in 2001 and rejected in 2006.

  The capability from pyreverse to take __implements__ into account when generating diagrams
  was also removed.

  Refs #8404

• pyreverse: Support for the .vcg output format (Visualization of Compiler Graphs) has been dropped.

  Closes #8416

• The warning when the now useless old pylint cache directory (pylint.d) was
  found was removed. The cache dir is documented in
  the FAQ <https://pylint.readthedocs.io/en/latest/faq.html#where-is-the-persistent-data-stored-to-compare-between-successive-runs>_.

  Refs #8462

• Following a deprecation period, pylint.config.PYLINTRC was removed.
  Use the pylint.config.find_default_config_files generator instead.

  Closes #8862

Changes requiring user actions

• The invalid-name message no longer checks for a minimum length of 3 characters by default.
  (This was an unadvertised commingling of concerns between casing
  and name length, and users regularly reported this to be surprising.)

  If checking for a minimum length is still desired, it can be regained in two ways:

  • If you are content with a disallowed-name message (instead of
    invalid-name), then simply add the option bad-names-rgxs="^..?$",
    which will fail 1-2 character-long names. (Ensure you enable
    disallowed-name.)

  • If you would prefer an invalid-name message to be emitted, or would
    prefer finer-grained control over the circumstances in which messages are
    emitted (classes vs. methods, etc.), then avail yourself of the regex
    options described
    here <https://pylint.readthedocs.io/en/stable/user_guide/configuration/all-options.html#main-checker>.
    (In particular, take note of the commented out options in the "example
    configuration" given at the bottom of the section.) The prior regexes can
    be found in the
    pull request <https://github.com/pylint-dev/pylint/pull/8813>
    that removed the length requirements.

  Closes #2018

• The compare to empty string checker (pylint.extensions.emptystring) and the compare to
  zero checker (pylint.extensions.compare-to-zero) have been removed and their checks are
  now part of the implicit booleaness checker:

  • compare-to-zero was renamed use-implicit-booleaness-not-comparison-to-zero and
    compare-to-empty-string was renamed use-implicit-booleaness-not-comparison-to-string
    and they now need to be enabled explicitly.

  • The pylint.extensions.emptystring and pylint.extensions.compare-to-zero extensions
    no longer exist and need to be removed from the load-plugins option.

  • Messages related to implicit booleaness were made more explicit and actionable.
    This permits to make their likeness explicit and will provide better performance as they
    share most of their conditions to be raised.

  Closes #6871

• epylint was removed. It now lives at: https://github.com/emacsorphanage/pylint.

  Refs #7737

• The overgeneral-exceptions option now only takes fully qualified names
  into account (builtins.Exception not Exception). If you overrode
  this option, you need to use the fully qualified name now.

  There's still a warning, but it will be removed in 3.1.0.

  Refs #8411

• Following a deprecation period, it's no longer possible to use MASTER
  or master as configuration section in setup.cfg or tox.ini. It's bad practice
  to not start a section title with the tool name. Please use pylint.main instead.

  Refs #8465

• Package stats are now printed when running Pyreverse and a --verbose flag was added to get the original output with parsed modules. You might need to activate the verbose option if you want to keep the old output.

  Closes #8973

New Features

• A new json2 reporter has been added. It features a more enriched output that is
  easier to parse and provides more info.

  Compared to json the only changes are that messages are now under the "messages"
  key and that "message-id" now follows the camelCase convention and is renamed to
  "messageId".
  The new reporter also reports the "score" of the modules you linted as defined by the
  evaluation option and provides statistics about the modules you linted.

  We encourage users to use the new reporter as the json reporter will no longer
  be maintained.

  Closes #4741

• In Pyreverse package dependency diagrams, show when a module imports another only for type-checking.

  Closes #8112

• Add new option (--show-stdlib, -L) to pyreverse.
  This is similar to the behavior of --show-builtin in that standard library
  modules are now not included by default, and this option will include them.

  Closes #8181

• Add Pyreverse option to exclude standalone nodes from diagrams with --no-standalone.

  Closes #8476

New Checks

• Added DataclassChecker module and invalid-field-call checker to check for invalid dataclasses.field() usage.

  Refs #5159

• Add return-in-finally to emit a message if a return statement was found in a finally clause.

  Closes #8260

• Add a new checker kwarg-superseded-by-positional-arg to warn when a function is called with a keyword argument which shares a name with a positional-only parameter and the function contains a keyword variadic parameter dictionary. It may be surprising behaviour when the keyword argument is added to the keyword variadic parameter dictionary.

  Closes #8558

Extensions

• Add new prefer-typing-namedtuple message to the CodeStyleChecker to suggest
  rewriting calls to collections.namedtuple as classes inheriting from typing.NamedTuple
  on Python 3.6+.

  Requires load-plugins=pylint.extensions.code_style and enable=prefer-typing-namedtuple to be raised.

  Closes #8660

False Positives Fixed

• Extend concept of "function ambiguity" in safe_infer() from
  differing number of function arguments to differing set of argument names.

  Solves false positives in tensorflow.

  Closes #3613

• Fix unused-argument false positive when __new__ does not use all the arguments of __init__.

  Closes #3670

• Fix a false positive for invalid-name when a type-annotated class variable in an enum.Enum class has no assigned value.

  Refs #7402

• Fix unused-import false positive for usage of six.with_metaclass.

  Closes #7506

• Fix false negatives and false positives for too-many-try-statements,
  too-complex, and too-many-branches by correctly counting statements
  under a try.

  Refs #7767

• When checking for unbalanced dict unpacking in for-loops, Pylint will now test whether the length of each value to be
  unpacked matches the number of unpacking targets. Previously, Pylint would test the number of values f...

v3.0.0b0

3.0.0b0 is a beta release using the new astroid 3.0.0. Expect no more breaking changes before the official 3.0.0 release, and almost no changes from 3.0.0a7. We're aiming for a release for when python 3.12 is officially out (in 2 days, 2023-10-02).