pylint-dev/pylint v3.0.0 on GitHub

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 for the loop
iteration, which would produce a false unbalanced-dict-unpacking warning.
Closes #8156
Fix false positive for used-before-assignment when usage and assignment
are guarded by the same test in different statements.
Closes #8167
Adds asyncSetUp to the default defining-attr-methods list to silence
attribute-defined-outside-init warning when using
unittest.IsolatedAsyncioTestCase.
Refs #8403
logging-not-lazy is not longer emitted for explicitly concatenated string arguments.
Closes #8410
Fix false positive for isinstance-second-argument-not-valid-type when union types contains None.
Closes #8424
invalid-name now allows for integers in typealias names:
- now valid: Good2Name, GoodName2.
- still invalid: _1BadName.
Closes #8485
No longer consider Union as type annotation as type alias for naming checks.
Closes #8487
unnecessary-lambda no longer warns on lambdas which use its parameters in
their body (other than the final arguments), e.g.
lambda foo: (bar if foo else baz)(foo).
Closes #8496
Fixed unused-import so that it observes the dummy-variables-rgx option.
Closes #8500
Union typed variables without assignment are no longer treated as
TypeAlias.
Closes #8540
Allow parenthesized implicitly concatenated strings when check-str-concat-over-line-jumps is enabled.
Closes #8552.
Fix false positive for positional-only-arguments-expected when a function contains both a positional-only parameter that has a default value, and **kwargs.
Closes #8555
Fix false positive for keyword-arg-before-vararg when a positional-only parameter with a default value precedes *args.
Closes #8570
Fix false positive for arguments-differ when overriding __init_subclass__.
Closes #8919
Fix a false positive for no-value-for-parameter when a staticmethod is called in a class body.
Closes #9036

False Negatives Fixed

Emit used-before-assignment when calling module-level functions before definition.
Closes #1144
Apply infer_kwarg_from_call() to more checks
These mostly solve false negatives for various checks,
save for one false positive for use-maxsplit-arg.
Closes #7761
TypeAlias variables defined in functions are now checked for invalid-name errors.
Closes #8536
Fix false negative for no-value-for-parameter when a function, whose signature contains both a positional-only parameter name and also *kwargs, is called with a keyword-argument for name.
Closes #8559
Fix a false negative for too-many-arguments by considering positional-only and keyword-only parameters.
Closes #8667
Emit assignment-from-no-return for calls to builtin methods like dict.update().
Calls to list.sort() now raise assignment-from-no-return
rather than assignment-from-none for consistency.
Closes #8714
Closes #8810
consider-using-augmented-assign is now applied to dicts and lists as well.
Closes #8959

Other Bug Fixes

Support duplicate-code message when parallelizing with --jobs.
Closes #374
Support cyclic-import message when parallelizing with --jobs.
Closes #4171
--jobs can now be used with --load-plugins.
This had regressed in astroid 2.5.0.
Closes #4874
docparams extension considers type comments as type documentation.
Closes #6287
When parsing comma-separated lists of regular expressions in the config, ignore
commas that are inside braces since those indicate quantifiers, not delineation
between expressions.
Closes #7229
The ignored-modules option will now be correctly taken into account for no-name-in-module.
Closes #7578
sys.argv is now always correctly considered as impossible to infer (instead of
using the actual values given to pylint).
Closes #7710
Avoid duplicative warnings for unqualified exception names in the overgeneral-exceptions
setting when running with --jobs.
Closes #7774
Don't show class fields more than once in Pyreverse diagrams.
Closes #8189
Fix used-before-assignment false negative when TYPE_CHECKING imports
are used in multiple scopes.
Closes #8198
--clear-cache-post-run now also clears LRU caches for pylint utilities
holding references to AST nodes.
Closes #8361
Fix a crash when TYPE_CHECKING is used without importing it.
Closes #8434
Fix a used-before-assignment false positive when imports
are made under the TYPE_CHECKING else if branch.
Closes #8437
Fix a regression of preferred-modules where a partial match was used instead of the required full match.
Closes #8453
Fix a crash in pyreverse when "/" characters are used in the output filename e.g pyreverse -o png -p name/ path/to/project.
Closes #8504
Don't show arrows more than once in Pyreverse diagrams.
Closes #8522
Improve output of consider-using-generator message for min() calls with default keyword.
Closes #8563
Fixed a crash when generating a configuration file: tomlkit.exceptions.TOMLKitError: Can't add a table to a dotted key
caused by tomlkit v0.11.8.
Closes #8632
Fix a line break error in Pyreverse dot output.
Closes #8671
Fix a false positive for method-hidden when using cached_property decorator.
Closes #8753
Dunder methods defined in lambda do not trigger unnecessary-dunder-call anymore, if they cannot be replaced by the non-dunder call.
Closes #8769
Don't show duplicate type annotations in Pyreverse diagrams.
Closes #8888
Fixing inconsistent hashing issue in BaseChecker causing some reports not being exported.
Closes #9001
Don't add Optional to | annotations with None in Pyreverse diagrams.
Closes #9014
Pyreverse doesn't show multiple class association arrows anymore, but only the strongest one.
Refs #9045
Prevented data loss in the linter stats for messages relating
to the linter itself (e.g. unknown-option-value), fixing
problems with score, fail-on, etc.
Closes #9059
Fix crash in refactoring checker when unary operand used with variable in for loop.
Closes #9074

Other Changes

Pylint now exposes its type annotations.
Closes #5488 and #2079
Search for pyproject.toml recursively in parent directories up to a project or file system root.
Refs #7163, Closes #3289
All code related to the optparse config parsing has been removed.
Refs #8405
Pylint now supports python 3.12.
Refs #8718
Add a CITATION.cff file to the root of the repository containing the necessary metadata to cite Pylint.
Closes #8760
Renamed the "unneeded-not" error into "unnecessary_negation" to be clearer.
Closes #8789

Internal Changes

get_message_definition was removed from the base checker API. You can access
message definitions through the MessageStore.
Refs #8401
Everything related to the __implements__ construct was removed. It was based on PEP245
that was proposed in 2001 and rejected in 2006.
All the classes inheriting Interface in pylint.interfaces were removed.
Checker should only inherit BaseChecker or any of the other checker types
from pylint.checkers. Reporter should only inherit BaseReporter.
Refs #8404
modname and msg_store are now required to be given in FileState.
collect_block_lines has also been removed. Pylinter.current_name
cannot be null anymore.
Refs #8407
Reporter.set_output was removed in favor of reporter.out = stream.
Refs #8408
A number of old utility functions and classes have been removed:
MapReduceMixin: To make a checker reduce map data simply implement
get_map_data and reduce_map_data.
is_inside_lambda: Use utils.get_node_first_ancestor_of_type(x, nodes.Lambda)
check_messages: Use utils.only_required_for_messages
is_class_subscriptable_pep585_with_postponed_evaluation_enabled: Use
is_postponed_evaluation_enabled(node) and is_node_in_type_annotation_context(node)
get_python_path: assumption that there's always an init.py is not true since
python 3.3 and is causing problems, particularly with PEP 420. Use discover_package_path
and pass source root(s).
fix_import_path: Use augmented_sys_path and pass additional sys.path
entries as an argument obtained from discover_package_path.
get_global_option: Use checker.linter.config to get all global options.
Related private objects have been removed as well.
Refs #8409
colorize_ansi now only accepts a MessageStyle object.
Refs #8412
Following a deprecation period, Pylinter.check now only works with sequences of strings, not strings.
Refs #8463
Following a deprecation period, ColorizedTextReporter only accepts ColorMappingDict.
Refs #8464
Following a deprecation period, MessageTest's end_line and end_col_offset
must be accurate in functional tests (for python 3.8 or above on cpython, and for
python 3.9 or superior on pypy).
Refs #8466
Following a deprecation period, the do_exit argument of the Run class (and of the _Run
class in testutils) were removed.
Refs #8472
Following a deprecation period, the py_version argument of the
MessageDefinition.may_be_emitted function is now required. The most likely solution
is to use 'linter.config.py_version' if you need to keep using this
function, or to use 'MessageDefinition.is_message_enabled' instead.
Refs #8473
Following a deprecation period, the OutputLine class now requires
the right number of argument all the time. The functional output can be
regenerated automatically to achieve that easily.
Refs #8474
Following a deprecation period, is_typing_guard, is_node_in_typing_guarded_import_block and
is_node_in_guarded_import_block from pylint.utils were removed: use a combination of
is_sys_guard and in_type_checking_block instead.
Refs #8475
Following a deprecation period, the location argument of the
Message class must now be a MessageLocationTuple.
Refs #8477
Following a deprecation period, the check_single_file function of the
Pylinter is replaced by Pylinter.check_single_file_item.
Refs #8478

Performance Improvements

pylint runs (at least) ~5% faster after improvements to astroid
that make better use of the inference cache.
Refs pylint-dev/astroid#529
- Optimize is_trailing_comma().
- Cache class_is_abstract().
Refs #1954
Exit immediately if all messages are disabled.
Closes #8715