pylint-dev/pylint v4.0.6

on GitHub

What's new in Pylint 4.0.6?

Release date: 2026-06-14

False Positives Fixed

• implicit-str-concat is no longer emitted for an implicit concatenation of
  a raw string with a non-raw one (e.g. r"\d" "\n"). Such literals cannot be
  merged into a single string, so the concatenation is intentional rather than a
  forgotten comma.

  Closes #6663

• Fix a false positive for invalid-name (C0103) where the default
  typevar-rgx rejected TypeVar names containing digits, such as
  Ec2T.

  Closes #8499

• Fix a false positive for too-many-arguments in (non-static) methods and classmethods.

  Closes #8675

• Fix a false positive for no-member when a value is inferred to several
  possible types and at least one of them defines a dynamic __getattr__.

  Closes #9833

• Fix a false positive for function-redefined (E0102) when reusing names that
  match dummy-variables-rgx (such as _), which is common for
  pytest-bdd step definitions. This restores the behavior from before pylint
  4.0.0; as a consequence the false negative fixed in #9894 is reintroduced for
  functions whose name matches dummy-variables-rgx.

  Closes #10665

• Fix undefined-variable false positive when a name used as a metaclass
  argument in a nested class is referenced again later in the module.

  Closes #10823

• Fix a false positive for unused-variable where global variables matching
  dummy-variables-rgx were still reported as unused when
  allow-global-unused-variables was disabled.

  Closes #10890

• Fix a false positive for bad-dunder-name when there is a user-defined __suppress_context__ attribute on exception subclasses.

  Closes #10960

• Fix used-before-assignment false positive for names bound by from X import * in every branch of an if/elif/else chain.

  Refs #10980

• Check for metaclass call signature when evaluating arguments of a class call.

  Closes #11032

• Fix false positive method-hidden when cached_property is imported directly with from functools import cached_property.

  Refs #11037

Other Bug Fixes

• Fix the suggestion of unnecessary-comprehension for a dict comprehension
  that iterates a dict directly, e.g. {a: b for a, b in d}. Iterating a dict
  yields its keys, so the suggestion is now dict(d.keys()) instead of the
  incorrect dict(d), which would simply copy d.

  Closes #8256

• Fix a crash in consider-using-enumerate when the for loop target is an attribute (e.g. for self.idx in range(len(x))) rather than a simple variable name.

  Closes #10099

• Fix crash when checking attribute-defined-outside-init on classes that inherit from a base class pylint cannot fully analyze.

  Closes #10892

• Fix add_message silently overwriting an explicit col_offset=0 (or any other zero-valued line/end_lineno/end_col_offset) with the AST node's value. The internal _add_one_message helper used a falsey check (if not col_offset:) to detect an omitted argument, which incorrectly treated a legitimate 0 the same as None. It now uses an identity check against None.

  Refs #11020

• Fix a crash in the name checker when a non-constant value is passed as the covariant or contravariant argument of a TypeVar.

  Closes #11022

• Fix a crash in the variable checker when a name resolves to a dataclass-synthesized __init__, which has no line number.

  Closes #11023

• Fix a crash in the variables checker when NotImplemented is used as the test of an if statement, which raised a TypeError in a boolean context on Python 3.14.

  Closes #11025

• Avoided a crash from the implicit booleaness checker for len() calls without arguments.

  Closes #11028

• Fix a crash in the variables checker when a class declares a metaclass whose
  attribute-access chain does not bottom out at a name (e.g.
  class C(metaclass=None._)).
  Originally reported as pylint-dev/astroid#3066.

  Refs #11031

• Fix a crash in the name checker when a chained assignment of a TypeAlias
  value has a non-name target such as a Subscript (for example
  a[0] = b = TypeAlias).

  Closes #11056

• Fix a crash in the deprecated checker when __import__ is called with a
  non-string constant argument (for example __import__(1)).

  Closes #11059

• Avoid crashing when enum member inference fails while checking enum subclasses.

  Closes #11069

• Prevent a crash in unexpected-keyword-arg analysis when
  infer_call_result() raises InferenceError while inspecting
  decorator return signatures.

  Closes #11070

• Fix a crash in the typecheck checker when a class uses a non-class object
  (for example a function) as its metaclass= argument.

  Closes #11071

• Allow digits in ParamSpec and TypeVarTuple names for invalid-name check.

  The default paramspec-rgx and typevartuple-rgx patterns rejected names
  containing digits (e.g. Ec2P, S3Ts), emitting a false invalid-name
  (C0103). Allow digits in the lowercase segments, consistent with the
  typevar and typealias patterns.

  Closes #11090

Performance Improvements

• The duplicate-code checker no longer runs when its message (R0801) is disabled, even if reports=yes is set. Previously, the checker's report (RP0801) would cause the expensive similarity computation to run regardless.

  Closes #3443