From 80510ae02eb0318f5ff7463b2ab159161608bb8a Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Tue, 30 Sep 2025 00:18:13 +0200
Subject: [PATCH 1/8] Add improve-conditionals check in the CodeStyle extension

---
 .../messages/i/improve-conditionals/bad.py    |  4 +
 .../messages/i/improve-conditionals/good.py   |  3 +
 .../messages/i/improve-conditionals/pylintrc  |  2 +
 doc/user_guide/checkers/extensions.rst        |  2 +
 doc/user_guide/messages/messages_overview.rst |  1 +
 doc/whatsnew/fragments/10600.new_check        |  3 +
 pylint/extensions/code_style.py               | 81 ++++++++++++++++++-
 .../ext/code_style/cs_improve_conditionals.py | 26 ++++++
 .../ext/code_style/cs_improve_conditionals.rc |  3 +
 .../code_style/cs_improve_conditionals.txt    |  6 ++
 10 files changed, 130 insertions(+), 1 deletion(-)
 create mode 100644 doc/data/messages/i/improve-conditionals/bad.py
 create mode 100644 doc/data/messages/i/improve-conditionals/good.py
 create mode 100644 doc/data/messages/i/improve-conditionals/pylintrc
 create mode 100644 doc/whatsnew/fragments/10600.new_check
 create mode 100644 tests/functional/ext/code_style/cs_improve_conditionals.py
 create mode 100644 tests/functional/ext/code_style/cs_improve_conditionals.rc
 create mode 100644 tests/functional/ext/code_style/cs_improve_conditionals.txt

diff --git a/doc/data/messages/i/improve-conditionals/bad.py b/doc/data/messages/i/improve-conditionals/bad.py
new file mode 100644
index 0000000000..85d0473b29
--- /dev/null
+++ b/doc/data/messages/i/improve-conditionals/bad.py
@@ -0,0 +1,4 @@
+def func(expr, node_cls):
+    # +1:[improve-conditionals]
+    if not isinstance(expr, node_cls) or expr.attrname != "__init__":
+        ...
diff --git a/doc/data/messages/i/improve-conditionals/good.py b/doc/data/messages/i/improve-conditionals/good.py
new file mode 100644
index 0000000000..55e3eedf40
--- /dev/null
+++ b/doc/data/messages/i/improve-conditionals/good.py
@@ -0,0 +1,3 @@
+def func(expr, node_cls):
+    if not (isinstance(expr, node_cls) and expr.attrname == "__init__"):
+        ...
diff --git a/doc/data/messages/i/improve-conditionals/pylintrc b/doc/data/messages/i/improve-conditionals/pylintrc
new file mode 100644
index 0000000000..8663ab085d
--- /dev/null
+++ b/doc/data/messages/i/improve-conditionals/pylintrc
@@ -0,0 +1,2 @@
+[MAIN]
+load-plugins=pylint.extensions.code_style
diff --git a/doc/user_guide/checkers/extensions.rst b/doc/user_guide/checkers/extensions.rst
index c9dead7ca3..e289cc7bcd 100644
--- a/doc/user_guide/checkers/extensions.rst
+++ b/doc/user_guide/checkers/extensions.rst
@@ -92,6 +92,8 @@ Code Style checker Messages
   Using math.inf or math.nan permits to benefit from typing and it is up to 4
   times faster than a float call (after the initial import of math). This check
   also catches typos in float calls as a side effect.
+:improve-conditionals (R6107): *Rewrite conditional expression to '%s'*
+  Rewrite negated if expressions to improve readability.
 
 
 .. _pylint.extensions.comparison_placement:
diff --git a/doc/user_guide/messages/messages_overview.rst b/doc/user_guide/messages/messages_overview.rst
index 87685835bb..dc97341598 100644
--- a/doc/user_guide/messages/messages_overview.rst
+++ b/doc/user_guide/messages/messages_overview.rst
@@ -516,6 +516,7 @@ All messages in the refactor category:
    refactor/duplicate-code
    refactor/else-if-used
    refactor/empty-comment
+   refactor/improve-conditionals
    refactor/inconsistent-return-statements
    refactor/literal-comparison
    refactor/magic-value-comparison
diff --git a/doc/whatsnew/fragments/10600.new_check b/doc/whatsnew/fragments/10600.new_check
new file mode 100644
index 0000000000..e641880445
--- /dev/null
+++ b/doc/whatsnew/fragments/10600.new_check
@@ -0,0 +1,3 @@
+Add :ref:`improve-conditionals` check to the Code Style extension.
+
+Refs #10600
diff --git a/pylint/extensions/code_style.py b/pylint/extensions/code_style.py
index d8ea869cb9..c77c908a6c 100644
--- a/pylint/extensions/code_style.py
+++ b/pylint/extensions/code_style.py
@@ -5,13 +5,14 @@
 from __future__ import annotations
 
 import difflib
+from copy import copy
 from typing import TYPE_CHECKING, TypeGuard, cast
 
 from astroid import nodes
 
 from pylint.checkers import BaseChecker, utils
 from pylint.checkers.utils import only_required_for_messages, safe_infer
-from pylint.interfaces import INFERENCE
+from pylint.interfaces import HIGH, INFERENCE
 
 if TYPE_CHECKING:
     from pylint.lint import PyLinter
@@ -82,6 +83,14 @@ class CodeStyleChecker(BaseChecker):
             "to 4 times faster than a float call (after the initial import of math). "
             "This check also catches typos in float calls as a side effect.",
         ),
+        "R6107": (
+            "Rewrite conditional expression to '%s'",
+            "improve-conditionals",
+            "Rewrite negated if expressions to improve readability.",
+            {
+                # "default_enabled": False,
+            },
+        ),
     }
     options = (
         (
@@ -356,6 +365,76 @@ def visit_assign(self, node: nodes.Assign) -> None:
                 confidence=INFERENCE,
             )
 
+    @staticmethod
+    def _can_be_inverted(node: nodes.NodeNG) -> bool:
+        match node:
+            case nodes.UnaryOp(op="not"):
+                return True
+            case nodes.Compare(
+                ops=[("!=" | "not in", _)]
+                | [("<" | "<=" | ">" | ">=", nodes.Const(value=int()))]
+            ):
+                return True
+        return False
+
+    @staticmethod
+    def _invert_node(node: nodes.NodeNG) -> nodes.NodeNG:
+        match node:
+            case nodes.UnaryOp(op="not"):
+                new_node = copy(node.operand)
+                new_node.parent = node
+                return new_node
+            case nodes.Compare(left=left, ops=[(op, n)]):
+                new_node = copy(node)
+                match op:
+                    case "!=":
+                        new_op = "=="
+                    case "not in":
+                        new_op = "in"
+                    case "<":
+                        new_op = ">="
+                    case "<=":
+                        new_op = ">"
+                    case ">":
+                        new_op = "<="
+                    case ">=":
+                        new_op = "<"
+                    case _:  # pragma: no cover
+                        raise AssertionError
+                new_node.postinit(left=left, ops=[(new_op, n)])
+                return new_node
+            case _:  # pragma: no cover
+                raise AssertionError
+
+    @only_required_for_messages("improve-conditionals")
+    def visit_boolop(self, node: nodes.BoolOp) -> None:
+        if node.op == "or" and all(self._can_be_inverted(val) for val in node.values):
+            new_boolop = copy(node)
+            new_boolop.op = "and"
+            new_boolop.postinit([self._invert_node(val) for val in node.values])
+
+            if isinstance(node.parent, nodes.UnaryOp) and node.parent.op == "not":
+                target_node = node.parent
+                new_node = new_boolop
+            else:
+                target_node = node
+                new_node = nodes.UnaryOp(
+                    op="not",
+                    lineno=0,
+                    col_offset=0,
+                    end_lineno=None,
+                    end_col_offset=None,
+                    parent=node.parent,
+                )
+                new_node.postinit(operand=new_boolop)
+
+            self.add_message(
+                "improve-conditionals",
+                node=target_node,
+                args=(new_node.as_string(),),
+                confidence=HIGH,
+            )
+
 
 def register(linter: PyLinter) -> None:
     linter.register_checker(CodeStyleChecker(linter))
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.py b/tests/functional/ext/code_style/cs_improve_conditionals.py
new file mode 100644
index 0000000000..9fee26a4fe
--- /dev/null
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.py
@@ -0,0 +1,26 @@
+# pylint: disable=missing-docstring
+
+def f1(expr, node_cls, x, y, z):
+    if isinstance(expr, node_cls) and expr.attrname == "__init__":
+        ...
+    elif isinstance(expr, node_cls) or expr.attrname == "__init__":
+        ...
+    elif not isinstance(expr, node_cls) and expr.attrname == "__init__":
+        ...
+    elif not isinstance(expr, node_cls) and expr.attrname != "__init__":
+        ...
+    elif not isinstance(expr, node_cls) or expr.attrname == "__init__":
+        ...
+
+    if not isinstance(expr, node_cls) or expr.attrname != "__init__":  # [improve-conditionals]
+        ...
+    elif x > 0 or y >= 1:  # [improve-conditionals]
+        ...
+    elif x < 0 or y <= 1:  # [improve-conditionals]
+        ...
+    elif not x or y not in z:  # [improve-conditionals]
+        ...
+    elif not (not x or not y):  # [improve-conditionals]
+        ...
+    elif x and (not y or not z):  # [improve-conditionals]
+        ...
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.rc b/tests/functional/ext/code_style/cs_improve_conditionals.rc
new file mode 100644
index 0000000000..74d18e403f
--- /dev/null
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.rc
@@ -0,0 +1,3 @@
+[MAIN]
+load-plugins=pylint.extensions.code_style
+enable=improve-conditionals
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.txt b/tests/functional/ext/code_style/cs_improve_conditionals.txt
new file mode 100644
index 0000000000..c2e00086e3
--- /dev/null
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.txt
@@ -0,0 +1,6 @@
+improve-conditionals:15:7:15:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
+improve-conditionals:17:9:17:24:f1:Rewrite conditional expression to 'not (x <= 0 and y < 1)':HIGH
+improve-conditionals:19:9:19:24:f1:Rewrite conditional expression to 'not (x >= 0 and y > 1)':HIGH
+improve-conditionals:21:9:21:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
+improve-conditionals:23:9:23:29:f1:Rewrite conditional expression to 'x and y':HIGH
+improve-conditionals:25:16:25:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH

From 2b8af0e2cfc3263142f33316fe34ea1357ac1fd6 Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Wed, 1 Oct 2025 21:12:55 +0200
Subject: [PATCH 2/8] Don't emit message for 'x < 0 or x > 100'

---
 pylint/extensions/code_style.py               | 38 +++++++++++++------
 .../ext/code_style/cs_improve_conditionals.py |  9 +++--
 .../code_style/cs_improve_conditionals.txt    | 10 ++---
 3 files changed, 37 insertions(+), 20 deletions(-)

diff --git a/pylint/extensions/code_style.py b/pylint/extensions/code_style.py
index c77c908a6c..0f55b1cafd 100644
--- a/pylint/extensions/code_style.py
+++ b/pylint/extensions/code_style.py
@@ -6,6 +6,7 @@
 
 import difflib
 from copy import copy
+from enum import IntFlag, auto
 from typing import TYPE_CHECKING, TypeGuard, cast
 
 from astroid import nodes
@@ -18,6 +19,12 @@
     from pylint.lint import PyLinter
 
 
+class InvertibleValues(IntFlag):
+    NO = 0
+    YES = auto()
+    EXPLICIT_NEGATION = auto()
+
+
 class CodeStyleChecker(BaseChecker):
     """Checkers that can improve code consistency.
 
@@ -366,16 +373,21 @@ def visit_assign(self, node: nodes.Assign) -> None:
             )
 
     @staticmethod
-    def _can_be_inverted(node: nodes.NodeNG) -> bool:
-        match node:
-            case nodes.UnaryOp(op="not"):
-                return True
-            case nodes.Compare(
-                ops=[("!=" | "not in", _)]
-                | [("<" | "<=" | ">" | ">=", nodes.Const(value=int()))]
-            ):
-                return True
-        return False
+    def _can_be_inverted(values: list[nodes.NodeNG]) -> InvertibleValues:
+        invertible = InvertibleValues.NO
+        for node in values:
+            match node:
+                case nodes.UnaryOp(op="not") | nodes.Compare(
+                    ops=[("!=" | "not in", _)]
+                ):
+                    invertible |= InvertibleValues.EXPLICIT_NEGATION
+                case nodes.Compare(
+                    ops=[("<" | "<=" | ">" | ">=", nodes.Const(value=int()))]
+                ):
+                    invertible |= InvertibleValues.YES
+                case _:
+                    return InvertibleValues.NO
+        return invertible
 
     @staticmethod
     def _invert_node(node: nodes.NodeNG) -> nodes.NodeNG:
@@ -408,7 +420,11 @@ def _invert_node(node: nodes.NodeNG) -> nodes.NodeNG:
 
     @only_required_for_messages("improve-conditionals")
     def visit_boolop(self, node: nodes.BoolOp) -> None:
-        if node.op == "or" and all(self._can_be_inverted(val) for val in node.values):
+        if (
+            node.op == "or"
+            and (invertible := self._can_be_inverted(node.values))
+            and invertible & InvertibleValues.EXPLICIT_NEGATION
+        ):
             new_boolop = copy(node)
             new_boolop.op = "and"
             new_boolop.postinit([self._invert_node(val) for val in node.values])
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.py b/tests/functional/ext/code_style/cs_improve_conditionals.py
index 9fee26a4fe..42ad04249e 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.py
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.py
@@ -12,11 +12,14 @@ def f1(expr, node_cls, x, y, z):
     elif not isinstance(expr, node_cls) or expr.attrname == "__init__":
         ...
 
-    if not isinstance(expr, node_cls) or expr.attrname != "__init__":  # [improve-conditionals]
+    if x < 0 or x > 100:
+        ...
+    elif x > 0 or y >= 1:
         ...
-    elif x > 0 or y >= 1:  # [improve-conditionals]
+    elif x < 0 or y <= 1:
         ...
-    elif x < 0 or y <= 1:  # [improve-conditionals]
+
+    if not isinstance(expr, node_cls) or expr.attrname != "__init__":  # [improve-conditionals]
         ...
     elif not x or y not in z:  # [improve-conditionals]
         ...
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.txt b/tests/functional/ext/code_style/cs_improve_conditionals.txt
index c2e00086e3..e19ff77f3f 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.txt
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.txt
@@ -1,6 +1,4 @@
-improve-conditionals:15:7:15:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
-improve-conditionals:17:9:17:24:f1:Rewrite conditional expression to 'not (x <= 0 and y < 1)':HIGH
-improve-conditionals:19:9:19:24:f1:Rewrite conditional expression to 'not (x >= 0 and y > 1)':HIGH
-improve-conditionals:21:9:21:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
-improve-conditionals:23:9:23:29:f1:Rewrite conditional expression to 'x and y':HIGH
-improve-conditionals:25:16:25:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH
+improve-conditionals:22:7:22:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
+improve-conditionals:24:9:24:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
+improve-conditionals:26:9:26:29:f1:Rewrite conditional expression to 'x and y':HIGH
+improve-conditionals:28:16:28:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH

From 6a40da3839125ae3be0cdd84e380e3ef3f8943a6 Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Wed, 1 Oct 2025 21:17:15 +0200
Subject: [PATCH 3/8] Code review

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>
---
 doc/data/messages/i/improve-conditionals/bad.py  | 9 +++++----
 doc/data/messages/i/improve-conditionals/good.py | 6 +++---
 doc/user_guide/checkers/extensions.rst           | 4 +++-
 doc/user_guide/configuration/all-options.rst     | 2 +-
 pylint/extensions/code_style.py                  | 6 ++++--
 5 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/doc/data/messages/i/improve-conditionals/bad.py b/doc/data/messages/i/improve-conditionals/bad.py
index 85d0473b29..93bc0dd739 100644
--- a/doc/data/messages/i/improve-conditionals/bad.py
+++ b/doc/data/messages/i/improve-conditionals/bad.py
@@ -1,4 +1,5 @@
-def func(expr, node_cls):
-    # +1:[improve-conditionals]
-    if not isinstance(expr, node_cls) or expr.attrname != "__init__":
-        ...
+def is_penguin(animal):
+    # Penguins are the only flightless, kneeless sea birds
+    return animal.is_seabird() and (
+        not animal.can_fly() or not animal.has_visible_knee()  # [improve-conditionals]
+    )
diff --git a/doc/data/messages/i/improve-conditionals/good.py b/doc/data/messages/i/improve-conditionals/good.py
index 55e3eedf40..4fa3a1d8ae 100644
--- a/doc/data/messages/i/improve-conditionals/good.py
+++ b/doc/data/messages/i/improve-conditionals/good.py
@@ -1,3 +1,3 @@
-def func(expr, node_cls):
-    if not (isinstance(expr, node_cls) and expr.attrname == "__init__"):
-        ...
+def is_penguin(animal):
+    # Penguins are the only flightless, kneeless sea birds
+    return animal.is_seabird() and not (animal.can_fly() or animal.has_visible_knee())
diff --git a/doc/user_guide/checkers/extensions.rst b/doc/user_guide/checkers/extensions.rst
index e289cc7bcd..96c31f1619 100644
--- a/doc/user_guide/checkers/extensions.rst
+++ b/doc/user_guide/checkers/extensions.rst
@@ -93,7 +93,9 @@ Code Style checker Messages
   times faster than a float call (after the initial import of math). This check
   also catches typos in float calls as a side effect.
 :improve-conditionals (R6107): *Rewrite conditional expression to '%s'*
-  Rewrite negated if expressions to improve readability.
+  Rewrite negated if expressions to improve readability. This style is simpler
+  and also permits converting long if/elif chains to match case with more ease.
+  Disabled by default!
 
 
 .. _pylint.extensions.comparison_placement:
diff --git a/doc/user_guide/configuration/all-options.rst b/doc/user_guide/configuration/all-options.rst
index 309714a0de..e912a4f77b 100644
--- a/doc/user_guide/configuration/all-options.rst
+++ b/doc/user_guide/configuration/all-options.rst
@@ -233,7 +233,7 @@ Standard Checkers
 
    confidence = ["HIGH", "CONTROL_FLOW", "INFERENCE", "INFERENCE_FAILURE", "UNDEFINED"]
 
-   disable = ["bad-inline-option", "consider-using-augmented-assign", "deprecated-pragma", "file-ignored", "locally-disabled", "prefer-typing-namedtuple", "raw-checker-failed", "suppressed-message", "use-implicit-booleaness-not-comparison-to-string", "use-implicit-booleaness-not-comparison-to-zero", "use-symbolic-message-instead", "useless-suppression"]
+   disable = ["bad-inline-option", "consider-using-augmented-assign", "deprecated-pragma", "file-ignored", "improve-conditionals", "locally-disabled", "prefer-typing-namedtuple", "raw-checker-failed", "suppressed-message", "use-implicit-booleaness-not-comparison-to-string", "use-implicit-booleaness-not-comparison-to-zero", "use-symbolic-message-instead", "useless-suppression"]
 
    enable = []
 
diff --git a/pylint/extensions/code_style.py b/pylint/extensions/code_style.py
index 0f55b1cafd..0aa0a726eb 100644
--- a/pylint/extensions/code_style.py
+++ b/pylint/extensions/code_style.py
@@ -93,9 +93,11 @@ class CodeStyleChecker(BaseChecker):
         "R6107": (
             "Rewrite conditional expression to '%s'",
             "improve-conditionals",
-            "Rewrite negated if expressions to improve readability.",
+            "Rewrite negated if expressions to improve readability. This style is simpler "
+            "and also permits converting long if/elif chains to match case with more ease.\n"
+            "Disabled by default!",
             {
-                # "default_enabled": False,
+                "default_enabled": False,
             },
         ),
     }

From 1b7090c87e5eb5db64e6d654aada7aa7ed95b0c7 Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Thu, 2 Oct 2025 20:55:28 +0200
Subject: [PATCH 4/8] Enable improve-conditionals check for pylint itself

---
 pylintrc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pylintrc b/pylintrc
index fe653a092c..f824db6466 100644
--- a/pylintrc
+++ b/pylintrc
@@ -81,6 +81,7 @@ clear-cache-post-run=no
 # multiple time (only on the command line, not in the configuration file where
 # it should appear only once). See also the "--disable" option for examples.
 enable=
+    improve-conditionals,
     use-symbolic-message-instead,
     useless-suppression,
 

From 91cbba1ee86825966b2772795291fdd845fe21fd Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Mon, 13 Oct 2025 12:34:19 +0200
Subject: [PATCH 5/8] Deal with 'is not' but exclude 'is not None'

---
 pylint/extensions/code_style.py                          | 8 ++++++--
 .../functional/ext/code_style/cs_improve_conditionals.py | 9 ++++++++-
 .../ext/code_style/cs_improve_conditionals.txt           | 9 +++++----
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/pylint/extensions/code_style.py b/pylint/extensions/code_style.py
index 0aa0a726eb..a280e9673b 100644
--- a/pylint/extensions/code_style.py
+++ b/pylint/extensions/code_style.py
@@ -379,8 +379,10 @@ def _can_be_inverted(values: list[nodes.NodeNG]) -> InvertibleValues:
         invertible = InvertibleValues.NO
         for node in values:
             match node:
-                case nodes.UnaryOp(op="not") | nodes.Compare(
-                    ops=[("!=" | "not in", _)]
+                case nodes.UnaryOp(op="not"):
+                    invertible |= InvertibleValues.EXPLICIT_NEGATION
+                case nodes.Compare(ops=[("!=" | "not in" | "is not" as op, n)]) if not (
+                    op == "is not" and isinstance(n, nodes.Const) and n.value is None
                 ):
                     invertible |= InvertibleValues.EXPLICIT_NEGATION
                 case nodes.Compare(
@@ -405,6 +407,8 @@ def _invert_node(node: nodes.NodeNG) -> nodes.NodeNG:
                         new_op = "=="
                     case "not in":
                         new_op = "in"
+                    case "is not":
+                        new_op = "is"
                     case "<":
                         new_op = ">="
                     case "<=":
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.py b/tests/functional/ext/code_style/cs_improve_conditionals.py
index 42ad04249e..383c6dc00d 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.py
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.py
@@ -1,4 +1,4 @@
-# pylint: disable=missing-docstring
+# pylint: disable=missing-docstring,too-many-branches
 
 def f1(expr, node_cls, x, y, z):
     if isinstance(expr, node_cls) and expr.attrname == "__init__":
@@ -19,10 +19,17 @@ def f1(expr, node_cls, x, y, z):
     elif x < 0 or y <= 1:
         ...
 
+    if x is not None or y is not None:
+        ...
+    elif not isinstance(expr, node_cls) or x is not None:
+        ...
+
     if not isinstance(expr, node_cls) or expr.attrname != "__init__":  # [improve-conditionals]
         ...
     elif not x or y not in z:  # [improve-conditionals]
         ...
+    elif not x or y is not z:  # [improve-conditionals]
+        ...
     elif not (not x or not y):  # [improve-conditionals]
         ...
     elif x and (not y or not z):  # [improve-conditionals]
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.txt b/tests/functional/ext/code_style/cs_improve_conditionals.txt
index e19ff77f3f..54440f751a 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.txt
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.txt
@@ -1,4 +1,5 @@
-improve-conditionals:22:7:22:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
-improve-conditionals:24:9:24:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
-improve-conditionals:26:9:26:29:f1:Rewrite conditional expression to 'x and y':HIGH
-improve-conditionals:28:16:28:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH
+improve-conditionals:27:7:27:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
+improve-conditionals:29:9:29:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
+improve-conditionals:31:9:31:28:f1:Rewrite conditional expression to 'not (x and y is z)':HIGH
+improve-conditionals:33:9:33:29:f1:Rewrite conditional expression to 'x and y':HIGH
+improve-conditionals:35:16:35:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH

From 094f05530cfa5f971890653f832547fbac87144b Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Mon, 13 Oct 2025 12:34:45 +0200
Subject: [PATCH 6/8] Increase test coverage

---
 tests/functional/ext/code_style/cs_improve_conditionals.py  | 4 ++++
 tests/functional/ext/code_style/cs_improve_conditionals.txt | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.py b/tests/functional/ext/code_style/cs_improve_conditionals.py
index 383c6dc00d..7c1c57195d 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.py
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.py
@@ -34,3 +34,7 @@ def f1(expr, node_cls, x, y, z):
         ...
     elif x and (not y or not z):  # [improve-conditionals]
         ...
+    elif not x or y < 0 or z <= 0:  # [improve-conditionals]
+        ...
+    elif not x or y > 0 or z >= 0:  # [improve-conditionals]
+        ...
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.txt b/tests/functional/ext/code_style/cs_improve_conditionals.txt
index 54440f751a..887f9b82ab 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.txt
+++ b/tests/functional/ext/code_style/cs_improve_conditionals.txt
@@ -3,3 +3,5 @@ improve-conditionals:29:9:29:28:f1:Rewrite conditional expression to 'not (x and
 improve-conditionals:31:9:31:28:f1:Rewrite conditional expression to 'not (x and y is z)':HIGH
 improve-conditionals:33:9:33:29:f1:Rewrite conditional expression to 'x and y':HIGH
 improve-conditionals:35:16:35:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH
+improve-conditionals:37:9:37:33:f1:Rewrite conditional expression to 'not (x and y >= 0 and z > 0)':HIGH
+improve-conditionals:39:9:39:33:f1:Rewrite conditional expression to 'not (x and y <= 0 and z < 0)':HIGH

From e94d54e2d9cafdc7bf07220bd3df50690f4d3980 Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Mon, 13 Oct 2025 12:54:35 +0200
Subject: [PATCH 7/8] Change name to 'consider-rewriting-conditional'

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>
---
 .../consider-rewriting-conditional}/bad.py        |  4 +++-
 .../consider-rewriting-conditional}/good.py       |  0
 .../consider-rewriting-conditional}/pylintrc      |  0
 doc/user_guide/checkers/extensions.rst            |  2 +-
 doc/user_guide/configuration/all-options.rst      |  2 +-
 doc/user_guide/messages/messages_overview.rst     |  2 +-
 doc/whatsnew/fragments/10600.new_check            |  5 ++++-
 pylint/extensions/code_style.py                   |  6 +++---
 pylintrc                                          |  2 +-
 ...ls.py => cs_consider_rewriting_conditional.py} | 15 ++++++++-------
 ...ls.rc => cs_consider_rewriting_conditional.rc} |  2 +-
 .../cs_consider_rewriting_conditional.txt         |  7 +++++++
 .../ext/code_style/cs_improve_conditionals.txt    |  7 -------
 13 files changed, 30 insertions(+), 24 deletions(-)
 rename doc/data/messages/{i/improve-conditionals => c/consider-rewriting-conditional}/bad.py (51%)
 rename doc/data/messages/{i/improve-conditionals => c/consider-rewriting-conditional}/good.py (100%)
 rename doc/data/messages/{i/improve-conditionals => c/consider-rewriting-conditional}/pylintrc (100%)
 rename tests/functional/ext/code_style/{cs_improve_conditionals.py => cs_consider_rewriting_conditional.py} (65%)
 rename tests/functional/ext/code_style/{cs_improve_conditionals.rc => cs_consider_rewriting_conditional.rc} (56%)
 create mode 100644 tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt
 delete mode 100644 tests/functional/ext/code_style/cs_improve_conditionals.txt

diff --git a/doc/data/messages/i/improve-conditionals/bad.py b/doc/data/messages/c/consider-rewriting-conditional/bad.py
similarity index 51%
rename from doc/data/messages/i/improve-conditionals/bad.py
rename to doc/data/messages/c/consider-rewriting-conditional/bad.py
index 93bc0dd739..e498b6cb7c 100644
--- a/doc/data/messages/i/improve-conditionals/bad.py
+++ b/doc/data/messages/c/consider-rewriting-conditional/bad.py
@@ -1,5 +1,7 @@
 def is_penguin(animal):
     # Penguins are the only flightless, kneeless sea birds
     return animal.is_seabird() and (
-        not animal.can_fly() or not animal.has_visible_knee()  # [improve-conditionals]
+        # +1: [consider-rewriting-conditional]
+        not animal.can_fly()
+        or not animal.has_visible_knee()
     )
diff --git a/doc/data/messages/i/improve-conditionals/good.py b/doc/data/messages/c/consider-rewriting-conditional/good.py
similarity index 100%
rename from doc/data/messages/i/improve-conditionals/good.py
rename to doc/data/messages/c/consider-rewriting-conditional/good.py
diff --git a/doc/data/messages/i/improve-conditionals/pylintrc b/doc/data/messages/c/consider-rewriting-conditional/pylintrc
similarity index 100%
rename from doc/data/messages/i/improve-conditionals/pylintrc
rename to doc/data/messages/c/consider-rewriting-conditional/pylintrc
diff --git a/doc/user_guide/checkers/extensions.rst b/doc/user_guide/checkers/extensions.rst
index 96c31f1619..14e5ae0107 100644
--- a/doc/user_guide/checkers/extensions.rst
+++ b/doc/user_guide/checkers/extensions.rst
@@ -92,7 +92,7 @@ Code Style checker Messages
   Using math.inf or math.nan permits to benefit from typing and it is up to 4
   times faster than a float call (after the initial import of math). This check
   also catches typos in float calls as a side effect.
-:improve-conditionals (R6107): *Rewrite conditional expression to '%s'*
+:consider-rewriting-conditional (R6107): *Rewrite conditional expression to '%s'*
   Rewrite negated if expressions to improve readability. This style is simpler
   and also permits converting long if/elif chains to match case with more ease.
   Disabled by default!
diff --git a/doc/user_guide/configuration/all-options.rst b/doc/user_guide/configuration/all-options.rst
index e912a4f77b..084388d6a2 100644
--- a/doc/user_guide/configuration/all-options.rst
+++ b/doc/user_guide/configuration/all-options.rst
@@ -233,7 +233,7 @@ Standard Checkers
 
    confidence = ["HIGH", "CONTROL_FLOW", "INFERENCE", "INFERENCE_FAILURE", "UNDEFINED"]
 
-   disable = ["bad-inline-option", "consider-using-augmented-assign", "deprecated-pragma", "file-ignored", "improve-conditionals", "locally-disabled", "prefer-typing-namedtuple", "raw-checker-failed", "suppressed-message", "use-implicit-booleaness-not-comparison-to-string", "use-implicit-booleaness-not-comparison-to-zero", "use-symbolic-message-instead", "useless-suppression"]
+   disable = ["bad-inline-option", "consider-rewriting-conditional", "consider-using-augmented-assign", "deprecated-pragma", "file-ignored", "locally-disabled", "prefer-typing-namedtuple", "raw-checker-failed", "suppressed-message", "use-implicit-booleaness-not-comparison-to-string", "use-implicit-booleaness-not-comparison-to-zero", "use-symbolic-message-instead", "useless-suppression"]
 
    enable = []
 
diff --git a/doc/user_guide/messages/messages_overview.rst b/doc/user_guide/messages/messages_overview.rst
index dc97341598..4112ca47a3 100644
--- a/doc/user_guide/messages/messages_overview.rst
+++ b/doc/user_guide/messages/messages_overview.rst
@@ -494,6 +494,7 @@ All messages in the refactor category:
    refactor/consider-math-not-float
    refactor/consider-merging-isinstance
    refactor/consider-refactoring-into-while-condition
+   refactor/consider-rewriting-conditional
    refactor/consider-swap-variables
    refactor/consider-using-alias
    refactor/consider-using-assignment-expr
@@ -516,7 +517,6 @@ All messages in the refactor category:
    refactor/duplicate-code
    refactor/else-if-used
    refactor/empty-comment
-   refactor/improve-conditionals
    refactor/inconsistent-return-statements
    refactor/literal-comparison
    refactor/magic-value-comparison
diff --git a/doc/whatsnew/fragments/10600.new_check b/doc/whatsnew/fragments/10600.new_check
index e641880445..135951842b 100644
--- a/doc/whatsnew/fragments/10600.new_check
+++ b/doc/whatsnew/fragments/10600.new_check
@@ -1,3 +1,6 @@
-Add :ref:`improve-conditionals` check to the Code Style extension.
+Add ``consider-rewriting-conditional`` check to the Code Style extension to suggest
+``not (x and y)`` instead of ``not x or not y`` in order to facilitate the detection
+of match case refactors. The code style extension must be enabled and
+``consider-rewriting-conditional`` itself needs to be explicitly enabled.
 
 Refs #10600
diff --git a/pylint/extensions/code_style.py b/pylint/extensions/code_style.py
index a280e9673b..e17c9358c0 100644
--- a/pylint/extensions/code_style.py
+++ b/pylint/extensions/code_style.py
@@ -92,7 +92,7 @@ class CodeStyleChecker(BaseChecker):
         ),
         "R6107": (
             "Rewrite conditional expression to '%s'",
-            "improve-conditionals",
+            "consider-rewriting-conditional",
             "Rewrite negated if expressions to improve readability. This style is simpler "
             "and also permits converting long if/elif chains to match case with more ease.\n"
             "Disabled by default!",
@@ -424,7 +424,7 @@ def _invert_node(node: nodes.NodeNG) -> nodes.NodeNG:
             case _:  # pragma: no cover
                 raise AssertionError
 
-    @only_required_for_messages("improve-conditionals")
+    @only_required_for_messages("consider-rewriting-conditional")
     def visit_boolop(self, node: nodes.BoolOp) -> None:
         if (
             node.op == "or"
@@ -451,7 +451,7 @@ def visit_boolop(self, node: nodes.BoolOp) -> None:
                 new_node.postinit(operand=new_boolop)
 
             self.add_message(
-                "improve-conditionals",
+                "consider-rewriting-conditional",
                 node=target_node,
                 args=(new_node.as_string(),),
                 confidence=HIGH,
diff --git a/pylintrc b/pylintrc
index f824db6466..43fba9fa4c 100644
--- a/pylintrc
+++ b/pylintrc
@@ -81,7 +81,7 @@ clear-cache-post-run=no
 # multiple time (only on the command line, not in the configuration file where
 # it should appear only once). See also the "--disable" option for examples.
 enable=
-    improve-conditionals,
+    consider-rewriting-conditional,
     use-symbolic-message-instead,
     useless-suppression,
 
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.py b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.py
similarity index 65%
rename from tests/functional/ext/code_style/cs_improve_conditionals.py
rename to tests/functional/ext/code_style/cs_consider_rewriting_conditional.py
index 7c1c57195d..3e72d62a4b 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.py
+++ b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.py
@@ -24,17 +24,18 @@ def f1(expr, node_cls, x, y, z):
     elif not isinstance(expr, node_cls) or x is not None:
         ...
 
-    if not isinstance(expr, node_cls) or expr.attrname != "__init__":  # [improve-conditionals]
+    # +1: [consider-rewriting-conditional]
+    if not isinstance(expr, node_cls) or expr.attrname != "__init__":
         ...
-    elif not x or y not in z:  # [improve-conditionals]
+    elif not x or y not in z:  # [consider-rewriting-conditional]
         ...
-    elif not x or y is not z:  # [improve-conditionals]
+    elif not x or y is not z:  # [consider-rewriting-conditional]
         ...
-    elif not (not x or not y):  # [improve-conditionals]
+    elif not (not x or not y):  # [consider-rewriting-conditional]
         ...
-    elif x and (not y or not z):  # [improve-conditionals]
+    elif x and (not y or not z):  # [consider-rewriting-conditional]
         ...
-    elif not x or y < 0 or z <= 0:  # [improve-conditionals]
+    elif not x or y < 0 or z <= 0:  # [consider-rewriting-conditional]
         ...
-    elif not x or y > 0 or z >= 0:  # [improve-conditionals]
+    elif not x or y > 0 or z >= 0:  # [consider-rewriting-conditional]
         ...
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.rc b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.rc
similarity index 56%
rename from tests/functional/ext/code_style/cs_improve_conditionals.rc
rename to tests/functional/ext/code_style/cs_consider_rewriting_conditional.rc
index 74d18e403f..794559fb63 100644
--- a/tests/functional/ext/code_style/cs_improve_conditionals.rc
+++ b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.rc
@@ -1,3 +1,3 @@
 [MAIN]
 load-plugins=pylint.extensions.code_style
-enable=improve-conditionals
+enable=consider-rewriting-conditional
diff --git a/tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt
new file mode 100644
index 0000000000..2ada42ac0d
--- /dev/null
+++ b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt
@@ -0,0 +1,7 @@
+consider-rewriting-conditional:28:7:28:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
+consider-rewriting-conditional:30:9:30:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
+consider-rewriting-conditional:32:9:32:28:f1:Rewrite conditional expression to 'not (x and y is z)':HIGH
+consider-rewriting-conditional:34:9:34:29:f1:Rewrite conditional expression to 'x and y':HIGH
+consider-rewriting-conditional:36:16:36:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH
+consider-rewriting-conditional:38:9:38:33:f1:Rewrite conditional expression to 'not (x and y >= 0 and z > 0)':HIGH
+consider-rewriting-conditional:40:9:40:33:f1:Rewrite conditional expression to 'not (x and y <= 0 and z < 0)':HIGH
diff --git a/tests/functional/ext/code_style/cs_improve_conditionals.txt b/tests/functional/ext/code_style/cs_improve_conditionals.txt
deleted file mode 100644
index 887f9b82ab..0000000000
--- a/tests/functional/ext/code_style/cs_improve_conditionals.txt
+++ /dev/null
@@ -1,7 +0,0 @@
-improve-conditionals:27:7:27:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
-improve-conditionals:29:9:29:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
-improve-conditionals:31:9:31:28:f1:Rewrite conditional expression to 'not (x and y is z)':HIGH
-improve-conditionals:33:9:33:29:f1:Rewrite conditional expression to 'x and y':HIGH
-improve-conditionals:35:16:35:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH
-improve-conditionals:37:9:37:33:f1:Rewrite conditional expression to 'not (x and y >= 0 and z > 0)':HIGH
-improve-conditionals:39:9:39:33:f1:Rewrite conditional expression to 'not (x and y <= 0 and z < 0)':HIGH

From 0f72f23d12559dc00a08acbec41c2ebcf484d0c0 Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Mon, 13 Oct 2025 13:51:14 +0200
Subject: [PATCH 8/8] Update message

---
 doc/user_guide/checkers/extensions.rst             |  2 +-
 pylint/extensions/code_style.py                    |  2 +-
 .../cs_consider_rewriting_conditional.txt          | 14 +++++++-------
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/doc/user_guide/checkers/extensions.rst b/doc/user_guide/checkers/extensions.rst
index 14e5ae0107..07d3588a29 100644
--- a/doc/user_guide/checkers/extensions.rst
+++ b/doc/user_guide/checkers/extensions.rst
@@ -92,7 +92,7 @@ Code Style checker Messages
   Using math.inf or math.nan permits to benefit from typing and it is up to 4
   times faster than a float call (after the initial import of math). This check
   also catches typos in float calls as a side effect.
-:consider-rewriting-conditional (R6107): *Rewrite conditional expression to '%s'*
+:consider-rewriting-conditional (R6107): *Consider rewriting conditional expression to '%s'*
   Rewrite negated if expressions to improve readability. This style is simpler
   and also permits converting long if/elif chains to match case with more ease.
   Disabled by default!
diff --git a/pylint/extensions/code_style.py b/pylint/extensions/code_style.py
index e17c9358c0..0005084c63 100644
--- a/pylint/extensions/code_style.py
+++ b/pylint/extensions/code_style.py
@@ -91,7 +91,7 @@ class CodeStyleChecker(BaseChecker):
             "This check also catches typos in float calls as a side effect.",
         ),
         "R6107": (
-            "Rewrite conditional expression to '%s'",
+            "Consider rewriting conditional expression to '%s'",
             "consider-rewriting-conditional",
             "Rewrite negated if expressions to improve readability. This style is simpler "
             "and also permits converting long if/elif chains to match case with more ease.\n"
diff --git a/tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt
index 2ada42ac0d..fb1c1e026c 100644
--- a/tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt
+++ b/tests/functional/ext/code_style/cs_consider_rewriting_conditional.txt
@@ -1,7 +1,7 @@
-consider-rewriting-conditional:28:7:28:68:f1:Rewrite conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
-consider-rewriting-conditional:30:9:30:28:f1:Rewrite conditional expression to 'not (x and y in z)':HIGH
-consider-rewriting-conditional:32:9:32:28:f1:Rewrite conditional expression to 'not (x and y is z)':HIGH
-consider-rewriting-conditional:34:9:34:29:f1:Rewrite conditional expression to 'x and y':HIGH
-consider-rewriting-conditional:36:16:36:30:f1:Rewrite conditional expression to 'not (y and z)':HIGH
-consider-rewriting-conditional:38:9:38:33:f1:Rewrite conditional expression to 'not (x and y >= 0 and z > 0)':HIGH
-consider-rewriting-conditional:40:9:40:33:f1:Rewrite conditional expression to 'not (x and y <= 0 and z < 0)':HIGH
+consider-rewriting-conditional:28:7:28:68:f1:Consider rewriting conditional expression to 'not (isinstance(expr, node_cls) and expr.attrname == '__init__')':HIGH
+consider-rewriting-conditional:30:9:30:28:f1:Consider rewriting conditional expression to 'not (x and y in z)':HIGH
+consider-rewriting-conditional:32:9:32:28:f1:Consider rewriting conditional expression to 'not (x and y is z)':HIGH
+consider-rewriting-conditional:34:9:34:29:f1:Consider rewriting conditional expression to 'x and y':HIGH
+consider-rewriting-conditional:36:16:36:30:f1:Consider rewriting conditional expression to 'not (y and z)':HIGH
+consider-rewriting-conditional:38:9:38:33:f1:Consider rewriting conditional expression to 'not (x and y >= 0 and z > 0)':HIGH
+consider-rewriting-conditional:40:9:40:33:f1:Consider rewriting conditional expression to 'not (x and y <= 0 and z < 0)':HIGH