From feca907976aea32abc9910c1b6800ff58dd65cc4 Mon Sep 17 00:00:00 2001
From: Tim Martin <tim@asymptotic.co.uk>
Date: Wed, 27 Apr 2022 19:37:41 +0100
Subject: [PATCH] Avoid reporting superfluous-parens after an ``is not``
 operator (#6451)

---
 ChangeLog                                |  4 ++++
 doc/whatsnew/2.13.rst                    |  4 ++++
 pylint/checkers/format.py                | 10 +++++++++-
 tests/functional/s/superfluous_parens.py |  7 +++++++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index ee6e4b3f95..6fcce762ea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -25,6 +25,10 @@ Release date: TBA
 
   Closes #6414
 
+* Avoid reporting ``superfluous-parens`` on expressions using the ``is not`` operator.
+
+  Closes #5930
+
 
 What's New in Pylint 2.13.7?
 ============================
diff --git a/doc/whatsnew/2.13.rst b/doc/whatsnew/2.13.rst
index bd002d0216..c28b94023a 100644
--- a/doc/whatsnew/2.13.rst
+++ b/doc/whatsnew/2.13.rst
@@ -611,6 +611,10 @@ Other Changes
 
   Closes #5931
 
+* Avoid reporting ``superfluous-parens`` on expressions using the ``is not`` operator.
+
+  Closes #5930
+
 * Fix a crash when linting a file that passes an integer ``mode=`` to
   ``open``
 
diff --git a/pylint/checkers/format.py b/pylint/checkers/format.py
index 70c56a621a..4bf174df2d 100644
--- a/pylint/checkers/format.py
+++ b/pylint/checkers/format.py
@@ -339,6 +339,14 @@ def _check_keyword_parentheses(
             self._bracket_stack.pop()
         if tokens[start + 1].string != "(":
             return
+        if (
+            tokens[start].string == "not"
+            and start > 0
+            and tokens[start - 1].string == "is"
+        ):
+            # If this is part of an `is not` expression, we have a binary operator
+            # so the parentheses are not necessarily redundant.
+            return
         found_and_or = False
         contains_walrus_operator = False
         walrus_operator_depth = 0
@@ -412,7 +420,7 @@ def _check_keyword_parentheses(
                 elif token[1] == "for":
                     return
                 # A generator expression can have an 'else' token in it.
-                # We check the rest of the tokens to see if any problems incur after
+                # We check the rest of the tokens to see if any problems occur after
                 # the 'else'.
                 elif token[1] == "else":
                     if "(" in (i.string for i in tokens[i:]):
diff --git a/tests/functional/s/superfluous_parens.py b/tests/functional/s/superfluous_parens.py
index ee835f6d08..5c91c99ee0 100644
--- a/tests/functional/s/superfluous_parens.py
+++ b/tests/functional/s/superfluous_parens.py
@@ -68,3 +68,10 @@ class ClassA:
 
     def __iter__(self):
         return ((k, getattr(self, k)) for k in self.keys)
+
+if (A == 2) is not (B == 2):
+    pass
+
+M = A is not (A <= H)
+M = True is not (M == K)
+M = True is not (True is not False)