Avoid reporting superfluous-parens after an is not operator (#6451)

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?
 ============================

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``
 

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:]):

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)