From 2ceef645596d53ea5c4b6d14114e726f1829d912 Mon Sep 17 00:00:00 2001
From: Kadir Can Ozden <101993364+bysiber@users.noreply.github.com>
Date: Fri, 20 Feb 2026 16:42:08 +0300
Subject: [PATCH 1/3] Fix incorrect self-comparison for InfinityType and
 NegativeInfinityType

InfinityType.__le__ unconditionally returns False and __gt__
unconditionally returns True, which gives wrong results for
self-comparison: Infinity <= Infinity returns False (should be
True) and Infinity > Infinity returns True (should be False).

The same issue exists for NegativeInfinityType where __lt__ always
returns True and __ge__ always returns False, making
NegativeInfinity < NegativeInfinity return True and
NegativeInfinity >= NegativeInfinity return False.

Fix by checking isinstance for these four operators, consistent
with how __eq__ is already implemented.
---
 src/packaging/_structures.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/packaging/_structures.py b/src/packaging/_structures.py
index 225e2eee0..74b759807 100644
--- a/src/packaging/_structures.py
+++ b/src/packaging/_structures.py
@@ -19,13 +19,13 @@ def __lt__(self, other: object) -> bool:
         return False
 
     def __le__(self, other: object) -> bool:
-        return False
+        return isinstance(other, self.__class__)
 
     def __eq__(self, other: object) -> bool:
         return isinstance(other, self.__class__)
 
     def __gt__(self, other: object) -> bool:
-        return True
+        return not isinstance(other, self.__class__)
 
     def __ge__(self, other: object) -> bool:
         return True
@@ -48,7 +48,7 @@ def __hash__(self) -> int:
         return hash(repr(self))
 
     def __lt__(self, other: object) -> bool:
-        return True
+        return not isinstance(other, self.__class__)
 
     def __le__(self, other: object) -> bool:
         return True
@@ -60,7 +60,7 @@ def __gt__(self, other: object) -> bool:
         return False
 
     def __ge__(self, other: object) -> bool:
-        return False
+        return isinstance(other, self.__class__)
 
     def __neg__(self: object) -> InfinityType:
         return Infinity

From 0b2c301530d1a0cffa4674c357c46696b238c096 Mon Sep 17 00:00:00 2001
From: Kadir Can Ozden <101993364+bysiber@users.noreply.github.com>
Date: Fri, 20 Feb 2026 18:15:59 +0300
Subject: [PATCH 2/3] Add self-comparison tests for Infinity types

---
 tests/test_structures.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tests/test_structures.py b/tests/test_structures.py
index d85c96215..6b67d1897 100644
--- a/tests/test_structures.py
+++ b/tests/test_structures.py
@@ -49,10 +49,24 @@ def test_infinity_equal() -> None:
     assert Infinity == Infinity
 
 
+def test_infinity_self_comparison() -> None:
+    assert not Infinity < Infinity
+    assert Infinity <= Infinity
+    assert not Infinity > Infinity
+    assert Infinity >= Infinity
+
+
 def test_negative_infinity_equal() -> None:
     assert NegativeInfinity == NegativeInfinity
 
 
+def test_negative_infinity_self_comparison() -> None:
+    assert not NegativeInfinity < NegativeInfinity
+    assert NegativeInfinity <= NegativeInfinity
+    assert not NegativeInfinity > NegativeInfinity
+    assert NegativeInfinity >= NegativeInfinity
+
+
 def test_negate_infinity() -> None:
     assert isinstance(-Infinity, NegativeInfinity.__class__)
 

From b090b040d3b620a502709dc4bbad8772f21b7e54 Mon Sep 17 00:00:00 2001
From: Kadir Can Ozden <101993364+bysiber@users.noreply.github.com>
Date: Sat, 21 Feb 2026 21:40:09 +0300
Subject: [PATCH 3/3] Use identity checks instead of isinstance for singleton
 comparison

Since Infinity and NegativeInfinity are singletons, 'other is self'
is both cheaper and more correct than isinstance checks.
---
 src/packaging/_structures.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/packaging/_structures.py b/src/packaging/_structures.py
index 74b759807..74ca8f0c0 100644
--- a/src/packaging/_structures.py
+++ b/src/packaging/_structures.py
@@ -19,13 +19,13 @@ def __lt__(self, other: object) -> bool:
         return False
 
     def __le__(self, other: object) -> bool:
-        return isinstance(other, self.__class__)
+        return other is self
 
     def __eq__(self, other: object) -> bool:
-        return isinstance(other, self.__class__)
+        return other is self
 
     def __gt__(self, other: object) -> bool:
-        return not isinstance(other, self.__class__)
+        return other is not self
 
     def __ge__(self, other: object) -> bool:
         return True
@@ -48,19 +48,19 @@ def __hash__(self) -> int:
         return hash(repr(self))
 
     def __lt__(self, other: object) -> bool:
-        return not isinstance(other, self.__class__)
+        return other is not self
 
     def __le__(self, other: object) -> bool:
         return True
 
     def __eq__(self, other: object) -> bool:
-        return isinstance(other, self.__class__)
+        return other is self
 
     def __gt__(self, other: object) -> bool:
         return False
 
     def __ge__(self, other: object) -> bool:
-        return isinstance(other, self.__class__)
+        return other is self
 
     def __neg__(self: object) -> InfinityType:
         return Infinity